Outcomes of Subtotal Colectomy with Ileorectal Anastomosis and Regular Colonoscopic Surveillance of Polypectomy in Patients with Familial Adenomatous Polyposis

Outcomes of Subtotal Colectomy with Ileorectal Anastomosis and Regular Colonoscopic Surveillance of Polypectomy in Patients with Familial Adenomatous Polyposis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Outcomes of Subtotal Colectomy with Ileorectal Anastomosis and Regular Colonoscopic Surveillance of Polypectomy in Patients with Familial Adenomatous Polyposis Chi-Han YANG, Hsiang-Lin TSAI, Yen-Cheng CHEN, Po-Jung CHEN, Tsung-Kun CHANG, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7934102/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Familial adenomatous polyposis (FAP) is an inherited disorder caused by mutations in the adenomatous polyposis coli gene, causing numerous colorectal adenomas to develop. If left untreated, FAP is associated with a nearly 100% lifetime risk of colorectal cancer. Subtotal colectomy with ileorectal anastomosis (IRA) is a surgical option that preserves rectal function but necessitates intensive postoperative surveillance due to the residual risk of malignancy in the retained rectum. Methods This retrospective study included seven patients with FAP who underwent subtotal colectomy with IRA at a single institution between 2015 and 2024. Postoperative management involved intensive colonoscopic surveillance and polypectomy of rectal lesions. Clinical and pathological data were analyzed, including the incidence of residual rectal polyps, bowel function, and clinical outcomes. Results All patients developed residual rectal polyps during follow-up, which were successfully removed through polypectomy without evidence of malignant transformation. Bowel function was well-preserved in all patients, with rectal lengths ranging from 10 to 15 cm. Silymarin, a natural polyphenolic flavonoid with potential chemopreventive effects, was administered to six of the seven patients, among whom it was well-tolerated. The long-term effects of silymarin are under evaluation during ongoing follow-up. Conclusion Subtotal colectomy with IRA, combined with regular colonoscopic surveillance and timely polypectomy, can effectively manage FAP and preserve bowel function. Silymarin may be a promising adjunctive chemopreventive agent; however, further clinical trials are needed to validate its efficacy and safety in human populations. These findings highlight the necessity of individualized surgical planning and vigilant long-term surveillance in FAP management. colonoscopic surveillance familial adenomatous polyposis ileorectal anastomosis Background Familial adenomatous polyposis (FAP) is an inherited disorder caused by pathogenic mutations in the adenomatous polyposis coli ( APC ) gene, which disrupts regulation of the Wnt/β-catenin signaling pathway and drives the formation of colorectal adenomas. Affected individuals typically develop hundreds to thousands of adenomas during adolescence, which are associated with a nearly 100% lifetime risk of colorectal cancer (CRC) if left untreated. In addition to colorectal polyps, FAP is associated with extracolonic manifestations, including duodenal adenomas, desmoid tumors, and malignancies in other organs, such as the stomach and thyroid ( 1 ). FAP management typically involves either ileorectal anastomosis (IRA) or ileal pouch-anal anastomosis (IPAA). IRA preserves rectal function, is associated with fewer postoperative complications, and generally results in better quality of life than IPAA. However, IRA requires lifelong endoscopic surveillance due to the continued risk of rectal cancer from residual mucosa. By contrast, IPAA is a more complex procedure that eliminates the risk of CRC through the removal of all colorectal mucosa that is associated with higher rates of bowel dysfunction and other complications, potentially affecting long-term functional outcomes ( 2 ). The British Society of Gastroenterology recommends total colectomy with IRA for patients with relative rectal sparing, defined as fewer than 20 rectal polyps, particularly when adenomas are less than 5 mm in diameter or when larger polyps are amenable to endoscopic resection. These guidelines emphasize that surgical decision-making should account for the rectal polyp burden, associated cancer risk, and the patient’s ability and willingness to adhere to long-term endoscopic surveillance ( 3 ). In this study, we reviewed seven patients with FAP who received IRA at a single institution, focusing on clinical outcomes and challenges during postoperative colonoscopy surveillance. The study findings highlight the effectiveness of IRA in selected cases and its role in FAP management. Materials and methods Case presentation Between 2015 and 2024, seven patients diagnosed with FAP or related polyposis syndromes were treated at our institution (Table 1). The cohort included four males and three females, with a median age of 24 years (range: 20–63 years) at the time of diagnosis. Patients 1, 2, and 7 had a documented family history of FAP and CRC. Patients 3, 4, and 5 were siblings with a familial history of FAP and colorectal malignancy. In all patients, colonoscopy revealed more than 100 colorectal polyps of varying number and histopathological characteristics. Most patients presented with diarrhea, anemia, abdominal pain, or hematochezia; however, one case was identified incidentally during routine screening. Histopathological analysis predominantly revealed tubular adenomas, with tubulovillous adenomas or adenocarcinoma observed in several patients. Surgical management typically involved resection up to the rectosigmoid junction; however, in cases with substantial rectal involvement, resection was extended to include the upper rectum. This retrospective review highlights the heterogeneous clinical and colonoscopic features of FAP, underscoring the need for individualized surgical strategies based on the extent of rectal disease. Three of the seven patients underwent genetic testing for APC mutations based on clinical indications and informed consent. Germline testing was performed for all three individuals using a targeted multi-gene panel provided by Invitae (San Francisco, CA, USA). Genomic DNA was extracted from peripheral blood samples, enriched for target regions through a hybridization-based protocol, and sequenced on an Illumina platform. Sequence reads were aligned to the GRCh37 human genome reference, and variant analysis was conducted with respect to clinically relevant transcripts. The assay detected single nucleotide variants, small insertions and deletions, and exon-level deletions and duplications, with a minimum sequencing depth of 50× across all targeted regions. Distinct APC mutations were identified in all three patients tested, including a point mutation in exon 15 (c.5465T > A) in Patient 1, a deletion mutation in exon 16 (c.3183_3187del) in Patient 3, and a promoter region variant (c.-30266G > A) in Patient 6. This study involving human participants was reviewed and approved by the institutional review board of Kaohsiung Medical University Hospital, Taiwan (approval no. KMUHIRB E(I)-20230267), which waived the requirement for informed consent. Surgical intervention and postoperative follow-up All seven patients underwent subtotal colectomy with ileorectal side-to-end anastomosis and subsequently completed intensive colonoscopic surveillance during follow-up. The surveillance strategy recommended under the 2024 clinical guidelines issued by the European Society of Coloproctology and the American Society of Colon and Rectal Surgeons (ASCRS) involves endoscopic monitoring every 6–12 months following IRA. In our clinical practice, we adopted a more rigorous protocol and conducted colonoscopies every 3–6 months during the initial 2 years postoperatively. Thereafter, colonoscopies were conducted every 6–12 months depending on the number, size, and histopathological features of previously identified adenomas. Postoperative colonoscopic evaluation enabled us to document the length of the remaining rectum and colon and perform biopsies and histopathological examinations when rectal polyps were identified. During outpatient visits, daily bowel movement frequency was recorded, and patients were monitored for any postoperative complications. All patients adhered to the surveillance protocol during the initial postoperative period. Patient 2 was lost to follow-up 5 years after surgery, and the remaining 6 patients continued to receive active surveillance at our institution. No statistical analyses were performed in this study, as it is a descriptive retrospective case series involving a small number of patients. Table I Clinical and Pathological Characteristics of Seven Patients with Familial adenomatous polyposis Case Sex Age of diagnosis Date of diagnosis Initial clinical manifestations Colonoscopy finding Biopsy pathology 1 M 22 August 2015 Frequent diarrhea Multiple colon polyp over entire colon till rectum Tubular adenoma 2 M 46 March 2017 Chronic anemia Multiple polyps lesion over entire colon till rectum; one malignant lesion in sigmoid colon Tubular adenoma; adenocarcinoma 3 F 26 February 2022 Asymptotic Multiple polyps over entire colon till rectum Tubular adenoma 4 F 23 March 2023 Asymptotic Multiple polyps from transverse colon to rectum Tubular adenoma 5 M 20 February 2023 Abdominal pain and bloody stool Multiple polyps over entire colon to rectum Tubular adenoma 6 M 63 March 2023 Abdominal pain and bloody stool Multiple colon polyp over entire colon; one malignant lesion in ascending colon Tubular adenoma; adenocarcinoma 7 F 24 July 2024 Abdominal pain and vomiting Multiple colon polyp over entire colon till rectum Tubulovillous adenoma Table I Clinical and Pathological Characteristics of Seven Patients with Familial adenomatous polyposis (Continued) Operation date Operation method Pathologic report Remained rectum length (cm) Total times of polypectomy during colonoscopy Postoperative colonoscopy pathology report Follow-up duration (month) October 2020 Subtotal colectomy with ileorectal anastomosis Tubular adenoma 10 7 Tubular adenoma, low grade dysplasia 52.1 April 2017 Subtotal colectomy with ileorectal anastomosis Sigmoid colon adenocarcinoma, pT2N0M0, stage 1 15 2 Tubular adenoma, low grade dysplasia 60.0 April 2022 Subtotal colectomy with ileorectal anastomosis Tubular adenoma 15 5 Tubular adenoma, low grade dysplasia 30.3 April 2023 Subtotal colectomy with ileorectal anastomosis Tubular adenoma 15 3 Tubular adenoma, low grade dysplasia 22.7 February 2023 Subtotal colectomy with ileorectal anastomosis Tubular adenoma 10 4 Tubular adenoma, low grade dysplasia 18.0 March 2023 Subtotal colectomy with ileorectal anastomosis Ascending colon adenocarcinoma, pT3N0M0, stage IIA 15 0 Unremarkable 23.2 November 2024 Subtotal colectomy with ileorectal anastomosis Tubular adenoma 10 1 Tubular adenoma, low grade dysplasia 5.0 Results During the first 2 years following surgery, follow-up colonoscopies were scheduled approximately every 3–6 months for each patient. Subsequent surveillance intervals were individualized based on the number and characteristics of polyps detected during prior examinations, with most patients undergoing colonoscopy every 6 months. Polypectomy was performed whenever rectal polyps were identified. Six of the seven patients developed residual rectal polyps postoperatively and underwent endoscopic polypectomy. Histopathological analysis confirmed low-grade dysplasia in all resected polyps. The median follow-up duration for the cohort was 23.2 months (range: 5–60 months). To date, no malignant adenomas or cancerous lesions have been detected in the residual rectum of any patient. The average length of the remaining rectum in the seven patients ranged from approximately 10–15 cm. During postoperative outpatient follow-up, patients reported an average of 3–5 bowel movements per day, with no episodes of fecal or flatus incontinence observed. We identified several FAP-associated tumors in our patients, highlighting the extracolonic manifestations of this disease. Patient 2 developed multifocal papillary thyroid microcarcinomas in 2021, 4 years after the initial FAP diagnosis, and subsequently underwent total thyroidectomy followed by radioiodine ablation therapy. Patient 3 was diagnosed with papillary thyroid carcinoma in 2021, 1 year before FAP diagnosis, and was treated with left total and right subtotal thyroidectomy in December 2021. In Patient 7, a mucinous cystadenoma of the pancreatic tail and a fundic gland polyp in the stomach were identified several months before FAP diagnosis; this patient underwent distal pancreatectomy and partial gastrectomy in July 2024. These cases underscore the necessity of comprehensive and multidisciplinary surveillance in patients with FAP, because this condition increases the risk of a broad spectrum of extracolonic neoplasms that require timely detection and management. The seven participating patients completed postoperative follow-up between April 2017 and March 2025. At the final follow-up appointment, no case of rectal cancer had been detected. All patients except for Patient 2 received silymarin as a chemopreventive agent. Although most evidence supporting the role of silymarin in preventing CRC and polyp formation has been derived from preclinical animal studies, its favorable safety profile supports its use in this cohort. Patients underwent long-term monitoring to evaluate the potential effects of silymarin on clinical outcomes. In ongoing outpatient follow-up, rectal polyp status, colonoscopic polypectomy (when indicated), and bowel movement patterns continue to be assessed. Discussion The seven patients with FAP underwent subtotal colectomy with side-to-end IRA, preserving approximately 10–15 cm of rectum. During postoperative follow-up, rectal polyps were detected in six of the seven patients. Intensive surveillance colonoscopies and timely polypectomies prevented progression to rectal cancer in all six of these patients as of March 2025. These findings suggest that when combined with diligent endoscopic surveillance, subtotal colectomy with IRA is a viable treatment option for patients with FAP and no rectal malignancy at the time of surgery. Surveillance protocols were informed by the 2024 guidelines from the European Society of Coloproctology and the ASCRS, which recommend endoscopic follow-up every 6–12 months after IRA; however, we employed a more intensive schedule consisting of colonoscopies every 3–6 months during the first 2 postoperative years, followed by colonoscopies every 6–12-months based on individualized adenoma burden and histopathological findings ( 1 ) ( 4 ). Further studies involving larger patient cohorts and longer follow-up periods are necessary to strengthen the available evidence. Among studies in the literature, Tajika et al . analyzed 84 patients with FAP who underwent surgical treatment between 1965 and 2019, including 22 treated with IPAA and 12 with IRA. Adenoma development was observed in 94.1% of patients; however, no instances of adenocarcinoma were reported, and no additional surgeries were required during the follow-up period ( 5 ). Both the IPAA and IRA groups underwent intensive annual and 6-month endoscopic surveillance, respectively, during the follow-up. The findings of this previous retrospective study highlight that adenomas can develop following both IRA and IPAA. As such, postoperative endoscopic surveillance is essential for all patients, and those undergoing IRA require more frequent monitoring due to the retained rectal mucosa. Both the Clinical Practice Guidelines of the ASCRS and findings from a recent systematic review indicate that colonoscopy should be performed every 6–12 months for patients who have received IRA ( 4 ). A meta-analysis demonstrated that IRA results in superior bowel function compared with IPAA. Patients who underwent IRA reported fewer daily bowel movements, lower rates of nighttime defecation, and a lower incidence of fecal incontinence than those who underwent IPAA. Moreover, IRA was associated with fewer social restrictions (4% vs. 14%) and comparable rates of sexual dysfunction and dietary limitations to IPAA. These functional advantages make IRA a compelling surgical option for patients with FAP and a limited rectal polyp burden, particularly those who prioritize the preservation of bowel function and quality of life ( 6 ). Maehata et al . retrospectively analyzed 27 patients with FAP who underwent IRA between 1990 and 2004. During the follow-up period, 10 patients developed rectal cancer (37.0%), indicating a substantial risk of cancer in the rectal remnant (CRR) following IRA ( 7 ). The cumulative incidence of CRR following IRA has been reported as 8%, 19%, and 57% at 10, 20, and 30 years, respectively. Although IRA is technically less complex than IPAA, it is associated with a significantly higher long-term risk of CRR, particularly without rigorous postoperative surveillance. Therefore, individualized, long-term monitoring is critical to ensure early detection and timely management of CRR, especially in high-risk patients, given that the risk of malignant transformation increases substantially over time. In a separate retrospective analysis of 37 patients with FAP, Sasaki et al . reported that although IRA was associated with a higher incidence of rectal cancer compared with IPAA, it offered superior preservation of anal function, supporting its use in carefully selected patients with a limited rectal polyp burden to maintain bowel function and quality of life ( 8 ). Nevertheless, the risk of metachronous rectal cancer increases over time, underscoring the need for intensive endoscopic surveillance ( 9 ). Previous animal studies have demonstrated that silymarin, a polyphenolic flavonoid derived from milk thistle (Silybum marianum), possesses promising chemopreventive properties against CRC ( 10 ). In azoxymethane-treated rats, silymarin reduced aberrant crypt foci and colonic adenocarcinomas by increasing detoxifying enzymes and lowering β-glucuronidase and prostaglandin E2 levels. In APC min/+ mice, silymarin inhibited microbial β-glucuronidase, preventing dysbiosis and tumor formation ( 11 ). These findings suggest that silymarin can modulate gut microbiota and tumorigenic pathways, warranting further clinical research. Therefore, in addition to close colonoscopic surveillance, we administered silymarin as a chemopreventive agent to all patients except Patient 2. Although current evidence supporting the use of silymarin to prevent CRC and polyps is primarily derived from animal models, its favorable safety profile prompted us to administer silymarin under close monitoring of patients’ long-term clinical outcomes. We anticipate that future studies with more robust clinical data can contribute to validating the efficacy of silymarin in this context; the current lack of such data remains a major limitation. Prospective, multicenter randomized controlled trials are needed to evaluate the efficacy, optimal dosing, safety, and long-term outcomes of silymarin in patients at high risk of CRC and polyps. Biomarker-guided approaches may elucidate the role of silymarin in precision chemoprevention strategies. The small sample size, single-center design, and relatively short follow-up period of our study precluded comprehensive long-term risk assessment and may limit the generalizability of our findings. Additionally, only three of the seven patients included consented to genetic testing. Given that patients with FAP—particularly those under 30 years of age—require lifelong surveillance to monitor disease progression and prevent malignant transformation, the limited follow-up duration in this study further restricted the evaluation of long-term outcomes. To improve FAP management and surveillance strategies, future studies should include larger, multicenter cohorts, expansive genetic analyses, and direct comparisons between IRA and IPAA. Conclusion This study demonstrated that subtotal colectomy with IRA, when combined with intensive endoscopic surveillance, can effectively manage FAP by preserving rectal function and enabling timely detection and treatment of adenomas. Given the higher long-term risk of rectal cancer associated with IRA compared with IPAA, sustained surveillance remains essential. Further multicenter studies and direct comparative analyses between IRA and IPAA are warranted to optimize surgical decision-making and long-term management strategies for patients with FAP. Abbreviations FAP Familial Adenomatous Polyposis IRA Ileorectal Anastomosis IPAA Ileal Pouch-Anal Anastomosis CRR Cancer in the Rectal Remnant AAV Anorectal Anal Verge APC Adenomatous Polyposis Coli Declarations Ethics Approval and Consent to Participate The study was approved by the Institutional Review Board of Kaohsiung Medical University Hospital (approval no. KMUHIRB-E(I)-20230267), which waived the requirement for obtaining written informed consent due to the retrospective design of the study. Consent for Publication The requirement for written informed consent for publication was waived by the Institutional Review Board of Kaohsiung Medical University Hospital due to the retrospective nature of the study. No identifiable patient data are presented in this manuscript. Competing Interest The authors declare that they have no competing interest with regard to the content of this article. Funding The authors received no specific funding for this study. Author Contribution The authors confirm contribution to the paper as follows: study conception and design: Jaw-Yuan Wang, Hsiang-Lin Tsai; data collection: Ching-Wen Huang, Wei-Chih Su, Tsung-Kun Chang; analysis and interpretation of results: Po-Jung Chen, Yen-Cheng Chen ; draft manuscript preparation: Chi-Han Yang. All authors reviewed the results and approved the final version of the manuscript. Acknowledgement This work was supported by grants through funding from the National Science and Technology Council (MOST 111-2314-B-037-070-MY3, NSTC 112-2314-B-037-050-MY3, NSTC 113-2321-B-037-006, NSTC 113-2314-B-037-057, NSTC 114-2314-B-037-103-MY3, NSTC 114-2321-B-037-003) and the Ministry of Health and Welfare (MOHW113-TDU-B-222-134014) and funded by the health and welfare surcharge of on tobacco products, and the Kaohsiung Medical University Hospital (KMUH112-2R37, KMUH112-2R38, KMUH112-2R39, KMUH112-2M27, KMUH112-2M28, KMUH112-2M29, KMUH113-2R31, KMUH113-2R32, KMUH113-2R33, KMUH113-3M58, KMUH113-3M59, KMUH-S11303, KMUH-SH11309, KMUH-SI11327), Kaohsiung Medical University Research Center Grant (KMU-TC113A04) and National Tsing Hua University-Kaohsiung Medical University Joint Research Project (NTHU-KMU-KT114P008). In addition, this study was supported by the Grant of Taiwan Precision Medicine Initiative and Taiwan Biobank, Academia Sinica, Taiwan, R.O.C. Data Availability The Illumina sequencing was performed by a commercial genetic testing company (Invitae). The identified variants have been submitted to ClinVar, a publicly available database. The ClinVar entries for the relevant patients are as follows:Patient 3: [https://www.ncbi.nlm.nih.gov/clinvar/variation/88913/](https:/www.ncbi.nlm.nih.gov/clinvar/variation/88913)Patient6: [https://www.ncbi.nlm.nih.gov/clinvar/variation/1002757/?oq=NM\_000038.5:c.-30266G%3EA&m=NM\_001127511.3(APC):c.-40G%3EA](https:/www.ncbi.nlm.nih.gov/clinvar/variation/1002757/?oq=NM_000038.5:c.-30266G%3EA&m=NM_001127511.3(APC):c.-40G%3EA)The raw sequencing data are not publicly available due to restrictions associated with the use of a third-party clinical testing service. 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Cheng KW, Tseng CH, Chen IJ, Huang BC, Liu HJ, Ho KW, Lin WW, Chuang CH, Huang MY, et al. : Inhibition of gut microbial β-glucuronidase effectively prevents carcinogen-induced microbial dysbiosis and intestinal tumorigenesis. Pharmacological Research 177: 106115, 2022. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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WANG","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIie3QMUvEMBQH8HcEziVSxyfKLX6BBwWtk1+lR4dbqtyY4dCbdBFuLdyXEPwCrwS8pbMUTvCkcHM/QBFf6uSQ6uiQ/5A8kvx4SQBCQv5lFDMSTiIpGYH1H8h4ysk8iY+XMOKkJ8ot0wDRZ2xaM31i6WeA4VcSFTlwTTh6ft3suIa304uDFau56bwE62suC0J1vs2pLGCvLx8tqKLydyG8Sa08fywELILVVGegDu+HSE62I9TxeraznSPvjZDPYeI+GekklaLvooQs/QSrfeoI4ba3QqpMxpfYS6KHzLbY3d6t1rOmRWOvaFN+NHox8RI4Sn/c83ti/3nXZng7JCQkJATgCybTWVN3U7QpAAAAAElFTkSuQmCC","orcid":"","institution":"Kaohsiung Medical University Hospital, Kaohsiung Medical University","correspondingAuthor":true,"prefix":"","firstName":"Jaw-Yuan","middleName":"","lastName":"WANG","suffix":""}],"badges":[],"createdAt":"2025-10-23 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10:54:15","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":15326,"visible":true,"origin":"","legend":"","description":"","filename":"Table1Ver.1.docx","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/1b36551b56fc7ce0a0ed55b1.docx"},{"id":96815367,"identity":"65c6793e-02b3-477e-8fb9-b7013ec4eff3","added_by":"auto","created_at":"2025-11-26 10:54:16","extension":"json","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":11089,"visible":true,"origin":"","legend":"","description":"","filename":"bef9f25d0db648e4b89fc8ed32c9dc6b.json","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/82983ebeb06c74798a6cb53e.json"},{"id":96815376,"identity":"5cc31ca0-74e0-4fdf-abcc-349e6c4d910b","added_by":"auto","created_at":"2025-11-26 10:54:18","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":78741,"visible":true,"origin":"","legend":"","description":"","filename":"bef9f25d0db648e4b89fc8ed32c9dc6b1enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/5fd225e4a76bdbc19dea5729.xml"},{"id":96815377,"identity":"0abc0eea-f965-41ba-942d-3758607b9167","added_by":"auto","created_at":"2025-11-26 10:54:18","extension":"xml","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":76795,"visible":true,"origin":"","legend":"","description":"","filename":"bef9f25d0db648e4b89fc8ed32c9dc6b1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/834dc4b6b2ea34dae44a4088.xml"},{"id":96815379,"identity":"33501751-c6e3-4b53-b5dd-fc1c23774c9c","added_by":"auto","created_at":"2025-11-26 10:54:18","extension":"html","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":84791,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/9103d70ebd4ff77f8634bb99.html"},{"id":105035815,"identity":"6efaebc8-101a-4b78-8b4e-559df4183372","added_by":"auto","created_at":"2026-03-20 07:26:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":648613,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7934102/v1/de091ce3-c823-4012-a5da-d60b79311f23.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Outcomes of Subtotal Colectomy with Ileorectal Anastomosis and Regular Colonoscopic Surveillance of Polypectomy in Patients with Familial Adenomatous Polyposis","fulltext":[{"header":"Background","content":"\u003cp\u003eFamilial adenomatous polyposis (FAP) is an inherited disorder caused by pathogenic mutations in the adenomatous polyposis coli (\u003cem\u003eAPC\u003c/em\u003e) gene, which disrupts regulation of the Wnt/β-catenin signaling pathway and drives the formation of colorectal adenomas. Affected individuals typically develop hundreds to thousands of adenomas during adolescence, which are associated with a nearly 100% lifetime risk of colorectal cancer (CRC) if left untreated. In addition to colorectal polyps, FAP is associated with extracolonic manifestations, including duodenal adenomas, desmoid tumors, and malignancies in other organs, such as the stomach and thyroid (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFAP management typically involves either ileorectal anastomosis (IRA) or ileal pouch-anal anastomosis (IPAA). IRA preserves rectal function, is associated with fewer postoperative complications, and generally results in better quality of life than IPAA. However, IRA requires lifelong endoscopic surveillance due to the continued risk of rectal cancer from residual mucosa. By contrast, IPAA is a more complex procedure that eliminates the risk of CRC through the removal of all colorectal mucosa that is associated with higher rates of bowel dysfunction and other complications, potentially affecting long-term functional outcomes (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The British Society of Gastroenterology recommends total colectomy with IRA for patients with relative rectal sparing, defined as fewer than 20 rectal polyps, particularly when adenomas are less than 5 mm in diameter or when larger polyps are amenable to endoscopic resection. These guidelines emphasize that surgical decision-making should account for the rectal polyp burden, associated cancer risk, and the patient\u0026rsquo;s ability and willingness to adhere to long-term endoscopic surveillance (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn this study, we reviewed seven patients with FAP who received IRA at a single institution, focusing on clinical outcomes and challenges during postoperative colonoscopy surveillance. The study findings highlight the effectiveness of IRA in selected cases and its role in FAP management.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eCase presentation\u003c/h2\u003e\u003cp\u003eBetween 2015 and 2024, seven patients diagnosed with FAP or related polyposis syndromes were treated at our institution (Table\u0026nbsp;1). The cohort included four males and three females, with a median age of 24 years (range: 20\u0026ndash;63 years) at the time of diagnosis. Patients 1, 2, and 7 had a documented family history of FAP and CRC. Patients 3, 4, and 5 were siblings with a familial history of FAP and colorectal malignancy. In all patients, colonoscopy revealed more than 100 colorectal polyps of varying number and histopathological characteristics. Most patients presented with diarrhea, anemia, abdominal pain, or hematochezia; however, one case was identified incidentally during routine screening. Histopathological analysis predominantly revealed tubular adenomas, with tubulovillous adenomas or adenocarcinoma observed in several patients. Surgical management typically involved resection up to the rectosigmoid junction; however, in cases with substantial rectal involvement, resection was extended to include the upper rectum. This retrospective review highlights the heterogeneous clinical and colonoscopic features of FAP, underscoring the need for individualized surgical strategies based on the extent of rectal disease.\u003c/p\u003e\u003cp\u003eThree of the seven patients underwent genetic testing for \u003cem\u003eAPC\u003c/em\u003e mutations based on clinical indications and informed consent. Germline testing was performed for all three individuals using a targeted multi-gene panel provided by Invitae (San Francisco, CA, USA). Genomic DNA was extracted from peripheral blood samples, enriched for target regions through a hybridization-based protocol, and sequenced on an Illumina platform. Sequence reads were aligned to the GRCh37 human genome reference, and variant analysis was conducted with respect to clinically relevant transcripts. The assay detected single nucleotide variants, small insertions and deletions, and exon-level deletions and duplications, with a minimum sequencing depth of 50\u0026times; across all targeted regions.\u003c/p\u003e\u003cp\u003eDistinct \u003cem\u003eAPC\u003c/em\u003e mutations were identified in all three patients tested, including a point mutation in exon 15 (c.5465T\u0026thinsp;\u0026gt;\u0026thinsp;A) in Patient 1, a deletion mutation in exon 16 (c.3183_3187del) in Patient 3, and a promoter region variant (c.-30266G\u0026thinsp;\u0026gt;\u0026thinsp;A) in Patient 6.\u003c/p\u003e\u003cp\u003e This study involving human participants was reviewed and approved by the institutional review board of Kaohsiung Medical University Hospital, Taiwan (approval no. KMUHIRB E(I)-20230267), which waived the requirement for informed consent.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSurgical intervention and postoperative follow-up\u003c/h3\u003e\n\u003cp\u003eAll seven patients underwent subtotal colectomy with ileorectal side-to-end anastomosis and subsequently completed intensive colonoscopic surveillance during follow-up. The surveillance strategy recommended under the 2024 clinical guidelines issued by the European Society of Coloproctology and the American Society of Colon and Rectal Surgeons (ASCRS) involves endoscopic monitoring every 6\u0026ndash;12 months following IRA. In our clinical practice, we adopted a more rigorous protocol and conducted colonoscopies every 3\u0026ndash;6 months during the initial 2 years postoperatively. Thereafter, colonoscopies were conducted every 6\u0026ndash;12 months depending on the number, size, and histopathological features of previously identified adenomas.\u003c/p\u003e\u003cp\u003ePostoperative colonoscopic evaluation enabled us to document the length of the remaining rectum and colon and perform biopsies and histopathological examinations when rectal polyps were identified. During outpatient visits, daily bowel movement frequency was recorded, and patients were monitored for any postoperative complications. All patients adhered to the surveillance protocol during the initial postoperative period. Patient 2 was lost to follow-up 5 years after surgery, and the remaining 6 patients continued to receive active surveillance at our institution. No statistical analyses were performed in this study, as it is a descriptive retrospective case series involving a small number of patients.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable I\u003c/strong\u003e\u003cp\u003eClinical and Pathological Characteristics of Seven Patients with Familial adenomatous polyposis\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAge of diagnosis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDate of diagnosis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInitial clinical manifestations\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eColonoscopy finding\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBiopsy pathology\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAugust 2015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eFrequent diarrhea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple colon polyp over entire colon till rectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMarch 2017\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eChronic anemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple polyps lesion over entire colon till rectum; one malignant lesion in sigmoid colon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma; adenocarcinoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFebruary 2022\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAsymptotic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple polyps over entire colon till rectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMarch 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAsymptotic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple polyps from transverse colon to rectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFebruary 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAbdominal pain and bloody stool\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple polyps over entire colon to rectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMarch 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAbdominal pain and bloody stool\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple colon polyp over entire colon; one malignant lesion in ascending colon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubular adenoma; adenocarcinoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eJuly 2024\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAbdominal pain and vomiting\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMultiple colon polyp over entire colon till rectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTubulovillous adenoma\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable I\u003c/strong\u003e\u003cp\u003eClinical and Pathological Characteristics of Seven Patients with Familial adenomatous polyposis (Continued)\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperation date\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOperation method\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePathologic report\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRemained rectum length (cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eTotal times of polypectomy during colonoscopy\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003ePostoperative colonoscopy pathology report\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eFollow-up duration (month)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOctober 2020\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e52.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApril 2017\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSigmoid colon adenocarcinoma, pT2N0M0, stage 1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e60.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApril 2022\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e30.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApril 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e22.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFebruary 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e18.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMarch 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAscending colon adenocarcinoma, pT3N0M0, stage IIA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eUnremarkable\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e23.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNovember 2024\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSubtotal colectomy with ileorectal anastomosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTubular adenoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTubular adenoma, low grade dysplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e5.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eDuring the first 2 years following surgery, follow-up colonoscopies were scheduled approximately every 3\u0026ndash;6 months for each patient. Subsequent surveillance intervals were individualized based on the number and characteristics of polyps detected during prior examinations, with most patients undergoing colonoscopy every 6 months. Polypectomy was performed whenever rectal polyps were identified. Six of the seven patients developed residual rectal polyps postoperatively and underwent endoscopic polypectomy. Histopathological analysis confirmed low-grade dysplasia in all resected polyps. The median follow-up duration for the cohort was 23.2 months (range: 5\u0026ndash;60 months). To date, no malignant adenomas or cancerous lesions have been detected in the residual rectum of any patient.\u003c/p\u003e\u003cp\u003eThe average length of the remaining rectum in the seven patients ranged from approximately 10\u0026ndash;15 cm. During postoperative outpatient follow-up, patients reported an average of 3\u0026ndash;5 bowel movements per day, with no episodes of fecal or flatus incontinence observed.\u003c/p\u003e\u003cp\u003eWe identified several FAP-associated tumors in our patients, highlighting the extracolonic manifestations of this disease. Patient 2 developed multifocal papillary thyroid microcarcinomas in 2021, 4 years after the initial FAP diagnosis, and subsequently underwent total thyroidectomy followed by radioiodine ablation therapy. Patient 3 was diagnosed with papillary thyroid carcinoma in 2021, 1 year before FAP diagnosis, and was treated with left total and right subtotal thyroidectomy in December 2021. In Patient 7, a mucinous cystadenoma of the pancreatic tail and a fundic gland polyp in the stomach were identified several months before FAP diagnosis; this patient underwent distal pancreatectomy and partial gastrectomy in July 2024. These cases underscore the necessity of comprehensive and multidisciplinary surveillance in patients with FAP, because this condition increases the risk of a broad spectrum of extracolonic neoplasms that require timely detection and management.\u003c/p\u003e\u003cp\u003eThe seven participating patients completed postoperative follow-up between April 2017 and March 2025. At the final follow-up appointment, no case of rectal cancer had been detected. All patients except for Patient 2 received silymarin as a chemopreventive agent. Although most evidence supporting the role of silymarin in preventing CRC and polyp formation has been derived from preclinical animal studies, its favorable safety profile supports its use in this cohort. Patients underwent long-term monitoring to evaluate the potential effects of silymarin on clinical outcomes. In ongoing outpatient follow-up, rectal polyp status, colonoscopic polypectomy (when indicated), and bowel movement patterns continue to be assessed.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe seven patients with FAP underwent subtotal colectomy with side-to-end IRA, preserving approximately 10\u0026ndash;15 cm of rectum. During postoperative follow-up, rectal polyps were detected in six of the seven patients. Intensive surveillance colonoscopies and timely polypectomies prevented progression to rectal cancer in all six of these patients as of March 2025. These findings suggest that when combined with diligent endoscopic surveillance, subtotal colectomy with IRA is a viable treatment option for patients with FAP and no rectal malignancy at the time of surgery. Surveillance protocols were informed by the 2024 guidelines from the European Society of Coloproctology and the ASCRS, which recommend endoscopic follow-up every 6\u0026ndash;12 months after IRA; however, we employed a more intensive schedule consisting of colonoscopies every 3\u0026ndash;6 months during the first 2 postoperative years, followed by colonoscopies every 6\u0026ndash;12-months based on individualized adenoma burden and histopathological findings (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Further studies involving larger patient cohorts and longer follow-up periods are necessary to strengthen the available evidence.\u003c/p\u003e\u003cp\u003eAmong studies in the literature, Tajika \u003cem\u003eet al\u003c/em\u003e. analyzed 84 patients with FAP who underwent surgical treatment between 1965 and 2019, including 22 treated with IPAA and 12 with IRA. Adenoma development was observed in 94.1% of patients; however, no instances of adenocarcinoma were reported, and no additional surgeries were required during the follow-up period (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Both the IPAA and IRA groups underwent intensive annual and 6-month endoscopic surveillance, respectively, during the follow-up. The findings of this previous retrospective study highlight that adenomas can develop following both IRA and IPAA. As such, postoperative endoscopic surveillance is essential for all patients, and those undergoing IRA require more frequent monitoring due to the retained rectal mucosa. Both the Clinical Practice Guidelines of the ASCRS and findings from a recent systematic review indicate that colonoscopy should be performed every 6\u0026ndash;12 months for patients who have received IRA (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA meta-analysis demonstrated that IRA results in superior bowel function compared with IPAA. Patients who underwent IRA reported fewer daily bowel movements, lower rates of nighttime defecation, and a lower incidence of fecal incontinence than those who underwent IPAA. Moreover, IRA was associated with fewer social restrictions (4% vs. 14%) and comparable rates of sexual dysfunction and dietary limitations to IPAA. These functional advantages make IRA a compelling surgical option for patients with FAP and a limited rectal polyp burden, particularly those who prioritize the preservation of bowel function and quality of life (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMaehata \u003cem\u003eet al\u003c/em\u003e. retrospectively analyzed 27 patients with FAP who underwent IRA between 1990 and 2004. During the follow-up period, 10 patients developed rectal cancer (37.0%), indicating a substantial risk of cancer in the rectal remnant (CRR) following IRA (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The cumulative incidence of CRR following IRA has been reported as 8%, 19%, and 57% at 10, 20, and 30 years, respectively. Although IRA is technically less complex than IPAA, it is associated with a significantly higher long-term risk of CRR, particularly without rigorous postoperative surveillance. Therefore, individualized, long-term monitoring is critical to ensure early detection and timely management of CRR, especially in high-risk patients, given that the risk of malignant transformation increases substantially over time. In a separate retrospective analysis of 37 patients with FAP, Sasaki \u003cem\u003eet al\u003c/em\u003e. reported that although IRA was associated with a higher incidence of rectal cancer compared with IPAA, it offered superior preservation of anal function, supporting its use in carefully selected patients with a limited rectal polyp burden to maintain bowel function and quality of life (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Nevertheless, the risk of metachronous rectal cancer increases over time, underscoring the need for intensive endoscopic surveillance (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePrevious animal studies have demonstrated that silymarin, a polyphenolic flavonoid derived from milk thistle (Silybum marianum), possesses promising chemopreventive properties against CRC (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). In azoxymethane-treated rats, silymarin reduced aberrant crypt foci and colonic adenocarcinomas by increasing detoxifying enzymes and lowering β-glucuronidase and prostaglandin E2 levels. In \u003cem\u003eAPC\u003c/em\u003e\u003csup\u003emin/+\u003c/sup\u003e mice, silymarin inhibited microbial β-glucuronidase, preventing dysbiosis and tumor formation (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). These findings suggest that silymarin can modulate gut microbiota and tumorigenic pathways, warranting further clinical research. Therefore, in addition to close colonoscopic surveillance, we administered silymarin as a chemopreventive agent to all patients except Patient 2.\u003c/p\u003e\u003cp\u003eAlthough current evidence supporting the use of silymarin to prevent CRC and polyps is primarily derived from animal models, its favorable safety profile prompted us to administer silymarin under close monitoring of patients\u0026rsquo; long-term clinical outcomes. We anticipate that future studies with more robust clinical data can contribute to validating the efficacy of silymarin in this context; the current lack of such data remains a major limitation. Prospective, multicenter randomized controlled trials are needed to evaluate the efficacy, optimal dosing, safety, and long-term outcomes of silymarin in patients at high risk of CRC and polyps. Biomarker-guided approaches may elucidate the role of silymarin in precision chemoprevention strategies.\u003c/p\u003e\u003cp\u003eThe small sample size, single-center design, and relatively short follow-up period of our study precluded comprehensive long-term risk assessment and may limit the generalizability of our findings. Additionally, only three of the seven patients included consented to genetic testing. Given that patients with FAP\u0026mdash;particularly those under 30 years of age\u0026mdash;require lifelong surveillance to monitor disease progression and prevent malignant transformation, the limited follow-up duration in this study further restricted the evaluation of long-term outcomes. To improve FAP management and surveillance strategies, future studies should include larger, multicenter cohorts, expansive genetic analyses, and direct comparisons between IRA and IPAA.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated that subtotal colectomy with IRA, when combined with intensive endoscopic surveillance, can effectively manage FAP by preserving rectal function and enabling timely detection and treatment of adenomas. Given the higher long-term risk of rectal cancer associated with IRA compared with IPAA, sustained surveillance remains essential. Further multicenter studies and direct comparative analyses between IRA and IPAA are warranted to optimize surgical decision-making and long-term management strategies for patients with FAP.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eFAP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFamilial Adenomatous Polyposis\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIRA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIleorectal Anastomosis\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIPAA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIleal Pouch-Anal Anastomosis\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCRR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCancer in the Rectal Remnant\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eAAV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAnorectal Anal Verge\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eAPC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAdenomatous Polyposis Coli\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/h2\u003e\n\u003cp\u003eThe study was approved by the Institutional Review Board of Kaohsiung Medical University Hospital (approval no. KMUHIRB-E(I)-20230267), which waived the requirement for obtaining written informed consent due to the retrospective design of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe requirement for written informed consent for publication was waived by the Institutional Review Board of Kaohsiung Medical University Hospital due to the retrospective nature of the study. No identifiable patient data are presented in this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interest with regard to the content of this article.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe authors received no specific funding for this study.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eThe authors confirm contribution to the paper as follows: study conception and design: Jaw-Yuan Wang, Hsiang-Lin Tsai; data collection: Ching-Wen Huang, Wei-Chih Su, Tsung-Kun Chang; analysis and interpretation of results: Po-Jung Chen, Yen-Cheng Chen ; draft manuscript preparation: Chi-Han Yang. All authors reviewed the results and approved the final version of the manuscript.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThis work was supported by grants through funding from the National Science and Technology Council (MOST 111-2314-B-037-070-MY3, NSTC 112-2314-B-037-050-MY3, NSTC 113-2321-B-037-006, NSTC 113-2314-B-037-057, NSTC 114-2314-B-037-103-MY3, NSTC 114-2321-B-037-003) and the Ministry of Health and Welfare (MOHW113-TDU-B-222-134014) and funded by the health and welfare surcharge of on tobacco products, and the Kaohsiung Medical University Hospital (KMUH112-2R37, KMUH112-2R38, KMUH112-2R39, KMUH112-2M27, KMUH112-2M28, KMUH112-2M29, KMUH113-2R31, KMUH113-2R32, KMUH113-2R33, KMUH113-3M58, KMUH113-3M59, KMUH-S11303, KMUH-SH11309, KMUH-SI11327), Kaohsiung Medical University Research Center Grant (KMU-TC113A04) and National Tsing Hua University-Kaohsiung Medical University Joint Research Project (NTHU-KMU-KT114P008). In addition, this study was supported by the Grant of Taiwan Precision Medicine Initiative and Taiwan Biobank, Academia Sinica, Taiwan, R.O.C.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe Illumina sequencing was performed by a commercial genetic testing company (Invitae). The identified variants have been submitted to ClinVar, a publicly available database. The ClinVar entries for the relevant patients are as follows:Patient 3: [https://www.ncbi.nlm.nih.gov/clinvar/variation/88913/](https:/www.ncbi.nlm.nih.gov/clinvar/variation/88913)Patient6: [https://www.ncbi.nlm.nih.gov/clinvar/variation/1002757/?oq=NM\\_000038.5:c.-30266G%3EA\u0026amp;amp;m=NM\\_001127511.3(APC):c.-40G%3EA](https:/www.ncbi.nlm.nih.gov/clinvar/variation/1002757/?oq=NM_000038.5:c.-30266G%3EA\u0026amp;m=NM_001127511.3(APC):c.-40G%3EA)The raw sequencing data are not publicly available due to restrictions associated with the use of a third-party clinical testing service.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZaffaroni G, Mannucci A, Koskenvuo L, De Lacy B, Maffioli A, Bisseling T, Half E, Cavestro GM, Valle L, \u003cem\u003eet al.\u003c/em\u003e: Updated European guidelines for clinical management of familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), gastric adenocarcinoma, proximal polyposis of the stomach (GAPPS) and other rare adenomatous polyposis syndromes: a joint EHTG-ESCP revision. British Journal of Surgery 111: znae070, 2024.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSteinberger AE, Westfal ML and Wise PE: Surgical Decision-Making in Familial Adenomatous Polyposis. Clin Colon Rectal Surg 37: 191\u0026ndash;197, 2024.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMonahan KJ, Bradshaw N, Dolwani S, Desouza B, Dunlop MG, East JE, Ilyas M, Kaur A, Lalloo F, \u003cem\u003eet al.\u003c/em\u003e: Guidelines for the management of hereditary colorectal cancer from the British Society of Gastroenterology (BSG)/Association of Coloproctology of Great Britain and Ireland (ACPGBI)/United Kingdom Cancer Genetics Group (UKCGG). Gut 69: 411\u0026ndash;444, 2020.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHerzig D, Hardimann K, Weiser M, Yu N, Paquette I, Feingold DL and Steele SR: The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Inherited Polyposis Syndromes. Diseases of the Colon \u0026amp; Rectum 60: 881\u0026ndash;894, 2017.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTajika M, Tanaka T, Oonishi S, Yamada K, Kamiya T, Mizuno N, Kuwahara T, Okuno N, Haba S, \u003cem\u003eet al.\u003c/em\u003e: Endoscopic Management of Adenomas in the Ileal Pouch and the Rectal Remnant after Surgical Treatment in Familial Adenomatous Polyposis. JCM 11: 3562, 2022.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAziz O, Athanasiou T, Fazio VW, Nicholls RJ, Darzi AW, Church J, Phillips RKS and Tekkis PP: Meta-analysis of observational studies of ileorectal \u003cem\u003eversus\u003c/em\u003e ileal pouch\u0026ndash;anal anastomosis for familial adenomatous polyposis. British Journal of Surgery 93: 407\u0026ndash;417, 2006.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMaehata Y, Esaki M, Nakamura S, Hirahashi M, Ueki T, Iida M, Kitazono T and Matsumoto T: Risk of cancer in the rectal remnant after ileorectal anastomosis in patients with familial adenomatous polyposis: S ingle center experience. Digestive Endoscopy 27: 471\u0026ndash;478, 2015.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSasaki K, Nozawa H, Kawai K, Murono K, Emoto S, Kishikawa J, Ishii H, Yokoyama Y, Abe S, \u003cem\u003eet al.\u003c/em\u003e: Risk of extracolonic malignancies and metachronous rectal cancer after colectomy and ileorectal anastomosis in familial adenomatous polyposis. Asian Journal of Surgery 45: 396\u0026ndash;400, 2022.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMenahem B, Alves A, Regimbeau JM and Sabbagh C: Colorectal family polyadenomatous diseases. What management in 2020? Journal of Visceral Surgery 157: 127\u0026ndash;135, 2020.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKohno H, Tanaka T, Kawabata K, Hirose Y, Sugie S, Tsuda H and Mori H: Silymarin, a naturally occurring polyphenolic antioxidant flavonoid, inhibits azoxymethane-induced colon carcinogenesis in male F344 rats. Intl Journal of Cancer 101: 461\u0026ndash;468, 2002.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng KW, Tseng CH, Chen IJ, Huang BC, Liu HJ, Ho KW, Lin WW, Chuang CH, Huang MY, \u003cem\u003eet al.\u003c/em\u003e: Inhibition of gut microbial β-glucuronidase effectively prevents carcinogen-induced microbial dysbiosis and intestinal tumorigenesis. Pharmacological Research 177: 106115, 2022.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"colonoscopic surveillance, familial adenomatous polyposis, ileorectal anastomosis","lastPublishedDoi":"10.21203/rs.3.rs-7934102/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7934102/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eFamilial adenomatous polyposis (FAP) is an inherited disorder caused by mutations in the adenomatous polyposis coli gene, causing numerous colorectal adenomas to develop. If left untreated, FAP is associated with a nearly 100% lifetime risk of colorectal cancer. Subtotal colectomy with ileorectal anastomosis (IRA) is a surgical option that preserves rectal function but necessitates intensive postoperative surveillance due to the residual risk of malignancy in the retained rectum.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis retrospective study included seven patients with FAP who underwent subtotal colectomy with IRA at a single institution between 2015 and 2024. Postoperative management involved intensive colonoscopic surveillance and polypectomy of rectal lesions. Clinical and pathological data were analyzed, including the incidence of residual rectal polyps, bowel function, and clinical outcomes.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eAll patients developed residual rectal polyps during follow-up, which were successfully removed through polypectomy without evidence of malignant transformation. Bowel function was well-preserved in all patients, with rectal lengths ranging from 10 to 15 cm. Silymarin, a natural polyphenolic flavonoid with potential chemopreventive effects, was administered to six of the seven patients, among whom it was well-tolerated. The long-term effects of silymarin are under evaluation during ongoing follow-up.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eSubtotal colectomy with IRA, combined with regular colonoscopic surveillance and timely polypectomy, can effectively manage FAP and preserve bowel function. Silymarin may be a promising adjunctive chemopreventive agent; however, further clinical trials are needed to validate its efficacy and safety in human populations. These findings highlight the necessity of individualized surgical planning and vigilant long-term surveillance in FAP management.\u003c/p\u003e","manuscriptTitle":"Outcomes of Subtotal Colectomy with Ileorectal Anastomosis and Regular Colonoscopic Surveillance of Polypectomy in Patients with Familial Adenomatous Polyposis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-26 10:53:42","doi":"10.21203/rs.3.rs-7934102/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"080a0dd7-d96b-49b4-a905-a10a00050f74","owner":[],"postedDate":"November 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-20T03:55:06+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-26 10:53:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7934102","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7934102","identity":"rs-7934102","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}