Wilms' Tumor: Distribution, Demographics, and Outcomes in Sanaa City

Wilms' Tumor: Distribution, Demographics, and Outcomes in Sanaa City | 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 Wilms' Tumor: Distribution, Demographics, and Outcomes in Sanaa City Aziz Shamsan, Khaled Alkohlany, Majdi Alshami, Ahmed Farei, Wael Alsaqaf, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7334363/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: Wilms’ tumor (WT) is the most common pediatric renal malignancy, accounting for approximately 90% of kidney tumors in children. While outcomes in high-income countries exceed 90% survival, data from low-resource settings remain scarce, and no published series from Yemen exist. Objective: To describe the demographic distribution, clinical presentation, management patterns, and short-term outcomes of pediatric WT cases in Sana’a City, Yemen. Methods: This prospective study included all children aged ≤15 years with histologically confirmed WT, managed across governmental and private hospitals in Sana’a between January 2021 and December 2022. Demographic, clinical, radiological, surgical, and histopathological data were collected using a standardized case report form. Tumors were staged according to the Children’s Oncology Group (COG) criteria. Treatment modalities and outcomes, including event-free survival and overall survival at two years. Results: Fourteen patients were identified, with a male predominance (71.4%) and mean age 3.6 ± 3.5 years. Abdominal mass was the most common presentation (85.7%). Right-sided tumors predominated (64.3%), and all lesions were solid. According to COG staging, 35.7% were Stage I, 50.0% Stage II, and 14.3% Stage III; all had favorable histology. Preoperative chemotherapy was administered in 28.6% of patients, all underwent surgical resection, and 21.4% received postoperative chemotherapy. No patient received radiotherapy. At a median follow-up of 15 months (range: 7–22), 92.9% achieved complete remission, and one patient (7.1%) relapsed and died 18 months postoperatively. Conclusion: Pediatric WT in Sana’a City presents predominantly in early stages with favorable histology, but access to multimodal therapy—particularly radiotherapy—remains limited. The high remission rate is encouraging, but long-term follow-up and resource optimization are essential to improve outcomes and align with international standards. Wilms’ tumor nephroblastoma Yemen pediatric oncology COG staging survival outcomes Figures Figure 1 Figure 2 Introduction Wilms’ tumor (WT), or nephroblastoma, accounts for over 90% of pediatric renal malignancies and represents approximately 3.2–11.1% of childhood cancers worldwide, with marked epidemiologic variation between regions and ethnic groups. The age-standardized incidence rate (ASR) ranges from 4.1–5.4 per million in Asian populations to 9.1–9.8 per million in North America and Europe, with the highest rates among Black populations (10.9 per million). In children under five, WT predominates, peaking between 2 and 3 years of age [ 1 – 3 ]. WT arises from remnants of the metanephric blastema, reflecting abnormal persistence of embryonic renal precursor cells. While most cases are sporadic, WT may be associated with congenital anomaly syndromes such as WAGR (Wilms’ tumor, Aniridia, Genitourinary anomalies, and mental Retardation), Denys–Drash, and Beckwith–Wiedemann. At the molecular level, loss of heterozygosity (LOH) at chromosomes 1p and 16q and gain of chromosome 1q have been linked to poorer outcomes in favorable-histology WT. Other reported alterations include LOH at 4q and 14q, MYCN amplification, and changes at 7p, although these markers are not yet standard in clinical prognostic models [ 4 – 7 ]. Treatment success in high-income countries (HICs) exceeds 90% overall survival (OS), largely due to structured, multidisciplinary protocols from major cooperative groups. The Children’s Oncology Group (COG) favors upfront nephrectomy followed by adjuvant therapy, whereas the International Society of Pediatric Oncology (SIOP) advocates preoperative chemotherapy to reduce tumor size before surgery. Despite differences in sequencing, both approaches yield comparable long-term survival, highlighting the effectiveness of risk-adapted strategies and the importance of minimizing long-term treatment toxicity [ 8 – 10 ]. In low- and middle-income countries (LMICs), survival remains significantly lower—often 25–53%—due to delayed presentation, advanced stage at diagnosis, limited access to imaging and pathology services, treatment abandonment, and inconsistent delivery of chemotherapy or radiotherapy. In some sub-Saharan and Central Asian series, 60–80% of patients present with stage III or IV disease, and pathology review is often unavailable or incomplete [ 11 – 13 ]. To our knowledge, there are no published studies on pediatric WT in Yemen to date. This prospective study aims to address this gap by investigating the epidemiological characteristics of WT in Sanaa City, Yemen, and to contribute to improving the prognosis and quality of life for children with WT in our country. This study analyzes the clinical features, treatment results, outcomes, and factors relevant to the management of patients with WT in Yemen. Patients and Methods Study Design and Setting We conducted a prospective, multicenter cohort study across all governmental and private hospitals in Sanaa City, Yemen, from January 2021 to December 2022. The study aimed to identify all newly diagnosed pediatric WT cases in the city during the study period. Patients: Children aged ≤15 years with histologically confirmed Wilms’ tumor, verified by local pathology review when available, were included in the study. Eligible participants were enrolled after obtaining informed consent from a parent or legal guardian. Patients with non-renal tumors, those without histopathologic confirmation, or with incomplete diagnostic records were excluded. Data Collection Data were obtained using a standardized case report form and included demographic information (age, sex, and family history of urogenital tumors) and clinical characteristics such as presenting complaints, symptom duration, abdominal mass size, hematuria, and hypertension. Imaging studies comprised abdominal ultrasound, contrast-enhanced CT and/or MRI, and chest CT to assess local tumor extension and the presence of distant metastases. Surgical findings recorded included tumor laterality, size, invasion of surrounding structures, and lymph node involvement. Histopathological evaluation was performed on surgical resection specimens and classified tumors according to Children’s Oncology Group (COG) criteria into favorable-histology and anaplastic subtypes; staging was assigned using the COG staging system [14]. Treatment details captured the type of surgical intervention (nephrectomy or biopsy), chemotherapy regimens and timing (including any patients who received preoperative chemotherapy), and use of radiotherapy when indicated. Outcomes documented were treatment completion, abandonment, relapse, and two-year event-free survival and overall survival. Follow-Up Patients were monitored weekly during the early postoperative phase and every three months thereafter, with clinical assessment and imaging as indicated to detect relapse or progression. Statistical Analysis Data were analyzed using SPSS version 28.0. Continuous variables were summarized as means with standard deviation (SD), and categorical variables as frequencies and percentages. Ethical Considerations The study was approved by the scientific committee of the Arab Board of Urology in Sana’a City, Yemen. All participants’ data were anonymized to ensure confidentiality, and informed written consent was obtained from parents or guardians. Results During the study period, a total of 14 pediatric patients were diagnosed with Wilms’ tumor. The majority were male (n = 10, 71.4%), with females accounting for 28.6% (n = 4). Half of the cohort (n = 7, 50.0%) were aged between 0.5 and 2 years, followed by 3–4 years (n = 4, 28.6%) and 5–18 years (n = 3, 21.4%). The mean age was 3.6 ± 3.5 years, ranging from 7 months to 13 years ( Table 1 ). Table 1. Demographic characteristics of patients with Wilms’ tumor. Variable Category n % Gender Male 10 71.4 Female 4 28.6 Age group 0.5–2 years 7 50.0 3–4 years 4 28.6 5–18 years 3 21.4 The most common presenting symptom was abdominal mass (n = 12, 85.7%), followed by abdominal distension (n = 4, 28.6%) and abdominal pain (n = 2, 14.3%) ( Figure 1 ). Radiological evaluation revealed that the majority had right-sided tumors (n = 9, 64.3%), while 5 patients (35.7%) had left-sided tumors; none had bilateral disease. Tumor volume exceeded 500 mL in 3 patients (21.4%), while 11 (78.6%) had tumors smaller than 500 mL. All tumors were solid in consistency. Local invasion was present in 4 cases (28.6%), retroperitoneal lymph node metastasis in 2 cases (14.3%), and distant metastasis in 1 case (7.1%) ( Table 2 ). Table 2. Radiological findings of Wilms’ tumor cases. Parameter Category n % Tumor site Right 9 64.3 Left 5 35.7 Tumor volume 500 mL 3 21.4 Consistency Solid 14 100.0 Local invasion Present 4 28.6 Absent 10 71.4 Retroperitoneal LN metastasis Present 2 14.3 Absent 12 85.7 Distant metastasis Present 1 7.1 Absent 13 92.9 Regarding treatment, 4 patients (28.6%) received preoperative chemotherapy, while all underwent surgical excision. Postoperative chemotherapy was administered to 3 patients (21.4%), and none received postoperative radiotherapy ( Table 3 ). Table 3. Treatment modalities for Wilms’ tumor patients. Treatment modality n % Preoperative chemotherapy 4 28.6 Surgical excision 14 100.0 Postoperative chemotherapy 3 21.4 Postoperative radiotherapy 0 0 Histopathological evaluation was performed on all resection specimens according to the Children’s Oncology Group (COG) classification. Favorable histology was identified in all patients, with no anaplastic tumors detected. Based on the COG staging system, 5 patients (35.7%) were classified as Stage I, 7 patients (50.0%) as Stage II, and 2 patients (14.3%) as Stage III. No Stage IV or Stage V cases were observed. The distribution of histological subtypes and the proportion of epithelial, blastemal, and necrotic components are detailed in Table 4 . Table 4. Histopathological features of Wilms’ tumor cases classified according to COG criteria Case no. COG Stage Histological subtype Epithelial (%) Blastemal (%) Tumor necrosis (%) 1 II Mixed 70 10 20 2 I Mixed 6 4 90 3 III Mixed 10 90 0 4 III Mixed 70 10 20 5 II Mixed 70 10 20 6 I Mixed 6 4 90 7 II Mixed 50 30 20 8 II Mixed 5 6 89 9 II Mixed 3 12 85 10 I Mixed 20 5 75 11 I Mixed 10 60 30 12 I Mixed 30 60 10 13 II Mixed 70 20 10 14 II Mixed 30 60 10 Follow-up data were available for all patients. Thirteen children (92.9%) achieved complete remission, with follow-up durations ranging from 7 to 22 months. One patient experienced relapse during chemotherapy and subsequently died 18 months after surgery ( Figure 2 ). Discussion In this prospective cohort of 14 pediatric patients with Wilms’ tumor (WT) in Sanaa City, Yemen, the male predominance (71.4%) and mean age of 3.6 years align with global trends, where WT typically presents before the age of five and shows a slight male excess【1,2】. Studies from sub-Saharan Africa and the Middle East have reported similar male predominance ranging from 55–70%【3,15】. In contrast, large datasets from North America and Europe have shown a nearly equal sex distribution【9】. The peak age group in our cohort (0.5–2 years) was slightly younger than the typical peak incidence at 2–3 years【8】, possibly reflecting earlier tumor detection in symptomatic children despite overall diagnostic delays in low-resource settings. The most common presenting symptom in our study was an abdominal mass (85.7%), followed by abdominal distension (28.6%) and abdominal pain (14.3%). These findings are consistent with reports from Nigeria, Sudan, and Saudi Arabia, where an abdominal mass is the leading presentation in 80–95% of WT cases【3,11,12】. The absence of gross hematuria in our series is notable, as hematuria has been reported in up to 25% of cases【16】. This variation may relate to differences in tumor location, degree of calyceal involvement, or underreporting of mild hematuria in young children. Radiologically, right-sided tumors predominated (64.3%), consistent with some African and Asian reports【15,12】, though most literature suggests no significant lateral preference【8,13】. Tumor size exceeded 500 mL in 21.4% of our patients, which is smaller than the > 50% large-tumor rate reported in delayed-diagnosis settings such as Malawi【3】. Local invasion (28.6%) and retroperitoneal lymph node metastasis (14.3%) in our study were within the range reported in African series (20–40% and 10–20%, respectively)【15,12】. Only one patient (7.1%) had distant metastasis, markedly lower than the 15–30% reported in high-stage presentations in LMICs【3,11】, possibly due to earlier surgical intervention or under-detection from limited imaging access. With respect to treatment, only 28.6% of our patients received preoperative chemotherapy, compared to near-universal preoperative chemotherapy in SIOP-based protocols【9,10】. All patients underwent surgical excision, but only 21.4% received postoperative chemotherapy. In contrast, adherence to complete multimodal therapy in high-income countries exceeds 95%【8,10】, contributing to survival rates above 90%. Treatment abandonment and protocol deviations in LMICs have been strongly associated with poorer outcomes【3,17】. Histopathological staging in our cohort showed 35.7% in stage I, 50% in stage II, and 14.3% in stage III, with no stage IV or V disease. This distribution differs from other LMIC reports, where 40–70% present with stage III–V disease【15,11】. The relatively higher proportion of lower-stage disease in our study may reflect selection bias or limited diagnostic staging resources. All cases were favorable histology, which is consistent with the fact that unfavorable histology occurs in only 5–10% of WT globally【8】, though its detection in LMICs may be limited by pathology constraints【17】. Our survival rate of 92.9% over a median follow-up of up to 22 months is encouraging and exceeds typical LMIC survival rates (25–60%)【3,15】. This figure approaches HIC outcomes, though the short follow-up period and small sample size limit interpretation. Only one patient relapsed and subsequently died, reflecting a relapse rate (7.1%) well below the 15–20% commonly reported【6,8】. However, longer follow-up is necessary to capture late relapses and late treatment-related mortality. Overall, our findings underscore both encouraging aspects and critical challenges in WT management in Yemen. While early-stage presentation and high short-term survival are promising, low uptake of standardized multimodal therapy, absence of radiotherapy, and limited preoperative chemotherapy use highlight systemic gaps. Addressing these requires improved diagnostic capacity, adoption of unified treatment protocols (COG or SIOP), and ensuring chemotherapy availability. Conclusion Pediatric WT in Sana’a City presents predominantly in early stages with favorable histology, but access to multimodal therapy—particularly radiotherapy—remains limited. The high remission rate is encouraging, but long-term follow-up and resource optimization are essential to improve outcomes and align with international standards. Abbreviations WT: Wilms’ tumor; COG: Children’s Oncology Group; SIOP: International Society of Pediatric Oncology; LMIC: Low- and Middle-Income Country; HIC: High-Income Country; OS: Overall Survival; EFS: Event-Free Survival. Declarations Ethics Approval and Consent to Participate This study was approved by the Scientific Committee of the Arab Board of Urology, Sana’a, Yemen (Approval Code: GMH-IRB-2024-WT-02). Written informed consent was obtained from all parents/guardians prior to enrollment. All procedures adhered to the Declaration of Helsinki. Consent for Publication Parents/guardians provided written consent for anonymized data publication. No identifiable patient images or details are included. Availability of Data and Materials De-identified datasets are available from the corresponding author ( [email protected] ) upon reasonable request. Study protocols and case report forms are archived at the General Military Hospital, Sana’a. Competing Interests The authors declare no competing interests, financial or non-financial, related to this work. Funding This study received no external funding. Institutional support was provided by the Arab Board of Health Specialization, Sana’a . Authors’ Contributions 1. Aziz Shamsan Conceptualization, data acquisition, manuscript drafting, and final approval. 2. Khaled Alkohlany: Study design, supervision, critical revision, and accountability. 3. Majdi Alshami: Supervision, surgical management, follow-up data collection. 4. Ahmed Farei: Data collection, analysis, manuscript drafting. 5. Wael Alsaqaf: Surgical management, follow-up data collection. 6. Abdullah Al-Sakkaf: Imaging analysis, manuscript review. 7. Nasser Albaddai: Statistical analysis, manuscript review, and final approval. Acknowledgements We thank the Arab Board of Health Specialization for ethical oversight and the General Military Hospital (GMH), Sana’a for clinical infrastructure. We acknowledge the pathology and radiology teams at GMH for diagnostic support, and nursing staff for patient care. Finally, we honor the resilience of our patients and families amid Yemen’s humanitarian crisis. References Nakata K, Colombet M, Stiller CA, Pritchard-Jones K, Steliarova-Foucher E, IICC-3 Contributors. Incidence of childhood renal tumours: An international population-based study. Int J Cancer. 2020;147(12):3313-3327. Libes J, Hol J, Neto JCA, et al. Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges. Pediatr Blood Cancer. 2023;70(Suppl 2):e30343. Cunningham ME, Klug TD, Nuchtern JG, et al. Global disparities in Wilms tumor. J Surg Res. 2020;247:34-51. Beckwith JB. Wilms' tumor and other renal tumors of childhood: A selective review from the National Wilms' Tumor Study Pathology Center. Hum Pathol. 1983;14(6):481-492. Grundy PE, Breslow NE, Li S, et al. Loss of heterozygosity for chromosomes 1p and 16q is an adverse prognostic factor in favorable-histology Wilms tumor: A report from the National Wilms Tumor Study Group. J Clin Oncol. 2005;23(29):7312-7321. Gratias EJ, Dome JS, Jennings LJ, et al. Association of chromosome 1q gain with inferior survival in favorable-histology Wilms tumor: A report from the Children’s Oncology Group. J Clin Oncol. 2016;34(26):3189-3194. Chagtai T, Zill C, Dainese L, et al. Gain of 1q as a prognostic biomarker in Wilms tumors treated with preoperative chemotherapy in the International Society of Paediatric Oncology WT 2001 trial. J Clin Oncol. 2016;34(26):3195-3203. Dome JS, Graf N, Geller JI, et al. Advances in Wilms tumor treatment and biology: Progress through international collaboration. J Clin Oncol. 2015;33(27):2999-3007. van den Heuvel-Eibrink MM, Hol JA, Pritchard-Jones K, et al. Position paper: Rationale for the treatment of Wilms tumour in the UMBRELLA SIOP-RTSG 2016 protocol. Nat Rev Urol. 2017;14(12):743-752. Fernandez CV, Mullen EA, Chi YY, et al. Outcome and prognostic factors in stage III favorable-histology Wilms tumor: A report from the Children's Oncology Group study AREN0532. J Clin Oncol. 2018;36(3):254-261. Israels T, Moreira C, Scanlan T, et al. SIOP PODC: Recommendations for Wilms tumour in sub-Saharan Africa. Pediatr Blood Cancer. 2013;60(1):5-11. Hadley GP. The management of Wilms' tumour in Africa. Ann Trop Paediatr. 2011;31(2):141-151. de Aguirre-Neto JC, de Camargo B, van Tinteren H, et al. International comparisons of clinical demographics and outcomes in the International Society of Pediatric Oncology Wilms Tumor 2001 Trial and Study. JCO Glob Oncol. 2022;8:e2100425. Vujanić GM, Parsons LN, D'Hooghe E, Treece AL, Collini P, Perlman EJ. Pathology of Wilms' tumour in International Society of Paediatric Oncology (SIOP) and Children's oncology group (COG) renal tumour studies: similarities and differences. Histopathology. 2022 Jun;80(7):1026-37. Ekenze SO, Okafor OC, Obasi AA, et al. Wilms tumor in Africa: A systematic review of management challenges and outcome in two decades. Pediatr Blood Cancer. 2020;67(9):e28695. Breslow NE, Olshan A, Beckwith JB, Green DM. Epidemiology of Wilms tumor. Med Pediatr Oncol. 1993;21(3):172-181. Elhassan MM, Suliman SO, Awooda HA, et al. Management and outcome of Wilms' tumor in Sudan: Challenges and future prospects. Afr J Paediatr Surg. 2021;18(1):1-6. 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. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7334363","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":512668258,"identity":"7a86bfa5-4fb7-4be0-9171-2e20f2ad096b","order_by":0,"name":"Aziz Shamsan","email":"","orcid":"","institution":"Urology Department, General Military Hospital (GMH)","correspondingAuthor":false,"prefix":"","firstName":"Aziz","middleName":"","lastName":"Shamsan","suffix":""},{"id":512668262,"identity":"4e3c27ab-82d5-43a2-8ac8-5ad5266b7b17","order_by":1,"name":"Khaled Alkohlany","email":"","orcid":"","institution":"Sana'a University","correspondingAuthor":false,"prefix":"","firstName":"Khaled","middleName":"","lastName":"Alkohlany","suffix":""},{"id":512668264,"identity":"801c2a94-50b2-4093-a162-c9a0a65a1315","order_by":2,"name":"Majdi Alshami","email":"","orcid":"","institution":"Urology Department, General Military Hospital (GMH)","correspondingAuthor":false,"prefix":"","firstName":"Majdi","middleName":"","lastName":"Alshami","suffix":""},{"id":512668267,"identity":"42fa9559-a0b9-48a7-b846-e354448c5b5b","order_by":3,"name":"Ahmed Farei","email":"","orcid":"","institution":"Urology Department, General Military Hospital (GMH)","correspondingAuthor":false,"prefix":"","firstName":"Ahmed","middleName":"","lastName":"Farei","suffix":""},{"id":512668269,"identity":"30cfeaf2-3854-4d57-beb3-653b72fd2be2","order_by":4,"name":"Wael Alsaqaf","email":"","orcid":"","institution":"Urology Department, General Military Hospital (GMH)","correspondingAuthor":false,"prefix":"","firstName":"Wael","middleName":"","lastName":"Alsaqaf","suffix":""},{"id":512668271,"identity":"b574bd88-e52c-4b28-b263-12c920f66194","order_by":5,"name":"Abdullah Al-Sakkaf","email":"","orcid":"","institution":"21 September University of Medical and Applied Sciences","correspondingAuthor":false,"prefix":"","firstName":"Abdullah","middleName":"","lastName":"Al-Sakkaf","suffix":""},{"id":512668273,"identity":"f0d8eecc-942a-4a77-93c1-c791c8de0b50","order_by":6,"name":"Nasser Albaddai","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIiWNgGAWjYLCChw0MjA0HGBsfANk8fERpSYRoaTYAaWEjQQsDmwSIQ1CLOfvxhx8Sd9jJ9h0/3Fb5NcdOho2B+eGjG3i0WPbkGEsknkk2nnkmse227LZkoMPYjI1z8GgxOJDDIJHYxpy44QBQi+Q2ZqAWHjZpvFrOP3/8I7GtPnHD+YdtxZLb6onQciPBDGjL4cQNNxLbGD9uO0yMljdmFolnjhvPvPGwWZpx23EeNmZCfjmf/vjGxx3Vsn3n0x9+/Lmt2p6fvfnhY3xaUAAzD5gkVjkIMP4gRfUoGAWjYBSMGAAAVQlSOn6DLBIAAAAASUVORK5CYII=","orcid":"","institution":"Urology Department, General Military Hospital (GMH)","correspondingAuthor":true,"prefix":"","firstName":"Nasser","middleName":"","lastName":"Albaddai","suffix":""}],"badges":[],"createdAt":"2025-08-09 14:08:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7334363/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7334363/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91189150,"identity":"39c517f5-f017-422c-afc6-6b4c07234a57","added_by":"auto","created_at":"2025-09-12 14:26:55","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":69365,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePresenting symptoms among cases\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7334363/v1/c92eb7521bbfab1b5825d917.png"},{"id":91189155,"identity":"441ebcf5-c180-4276-bff7-a970d07f3c64","added_by":"auto","created_at":"2025-09-12 14:26:56","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":82252,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFinal outcome\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7334363/v1/7d8a673d366c8f66d161a30c.png"},{"id":107520187,"identity":"9dd316d3-8353-4b40-ac6c-d6f063124add","added_by":"auto","created_at":"2026-04-22 08:59:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":775243,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7334363/v1/6d5e318e-5c40-4b68-b17c-a314a256ddbf.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Wilms' Tumor: Distribution, Demographics, and Outcomes in Sanaa City","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWilms\u0026rsquo; tumor (WT), or nephroblastoma, accounts for over 90% of pediatric renal malignancies and represents approximately 3.2\u0026ndash;11.1% of childhood cancers worldwide, with marked epidemiologic variation between regions and ethnic groups. The age-standardized incidence rate (ASR) ranges from 4.1\u0026ndash;5.4 per million in Asian populations to 9.1\u0026ndash;9.8 per million in North America and Europe, with the highest rates among Black populations (10.9 per million). In children under five, WT predominates, peaking between 2 and 3 years of age [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eWT arises from remnants of the metanephric blastema, reflecting abnormal persistence of embryonic renal precursor cells. While most cases are sporadic, WT may be associated with congenital anomaly syndromes such as WAGR (Wilms\u0026rsquo; tumor, Aniridia, Genitourinary anomalies, and mental Retardation), Denys\u0026ndash;Drash, and Beckwith\u0026ndash;Wiedemann. At the molecular level, loss of heterozygosity (LOH) at chromosomes 1p and 16q and gain of chromosome 1q have been linked to poorer outcomes in favorable-histology WT. Other reported alterations include LOH at 4q and 14q, MYCN amplification, and changes at 7p, although these markers are not yet standard in clinical prognostic models [\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTreatment success in high-income countries (HICs) exceeds 90% overall survival (OS), largely due to structured, multidisciplinary protocols from major cooperative groups. The Children\u0026rsquo;s Oncology Group (COG) favors upfront nephrectomy followed by adjuvant therapy, whereas the International Society of Pediatric Oncology (SIOP) advocates preoperative chemotherapy to reduce tumor size before surgery. Despite differences in sequencing, both approaches yield comparable long-term survival, highlighting the effectiveness of risk-adapted strategies and the importance of minimizing long-term treatment toxicity [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn low- and middle-income countries (LMICs), survival remains significantly lower\u0026mdash;often 25\u0026ndash;53%\u0026mdash;due to delayed presentation, advanced stage at diagnosis, limited access to imaging and pathology services, treatment abandonment, and inconsistent delivery of chemotherapy or radiotherapy. In some sub-Saharan and Central Asian series, 60\u0026ndash;80% of patients present with stage III or IV disease, and pathology review is often unavailable or incomplete [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTo our knowledge, there are no published studies on pediatric WT in Yemen to date. This prospective study aims to address this gap by investigating the epidemiological characteristics of WT in Sanaa City, Yemen, and to contribute to improving the prognosis and quality of life for children with WT in our country. This study analyzes the clinical features, treatment results, outcomes, and factors relevant to the management of patients with WT in Yemen.\u003c/p\u003e"},{"header":"Patients and Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy Design and Setting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe conducted a prospective, multicenter cohort study across all governmental and private hospitals in Sanaa City, Yemen, from January 2021 to December 2022. The study aimed to identify all newly diagnosed pediatric WT cases in the city during the study period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatients:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChildren aged \u0026le;15 years with histologically confirmed Wilms\u0026rsquo; tumor, verified by local pathology review when available, were included in the study. Eligible participants were enrolled after obtaining informed consent from a parent or legal guardian. Patients with non-renal tumors, those without histopathologic confirmation, or with incomplete diagnostic records were excluded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Collection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData were obtained using a standardized case report form and included demographic information (age, sex, and family history of urogenital tumors) and clinical characteristics such as presenting complaints, symptom duration, abdominal mass size, hematuria, and hypertension. Imaging studies comprised abdominal ultrasound, contrast-enhanced CT and/or MRI, and chest CT to assess local tumor extension and the presence of distant metastases. Surgical findings recorded included tumor laterality, size, invasion of surrounding structures, and lymph node involvement. Histopathological evaluation was performed on surgical resection specimens and classified tumors according to Children\u0026rsquo;s Oncology Group (COG) criteria into favorable-histology and anaplastic subtypes; staging was assigned using the COG staging system [14]. Treatment details captured the type of surgical intervention (nephrectomy or biopsy), chemotherapy regimens and timing (including any patients who received preoperative chemotherapy), and use of radiotherapy when indicated. Outcomes documented were treatment completion, abandonment, relapse, and two-year event-free survival and overall survival.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFollow-Up\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were monitored weekly during the early postoperative phase and every three months thereafter, with clinical assessment and imaging as indicated to detect relapse or progression.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData were analyzed using SPSS version 28.0. Continuous variables were summarized as means with standard deviation (SD), and categorical variables as frequencies and percentages.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Considerations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was approved by the scientific committee of the Arab Board of Urology in Sana\u0026rsquo;a City, Yemen. All participants\u0026rsquo; data were anonymized to ensure confidentiality, and informed written consent was obtained from parents or guardians.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eDuring the study period, a total of 14 pediatric patients were diagnosed with Wilms\u0026rsquo; tumor. The majority were male (n = 10, 71.4%), with females accounting for 28.6% (n = 4). Half of the cohort (n = 7, 50.0%) were aged between 0.5 and 2 years, followed by 3\u0026ndash;4 years (n = 4, 28.6%) and 5\u0026ndash;18 years (n = 3, 21.4%). The mean age was 3.6 \u0026plusmn; 3.5 years, ranging from 7 months to 13 years (\u003cstrong\u003eTable 1\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. Demographic characteristics of patients with Wilms\u0026rsquo; tumor.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"263\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCategory\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e71.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.5\u0026ndash;2 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u0026ndash;4 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5\u0026ndash;18 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe most common presenting symptom was abdominal mass (n = 12, 85.7%), followed by abdominal distension (n = 4, 28.6%) and abdominal pain (n = 2, 14.3%) (\u003cstrong\u003eFigure 1\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eRadiological evaluation revealed that the majority had right-sided tumors (n = 9, 64.3%), while 5 patients (35.7%) had left-sided tumors; none had bilateral disease. Tumor volume exceeded 500 mL in 3 patients (21.4%), while 11 (78.6%) had tumors smaller than 500 mL. All tumors were solid in consistency. Local invasion was present in 4 cases (28.6%), retroperitoneal lymph node metastasis in 2 cases (14.3%), and distant metastasis in 1 case (7.1%) (\u003cstrong\u003eTable 2\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Radiological findings of Wilms\u0026rsquo; tumor cases.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"421\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCategory\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTumor site\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e64.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTumor volume\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;500 mL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e78.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026gt;500 mL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eConsistency\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSolid\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eLocal invasion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e71.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eRetroperitoneal LN metastasis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e85.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDistant metastasis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e92.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eRegarding treatment, 4 patients (28.6%) received preoperative chemotherapy, while all underwent surgical excision. Postoperative chemotherapy was administered to 3 patients (21.4%),\u0026nbsp;and none received postoperative radiotherapy (\u003cstrong\u003eTable 3\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Treatment modalities for Wilms\u0026rsquo; tumor patients.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"308\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTreatment modality\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePreoperative chemotherapy\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSurgical excision\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePostoperative chemotherapy\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePostoperative radiotherapy\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eHistopathological evaluation was performed on all resection specimens according to the \u003cstrong\u003eChildren\u0026rsquo;s Oncology Group (COG)\u003c/strong\u003e classification. Favorable histology was identified in all patients, with no anaplastic tumors detected. Based on the COG staging system, 5 patients (35.7%) were classified as Stage I, 7 patients (50.0%) as Stage II, and 2 patients (14.3%) as Stage III. No Stage IV or Stage V cases were observed. The distribution of histological subtypes and the proportion of epithelial, blastemal, and necrotic components are detailed in \u003cstrong\u003eTable 4\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4. Histopathological features of Wilms\u0026rsquo; tumor cases classified according to COG criteria\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCase no.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCOG Stage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eHistological subtype\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eEpithelial (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBlastemal (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTumor necrosis (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eIII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eIII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e11\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e12\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e13\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e14\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFollow-up data were available for all patients. Thirteen children (92.9%) achieved complete remission, with follow-up durations ranging from 7 to 22 months. One patient experienced relapse during chemotherapy and subsequently died 18 months after surgery (\u003cstrong\u003eFigure 2\u003c/strong\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this prospective cohort of 14 pediatric patients with Wilms\u0026rsquo; tumor (WT) in Sanaa City, Yemen, the male predominance (71.4%) and mean age of 3.6 years align with global trends, where WT typically presents before the age of five and shows a slight male excess【1,2】. Studies from sub-Saharan Africa and the Middle East have reported similar male predominance ranging from 55\u0026ndash;70%【3,15】. In contrast, large datasets from North America and Europe have shown a nearly equal sex distribution【9】. The peak age group in our cohort (0.5\u0026ndash;2 years) was slightly younger than the typical peak incidence at 2\u0026ndash;3 years【8】, possibly reflecting earlier tumor detection in symptomatic children despite overall diagnostic delays in low-resource settings.\u003c/p\u003e\u003cp\u003eThe most common presenting symptom in our study was an abdominal mass (85.7%), followed by abdominal distension (28.6%) and abdominal pain (14.3%). These findings are consistent with reports from Nigeria, Sudan, and Saudi Arabia, where an abdominal mass is the leading presentation in 80\u0026ndash;95% of WT cases【3,11,12】. The absence of gross hematuria in our series is notable, as hematuria has been reported in up to 25% of cases【16】. This variation may relate to differences in tumor location, degree of calyceal involvement, or underreporting of mild hematuria in young children.\u003c/p\u003e\u003cp\u003eRadiologically, right-sided tumors predominated (64.3%), consistent with some African and Asian reports【15,12】, though most literature suggests no significant lateral preference【8,13】. Tumor size exceeded 500 mL in 21.4% of our patients, which is smaller than the \u0026gt;\u0026thinsp;50% large-tumor rate reported in delayed-diagnosis settings such as Malawi【3】. Local invasion (28.6%) and retroperitoneal lymph node metastasis (14.3%) in our study were within the range reported in African series (20\u0026ndash;40% and 10\u0026ndash;20%, respectively)【15,12】. Only one patient (7.1%) had distant metastasis, markedly lower than the 15\u0026ndash;30% reported in high-stage presentations in LMICs【3,11】, possibly due to earlier surgical intervention or under-detection from limited imaging access.\u003c/p\u003e\u003cp\u003eWith respect to treatment, only 28.6% of our patients received preoperative chemotherapy, compared to near-universal preoperative chemotherapy in SIOP-based protocols【9,10】. All patients underwent surgical excision, but only 21.4% received postoperative chemotherapy. In contrast, adherence to complete multimodal therapy in high-income countries exceeds 95%【8,10】, contributing to survival rates above 90%. Treatment abandonment and protocol deviations in LMICs have been strongly associated with poorer outcomes【3,17】.\u003c/p\u003e\u003cp\u003eHistopathological staging in our cohort showed 35.7% in stage I, 50% in stage II, and 14.3% in stage III, with no stage IV or V disease. This distribution differs from other LMIC reports, where 40\u0026ndash;70% present with stage III\u0026ndash;V disease【15,11】. The relatively higher proportion of lower-stage disease in our study may reflect selection bias or limited diagnostic staging resources. All cases were favorable histology, which is consistent with the fact that unfavorable histology occurs in only 5\u0026ndash;10% of WT globally【8】, though its detection in LMICs may be limited by pathology constraints【17】.\u003c/p\u003e\u003cp\u003eOur survival rate of 92.9% over a median follow-up of up to 22 months is encouraging and exceeds typical LMIC survival rates (25\u0026ndash;60%)【3,15】. This figure approaches HIC outcomes, though the short follow-up period and small sample size limit interpretation. Only one patient relapsed and subsequently died, reflecting a relapse rate (7.1%) well below the 15\u0026ndash;20% commonly reported【6,8】. However, longer follow-up is necessary to capture late relapses and late treatment-related mortality.\u003c/p\u003e\u003cp\u003eOverall, our findings underscore both encouraging aspects and critical challenges in WT management in Yemen. While early-stage presentation and high short-term survival are promising, low uptake of standardized multimodal therapy, absence of radiotherapy, and limited preoperative chemotherapy use highlight systemic gaps. Addressing these requires improved diagnostic capacity, adoption of unified treatment protocols (COG or SIOP), and ensuring chemotherapy availability.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePediatric WT in Sana\u0026rsquo;a City presents predominantly in early stages with favorable histology, but access to multimodal therapy\u0026mdash;particularly radiotherapy\u0026mdash;remains limited. The high remission rate is encouraging, but long-term follow-up and resource optimization are essential to improve outcomes and align with international standards.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eWT: Wilms\u0026rsquo; tumor;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCOG: Children\u0026rsquo;s Oncology Group;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSIOP: International Society of Pediatric Oncology;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLMIC: Low- and Middle-Income Country;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHIC: High-Income Country;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOS: Overall Survival;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEFS: Event-Free Survival.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the \u003cstrong\u003eScientific Committee of the Arab Board of Urology, Sana\u0026rsquo;a, Yemen\u003c/strong\u003e (Approval Code: GMH-IRB-2024-WT-02). Written informed consent was obtained from all parents/guardians prior to enrollment. All procedures adhered to the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eParents/guardians provided written consent for anonymized data publication. No identifiable patient images or details are included.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of Data and Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDe-identified datasets are available from the corresponding author ([email protected]) upon reasonable request. Study protocols and case report forms are archived at the General Military Hospital, Sana\u0026rsquo;a.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests, financial or non-financial, related to this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received no external funding. Institutional support was provided by the \u003cstrong\u003eArab Board of Health Specialization, Sana\u0026rsquo;a\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Aziz Shamsan\u0026nbsp;\u003c/strong\u003eConceptualization, data acquisition, manuscript drafting, and final approval.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Khaled Alkohlany:\u0026nbsp;\u003c/strong\u003eStudy design, supervision, critical revision, and accountability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Majdi Alshami:\u0026nbsp;\u003c/strong\u003eSupervision, surgical management, follow-up data collection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Ahmed Farei:\u0026nbsp;\u003c/strong\u003eData collection, analysis, manuscript drafting.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Wael Alsaqaf:\u0026nbsp;\u003c/strong\u003eSurgical management, follow-up data collection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e6.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Abdullah Al-Sakkaf:\u0026nbsp;\u003c/strong\u003eImaging analysis, manuscript review.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e7. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Nasser Albaddai:\u0026nbsp;\u003c/strong\u003eStatistical analysis, manuscript review, and final approval.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the \u003cstrong\u003eArab Board of Health Specialization\u003c/strong\u003e for ethical oversight and the \u003cstrong\u003eGeneral Military Hospital (GMH), Sana\u0026rsquo;a\u003c/strong\u003e for clinical infrastructure. We acknowledge the pathology and radiology teams at GMH for diagnostic support, and nursing staff for patient care. Finally, we honor the resilience of our patients and families amid Yemen\u0026rsquo;s humanitarian crisis.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eNakata K, Colombet M, Stiller CA, Pritchard-Jones K, Steliarova-Foucher E, IICC-3 Contributors. Incidence of childhood renal tumours: An international population-based study. Int J Cancer. 2020;147(12):3313-3327.\u003c/li\u003e\n\u003cli\u003eLibes J, Hol J, Neto JCA, et al. Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges. Pediatr Blood Cancer. 2023;70(Suppl 2):e30343.\u003c/li\u003e\n\u003cli\u003eCunningham ME, Klug TD, Nuchtern JG, et al. Global disparities in Wilms tumor. J Surg Res. 2020;247:34-51.\u003c/li\u003e\n\u003cli\u003eBeckwith JB. Wilms\u0026apos; tumor and other renal tumors of childhood: A selective review from the National Wilms\u0026apos; Tumor Study Pathology Center. Hum Pathol. 1983;14(6):481-492.\u003c/li\u003e\n\u003cli\u003eGrundy PE, Breslow NE, Li S, et al. Loss of heterozygosity for chromosomes 1p and 16q is an adverse prognostic factor in favorable-histology Wilms tumor: A report from the National Wilms Tumor Study Group. J Clin Oncol. 2005;23(29):7312-7321.\u003c/li\u003e\n\u003cli\u003eGratias EJ, Dome JS, Jennings LJ, et al. Association of chromosome 1q gain with inferior survival in favorable-histology Wilms tumor: A report from the Children\u0026rsquo;s Oncology Group. J Clin Oncol. 2016;34(26):3189-3194.\u003c/li\u003e\n\u003cli\u003eChagtai T, Zill C, Dainese L, et al. Gain of 1q as a prognostic biomarker in Wilms tumors treated with preoperative chemotherapy in the International Society of Paediatric Oncology WT 2001 trial. J Clin Oncol. 2016;34(26):3195-3203.\u003c/li\u003e\n\u003cli\u003eDome JS, Graf N, Geller JI, et al. Advances in Wilms tumor treatment and biology: Progress through international collaboration. J Clin Oncol. 2015;33(27):2999-3007.\u003c/li\u003e\n\u003cli\u003evan den Heuvel-Eibrink MM, Hol JA, Pritchard-Jones K, et al. Position paper: Rationale for the treatment of Wilms tumour in the UMBRELLA SIOP-RTSG 2016 protocol. Nat Rev Urol. 2017;14(12):743-752.\u003c/li\u003e\n\u003cli\u003eFernandez CV, Mullen EA, Chi YY, et al. Outcome and prognostic factors in stage III favorable-histology Wilms tumor: A report from the Children\u0026apos;s Oncology Group study AREN0532. J Clin Oncol. 2018;36(3):254-261.\u003c/li\u003e\n\u003cli\u003eIsraels T, Moreira C, Scanlan T, et al. SIOP PODC: Recommendations for Wilms tumour in sub-Saharan Africa. Pediatr Blood Cancer. 2013;60(1):5-11.\u003c/li\u003e\n\u003cli\u003eHadley GP. The management of Wilms\u0026apos; tumour in Africa. Ann Trop Paediatr. 2011;31(2):141-151.\u003c/li\u003e\n\u003cli\u003ede Aguirre-Neto JC, de Camargo B, van Tinteren H, et al. International comparisons of clinical demographics and outcomes in the International Society of Pediatric Oncology Wilms Tumor 2001 Trial and Study. JCO Glob Oncol. 2022;8:e2100425.\u003c/li\u003e\n\u003cli\u003eVujanić GM, Parsons LN, D\u0026apos;Hooghe E, Treece AL, Collini P, Perlman EJ. Pathology of Wilms\u0026apos; tumour in International Society of Paediatric Oncology (SIOP) and Children\u0026apos;s oncology group (COG) renal tumour studies: similarities and differences. Histopathology. 2022 Jun;80(7):1026-37. \u003c/li\u003e\n\u003cli\u003eEkenze SO, Okafor OC, Obasi AA, et al. Wilms tumor in Africa: A systematic review of management challenges and outcome in two decades. Pediatr Blood Cancer. 2020;67(9):e28695.\u003c/li\u003e\n\u003cli\u003eBreslow NE, Olshan A, Beckwith JB, Green DM. Epidemiology of Wilms tumor. Med Pediatr Oncol. 1993;21(3):172-181.\u003c/li\u003e\n\u003cli\u003eElhassan MM, Suliman SO, Awooda HA, et al. Management and outcome of Wilms\u0026apos; tumor in Sudan: Challenges and future prospects. Afr J Paediatr Surg. 2021;18(1):1-6.\u003c/li\u003e\n\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":"Wilms’ tumor, nephroblastoma, Yemen, pediatric oncology, COG staging, survival outcomes","lastPublishedDoi":"10.21203/rs.3.rs-7334363/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7334363/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWilms’ tumor (WT) is the most common pediatric renal malignancy, accounting for approximately 90% of kidney tumors in children. While outcomes in high-income countries exceed 90% survival, data from low-resource settings remain scarce, and no published series from Yemen exist.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo describe the demographic distribution, clinical presentation, management patterns, and short-term outcomes of pediatric WT cases in Sana’a City, Yemen.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis prospective study included all children aged ≤15 years with histologically confirmed WT, managed across governmental and private hospitals in Sana’a between January 2021 and December 2022. Demographic, clinical, radiological, surgical, and histopathological data were collected using a standardized case report form. Tumors were staged according to the Children’s Oncology Group (COG) criteria. Treatment modalities and outcomes, including event-free survival and overall survival at two years.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFourteen patients were identified, with a male predominance (71.4%) and mean age 3.6 ± 3.5 years. Abdominal mass was the most common presentation (85.7%). Right-sided tumors predominated (64.3%), and all lesions were solid. According to COG staging, 35.7% were Stage I, 50.0% Stage II, and 14.3% Stage III; all had favorable histology. Preoperative chemotherapy was administered in 28.6% of patients, all underwent surgical resection, and 21.4% received postoperative chemotherapy. No patient received radiotherapy. At a median follow-up of 15 months (range: 7–22), 92.9% achieved complete remission, and one patient (7.1%) relapsed and died 18 months postoperatively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePediatric WT in Sana’a City presents predominantly in early stages with favorable histology, but access to multimodal therapy—particularly radiotherapy—remains limited. The high remission rate is encouraging, but long-term follow-up and resource optimization are essential to improve outcomes and align with international standards.\u003c/p\u003e","manuscriptTitle":"Wilms' Tumor: Distribution, Demographics, and Outcomes in Sanaa City","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 14:26:51","doi":"10.21203/rs.3.rs-7334363/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":"4cb8b688-39a3-47c5-b68a-4bd95058a26d","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-22T08:57:50+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 14:26:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7334363","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7334363","identity":"rs-7334363","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}