Gas Production Characteristics of Small Intestinal Bacteria in Patients with Colorectal Cancers: A Study Using the Lactulose Breath Test

Gas Production Characteristics of Small Intestinal Bacteria in Patients with Colorectal Cancers: A Study Using the Lactulose Breath Test | 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 Gas Production Characteristics of Small Intestinal Bacteria in Patients with Colorectal Cancers: A Study Using the Lactulose Breath Test Wei-Ran Chen, Dong-Xia Hu, Xiao-Feng Liang, Hao-Jie Zhong, Xing-Xiang He This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4791552/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 Colorectal cancers (CRC) have been suggested to be involved with coliform bacteria, while the association with small intestinal bacteria is not clear. The study objective was to investigate the relationship between patients with CRC and the gas production characteristics of small intestinal bacteria using the lactulose breath test (LBT). Methods Data on age, gender, body mass index (BMI), hydrogen and methane concentrations at various time points, and colonoscopy results of patients with bowel diseases were collected from 2017 through 2023. The gas production characteristics of small intestinal bacteria were analyzed in patients with functional and organic bowel diseases, particularly in those patients with polyps and CRC. Additionally, receiver operating characteristic (ROC) analysis was performed to differentiate between these conditions. Results A total of 274 patients with functional bowel diseases, 274 patients with organic bowel diseases, 214 patients with polyps, and 18 patients with CRC were included. Methane concentrations in patients with organic bowel diseases, whether polyps or CRC, were significantly higher than in those with functional bowel diseases. Conversely, hydrogen concentrations were significantly higher in patients with functional bowel diseases compared to those with organic bowel diseases and polyps at certain time points. The area under the curve (AUC) for the methane concentrations at the 60-minute mark in predicting CRC was 0.7104 (95% confidence interval, 0.6166–0.8042). Among patients with CRC, hydrogen concentrations were significantly higher in those with CRC compared to those with polyps. Conclusions There were distinct features of hydrogen and methane production in patients with organic bowel diseases compared to those with functional bowel diseases. Patients with CRC or polyps exhibited higher methane concentrations. Additionally, the LBT appears to be a promising tool for distinguishing functional bowel diseases and CRC. colorectal cancer (CRC) polyp small intestinal bacterial overgrowth (SIBO) breath test microbiota hydrogen methane Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Background Colorectal polyps are a common condition affecting people worldwide, with a prevalence of 26.4% in patients under 50 years old [ 1 ] and over 50% in patients over 60 years old. [ 2 ] These polyps can deteriorate and develop into colorectal cancer (CRC), [ 3 ] which is the second-most common cause of cancer-related mortality. [ 4 ] However, the factors influencing the progression of polyps into CRC are not yet well defined. Small intestinal bacterial overgrowth (SIBO) is defined as an excess of bacteria in the small intestine, [ 5 ] particularly those producing hydrogen and methane. It can be effectively diagnosed through the lactulose breath test (LBT), [ 6 ] which reflects the gas production characteristics of small intestinal bacteria. SIBO has been implicated in various diseases, such as irritable bowel syndrome, [ 7 , 8 ] ulcerative colitis, [ 9 ] and Crohn's disease. [ 9 , 10 ] Additionally, recent animal experiments have found that the intestinal microbiota can promote the occurrence and deterioration of polyps and CRC. [ 11 ] However, the relationship between CRC and SIBO remains poorly characterized. Therefore, our study was designed to examine the relationship between CRC and the gas production characteristics of small intestinal bacteria using the LBT. Methods Study Design All patients who underwent the LBT and colonoscopy were recruited for this retrospective study at the First Affiliated Hospital of Guangdong Pharmaceutical University between September 2017 and May 2023. The exclusion criteria included recent antibiotic usage within the past month or age under 18 years. Patients were categorized into the functional bowel disease group if they presented symptoms such as abdominal pain, abdominal distension, or changes in stool frequency or form, [ 12 ] and their colonoscopy results showed no organic pathology. Conversely, patients were classified into the organic bowel disease group if organic pathology was detected during colonoscopy. Within the organic bowel disease group, patients were further subdivided into the intestinal cancer group if they had a previous diagnosis of intestinal cancer and into the polyp group if they had polyps without intestinal cancer. Data Collection The data required for this study primarily encompassed age, gender, body mass index (BMI), hydrogen and methane concentrations at various time points, and colonoscopy results including details on intestinal disease and the number and size of polyps. LBT Patients were instructed to fast for at least 12 hours before the test. Following the initial breath collection, they consumed a sugar mixture comprising 10 g of lactulose dissolved in 50 ml of warm water. Subsequent breath samples were collected every 30 minutes for 2.5 hours and analyzed using the Quintron Breath Tracker (SC model). [ 13 ] Statistical Analysis Data analyses and graphical representations were generated using Prism 9 (GraphPad, San Diego, CA, USA). Qualitative variables were presented as a frequency distribution. Normally distributed variables were reported as means and standard deviations, while non-normally distributed variables were described as medians and interquartile ranges. Continuous variable comparisons were conducted using t-tests for normally distributed variables and non-parametric Wilcoxon rank sum tests for non-normally distributed variables. Receiver operating characteristic (ROC) curves and areas under the curves (AUC) were used to assess LBT data for distinguishing between different types of intestinal diseases. Statistical significance was assumed for P values less than 0.05. Results Demographics and clinical characteristics of patients Based on our criteria, a total of 548 patients were included in the study, including 274 patients with functional bowel disease and 274 patients with organic bowel disease. Both groups were matched by gender, with 141 (51.5%) males in each group. These differences were not statistically significant between the patients with functional and organic bowel disease in terms of age (median: 56.0 years [interquartile range, IQR, 44.0–64.0 years] vs. 57.0 years [IQR, 49.0–65.0 years], P = 0.067) or BMI (median: 22.5 kg/m 2 [IQR, 20.3–25.2 kg/m 2 ] vs. 23.2 kg/m 2 [IQR, 20.8–25.8 kg/m 2 ], P = 0.068). Comparison of hydrogen and methane concentrations between patients with functional and organic bowel disease Compared to organic bowel patients, functional bowel patients' hydrogen concentrations were significantly higher at the 0-, 120-, and 150-minute time points (P < 0.05). Conversely, patients with organic bowel disease had higher methane concentrations than those with functional bowel disease at all time points (P < 0.05; Fig. 1 ). Comparison of hydrogen and methane concentrations between patients with functional bowel disease and colorectal polyps A total of 214 patients with colorectal polyp were included. The functional bowel disease group had significantly higher hydrogen concentrations than the colorectal polyp group at all time points except for the 30-minute mark (P < 0.05). Conversely, the functional bowel disease group had significantly lower methane concentrations compared to the colorectal polyp group at all time points (P < 0.05; Fig. 2 ). Comparison of hydrogen and methane concentrations between patients with functional bowel disease and CRC There were 18 patients with intestinal CRC in this study. The difference in hydrogen concentrations between the two groups was not statistically significant (P > 0.05). However, patients with CRC had significantly higher methane concentrations than those with functional bowel disease at all time points except for the 150-minute mark (P < 0.05; Fig. 3 ). Comparison of hydrogen and methane concentrations between patients with colorectal polyps and CRC Hydrogen concentrations were significantly higher in patients with CRC compared to those with colorectal polyp at the 60-, 90-, 120-, and 150-minute time points (P 0.05; Fig. 4 ). Comparison of hydrogen and methane concentrations between patients with single and multiple polyps Based on the number of polyps, the 214 patients in the colorectal polyp group were divided into two groups: 87 patients with a single polyp and 127 patients with multiple polyps. Although there were no between-group differences in hydrogen concentrations (P > 0.05), the methane concentrations in the multiple polyp group were significantly higher at the 0-, 30-, 60-, and 120-minute time points compared to the single polyp group (P < 0.05; Fig. 5 ). Comparison of hydrogen and methane concentrations between patients with small and large polyps Based on the size of the polyps, the 214 patients with colorectal polyps were classified into two groups: 184 patients with small polyps (≤ 1 cm) and 30 patients with large polyps (> 1 cm). Differences between the two groups were not statistically significant in hydrogen and methane concentrations (P > 0.05; Fig. 6 ). ROC curve for predicting To determine the efficacy of LBT as a potential marker for cancer, we generated a ROC curve. We found that the methane concentration at the 60-minute time point discriminates between functional bowel disease and the cancer groups. The AUC was 0.7104 (95% confidence interval: 0.6166–0.8042; Fig. 7 ). Discussion Our study showed that patients with functional bowel disease had significantly increased hydrogen concentrations and significantly decreased methane concentrations compared to those with organic bowel disease. A significant difference was observed in the hydrogen concentrations between patients with CRC and those with colorectal polyps. Additionally, the methane concentrations were significantly higher in patients with multiple polyps compared to those with a single polyp. Numerous studies demonstrate that gut microbiota, particularly coliform bacteria, are related to functional bowel disease. [ 14 ] A study in southwest China found that the richness of gut microbiota in irritable bowel syndrome was significantly lower than in healthy controls, as determined by 16S rRNA sequencing. [ 15 ] Moreover, species diversity in the fecal microbiome of patients with inflammatory bowel disease was significantly depleted. [ 16 ] However, only a small number of studies suggest an association between small intestine microflora and functional bowel disease. In this study, we demonstrate that patients with functional bowel disease had increased hydrogen concentrations in the LBT compared to those with organic bowel disease. Similarly, Henry et al. found that patients with irritable bowel syndrome had significantly higher total hydrogen production compared to healthy controls. [ 17 ] However, another study showed no difference in hydrogen concentrations in the LBT between patients with irritable bowel syndrome and healthy controls, [ 18 ] possibly due to different inclusion criteria for control groups among these studies. Significantly reduced methane concentrations were observed in patients with functional bowel disease, despite their increased hydrogen concentrations. Consistent with this finding, Rana et al. found that patients with irritable bowel syndrome presented lower methane concentrations along with higher hydrogen concentrations. [ 19 ] Our findings indicate that the LBT could be used to distinguish between functional and organic bowel diseases and that hydrogen and methane concentrations could be involved in the development of intestinal diseases. The relationship between polyps (both benign and malignant) and the gut microbiota has been explored in various studies. Notably, a recent study indicates that the gut microbiota in patients with CRC exhibits higher species richness and a greater abundance of procarcinogenic taxa compared to healthy individuals. [ 20 ] Similar patterns have been observed in patients with polyps. [ 21 ] Furthermore, the gut microbiota is suggested to contribute to the development of polyps and CRC. In mouse gavage experiments, fecal microbiota from patients with CRC led to an increase in the number of polyps and promoted intestinal carcinogenesis. [ 11 ] Mechanistically, gut microbiota may facilitate the development of CRC by inducing inflammation, compromising the epithelial barrier, stimulating cellular proliferation, disrupting gut microbiome homeostasis, [ 22 ] and altering metabolism. [ 23 ] However, there are very few studies examining the relationship between the microflora of the small intestine and polyps (whether benign or malignant). In this study, we observed that patients with polyps or CRC had elevated methane concentrations. Increased methane in the small intestine can reduce intestinal peristalsis, slowing down the intestinal transport rate, which is a major trigger for constipation. [ 24 , 25 ] Mechanistically, constipation may increase the contact time between the colonic mucosa and potential carcinogens in the stool, subsequently promoting the development of polyps and CRC. [ 26 ] Moreover, we found significant differences in methane concentrations at the 60-minute mark between patients with functional bowel disease and those with CRC. The AUC for this marker was 0.7104 (95% confidence interval, 0.6166–0.8042), suggesting that this measurement could potentially distinguish between functional bowel disease and CRC. In subgroup analyses, patients with multiple polyps exhibited higher methane concentrations compared to those with a single polyp. However, no significant difference was observed based on the size of the polyp. Consequently, the LBT emerges as a promising tool for distinguishing between patients with single and multiple polyps. Further investigation is required to establish whether there is a causal connection between methane concentrations and the number of polyps. The main limitation of our study lies in the small patient population within the CRC group. Consequently, patients were enrolled in the CRC group regardless of whether they had undergone surgery or not. As this was a retrospective study, clinical data regarding the treatment history and surgical interventions of patients with CRC were not collected. These limitations may have introduced potential inaccuracies into our findings. Therefore, it is imperative to expand the sample size and conduct subgroup analyses to validate our results. Conclusions In summary, our study revealed distinct hydrogen and methane profiles in patients with organic bowel diseases compared to those with functional disorders. Specifically, patients with polyps or CRC demonstrated elevated methane concentrations. Furthermore, the LBT emerged as an effective tool for distinguishing between functional bowel diseases and CRC. List Of Abbreviations CRC, colorectal cancers LBT, lactulose breath test SIBO, small intestinal bacterial overgrowth BMI, body mass index ROC, receiver operating characteristic AUC, area under curve CI, confidence interval. Declarations Ethics approval Ethics approval was granted by the Ethics Review Committee of the First Affiliated Hospital of Guangdong Pharmaceutical University (approval no. 2019045). All participants provided written, informed consent. Availability of data and materials The data that support the findings of this study are available from the corresponding author (Xing-Xiang He) upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding This work was supported by the Guangdong Provincial Department of Science and Technology (No. 2022B1111070006), the Education Department of Guangdong Province (No. 2021KCXTD025), the Health Commission of Guangdong Province (No. B2022209), and the Traditional Chinese Medicine Bureau of Guangdong Province (No. 20221232). Authors' contributions W.C. contributed to analyzing the data and writing the article; D.H. and X.L. contributed to collecting the data; X.H. and H.Z. contributed to the design of the experiments and the revision of the paper. All authors reviewed the manuscript. Acknowledgements Not applicable. References LIANG PS, WILLIAMS J L, DOMINITZ JA et al. Age-Stratified Prevalence and Predictors of Neoplasia Among U.S. Adults Undergoing Screening Colonoscopy in a National Endoscopy Registry [J]. Gastroenterology, 2022, 163(3). LIU J, YANG S, WANG Z, et al. 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Intestinal bacteria and colorectal cancer: etiology and treatment [J]. Gut Microbes. 2023;15(1):2185028. PARTHASARATHY G, CHEN J, CHEN X et al. Relationship Between Microbiota of the Colonic Mucosa vs Feces and Symptoms, Colonic Transit, and Methane Production in Female Patients With Chronic Constipation [J]. Gastroenterology, 2016, 150(2). PIMENTEL M, LIN H C, ENAYATI P, et al. Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity [J]. Am J Physiol Gastrointest Liver Physiol. 2006;290(6):G1089–95. STALLER K, OLéN O, SöDERLING J et al. Chronic Constipation as a Risk Factor for Colorectal Cancer: Results From a Nationwide, Case-Control Study [J]. Clin Gastroenterol Hepatology: Official Clin Pract J Am Gastroenterological Association, 2022, 20(8). Additional Declarations No competing interests reported. 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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-4791552","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":343393429,"identity":"7bcd73b0-473c-49b6-b4a9-999446c0582f","order_by":0,"name":"Wei-Ran Chen","email":"","orcid":"","institution":"The First Affiliated Hospital of Guangdong Pharmaceutical University","correspondingAuthor":false,"prefix":"","firstName":"Wei-Ran","middleName":"","lastName":"Chen","suffix":""},{"id":343393430,"identity":"310ad1e9-2dd4-4f5b-b5a6-a42ce220ec30","order_by":1,"name":"Dong-Xia Hu","email":"","orcid":"","institution":"The First Affiliated Hospital of Guangdong Pharmaceutical University","correspondingAuthor":false,"prefix":"","firstName":"Dong-Xia","middleName":"","lastName":"Hu","suffix":""},{"id":343393431,"identity":"6022c648-bfdc-434a-ba61-828e5c59e07f","order_by":2,"name":"Xiao-Feng Liang","email":"","orcid":"","institution":"The First Affiliated Hospital of Guangdong Pharmaceutical University","correspondingAuthor":false,"prefix":"","firstName":"Xiao-Feng","middleName":"","lastName":"Liang","suffix":""},{"id":343393432,"identity":"f693d4ef-53f0-48d8-b3b6-e4b5a35e6107","order_by":3,"name":"Hao-Jie Zhong","email":"","orcid":"","institution":"The First Affiliated Hospital of Guangdong Pharmaceutical University","correspondingAuthor":false,"prefix":"","firstName":"Hao-Jie","middleName":"","lastName":"Zhong","suffix":""},{"id":343393433,"identity":"7dbdfff6-fa34-4b8b-a472-a5baaa9cfbf9","order_by":4,"name":"Xing-Xiang He","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBElEQVRIiWNgGAWjYBACAyA+AMQ8QMz4gIENLkicFmYDorXAAJsEUVrM2XsMDxf8OizDP7v9WuWXsjuJDezN2yQYau7g1GLZcyzh8My+NB6JO2fKbsuce5bYwHOsTILh2DPcDruRfOAwb48ND8ONnLTbkm2HExskcswkGBsO49Zy/2EDUIsEjzxQSzFYi/wbAlpuMB84zPPDhsfgRvoxxo9gW3gIaDmTlnCYtyGNx/BGDrM0w7lnxm08acUWCcfwaDl+xvgzz5/D9nI30h9+/FF2R7af/fDGGx9qcGsBA8Y2EMljwMwDjFZw1CTg1wAEf0AE+wPGH+CUMApGwSgYBaMAFQAAGBBdwl+vt9YAAAAASUVORK5CYII=","orcid":"","institution":"The First Affiliated Hospital of Guangdong Pharmaceutical University","correspondingAuthor":true,"prefix":"","firstName":"Xing-Xiang","middleName":"","lastName":"He","suffix":""}],"badges":[],"createdAt":"2024-07-24 01:08:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4791552/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4791552/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":63801052,"identity":"355c186a-04d5-4733-a2fb-575ee212cc65","added_by":"auto","created_at":"2024-09-02 13:14:10","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":64447,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with functional bowel disease (n = 274) and organic bowel disease (n = 274). Error bars denote SEM. SEM, standard error mean; LBT, lactulose breath test; Ppm, parts per million. * \u0026lt;0.05, **\u0026lt;0.01.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/38a7221bb9259cee0f7f429b.png"},{"id":63801054,"identity":"d5100751-1f7b-43b8-ae93-d7c3589558d0","added_by":"auto","created_at":"2024-09-02 13:14:10","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":61161,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with functional bowel disease (n=274) and colorectal polyp (n=214). Error bars denote SEM. SEM, standard error mean; LBT, lactulose breath test; Ppm, parts per million. *\u0026lt;0.05, **\u0026lt;0.01.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/a7cf84a1f96286c5ef113c39.png"},{"id":63803100,"identity":"9dfbfc96-65f2-4c4e-a3c7-591e8f0a3122","added_by":"auto","created_at":"2024-09-02 13:22:10","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":59306,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with functional bowel disease (n = 274) and colorectal cancer (n = 18). Error bars denote SEM.\u003c/p\u003e\n\u003cp\u003eSEM, standard error mean; LBT, lactulose breath test; Ppm, parts per million. *\u0026lt;0.05, **\u0026lt;0.01.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/e0eff97390c41b143eb715c4.png"},{"id":63801058,"identity":"72ade9e1-4c95-4fdb-be94-464f18af7ee1","added_by":"auto","created_at":"2024-09-02 13:14:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":55792,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with colorectal polyps (n = 214) and CRC (n = 18). Error bars denote SEM.\u003c/p\u003e\n\u003cp\u003eSEM, standard error mean; LBT, lactulose breath test; CRC, colorectal cancer; Ppm, parts per million. *\u0026lt;0.05.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/4237550bdd59da1dc6369658.png"},{"id":63801055,"identity":"933da729-50ac-4202-86b1-134e5de72ff2","added_by":"auto","created_at":"2024-09-02 13:14:11","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":58323,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with a single polyp (n = 87) and multiple polyps (n = 127). Error bars denote SEM.\u003c/p\u003e\n\u003cp\u003eSEM, standard error mean; LBT, lactulose breath test; Ppm, parts per million. *\u0026lt;0.05, **\u0026lt;0.01.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/c800b74f07b2f2fb19b9f039.png"},{"id":63801056,"identity":"3de10b4a-b6f1-40eb-b54c-be00997ccaef","added_by":"auto","created_at":"2024-09-02 13:14:11","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":57586,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of hydrogen and methane concentrations in the LBT between patients with polyp size ≤1 cm (n = 184) and polyp size \u0026gt;1 cm (n = 30). Error bars denote SEM.\u003c/p\u003e\n\u003cp\u003eSEM, standard error mean; LBT, lactulose breath test; Ppm, parts per million.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/32c9100cdb9ef3d3279ec50f.png"},{"id":63801057,"identity":"9686eedf-1b69-484c-a74a-d8ebead8f756","added_by":"auto","created_at":"2024-09-02 13:14:11","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":86348,"visible":true,"origin":"","legend":"\u003cp\u003eROC curve for the methane concentration at the 60-minute time point, differentiating between the functional bowel disease and cancer groups.\u003c/p\u003e\n\u003cp\u003eROC, receiver operating characteristic; AUC, area under curve; CI, confidence interval.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/edd9fc509af33d7d1310c4c9.png"},{"id":90967070,"identity":"28d35703-10ea-4f96-ba4d-3d0872be0219","added_by":"auto","created_at":"2025-09-10 06:47:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1174386,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4791552/v1/f2ada1e3-251e-48d5-9eec-a471b690c1d5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Gas Production Characteristics of Small Intestinal Bacteria in Patients with Colorectal Cancers: A Study Using the Lactulose Breath Test","fulltext":[{"header":"Background","content":"\u003cp\u003eColorectal polyps are a common condition affecting people worldwide, with a prevalence of 26.4% in patients under 50 years old\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e and over 50% in patients over 60 years old.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e These polyps can deteriorate and develop into colorectal cancer (CRC),\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e which is the second-most common cause of cancer-related mortality.\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e However, the factors influencing the progression of polyps into CRC are not yet well defined.\u003c/p\u003e \u003cp\u003eSmall intestinal bacterial overgrowth (SIBO) is defined as an excess of bacteria in the small intestine,\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e particularly those producing hydrogen and methane. It can be effectively diagnosed through the lactulose breath test (LBT),\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e which reflects the gas production characteristics of small intestinal bacteria. SIBO has been implicated in various diseases, such as irritable bowel syndrome,\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e ulcerative colitis,\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e and Crohn's disease.\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e Additionally, recent animal experiments have found that the intestinal microbiota can promote the occurrence and deterioration of polyps and CRC.\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e However, the relationship between CRC and SIBO remains poorly characterized.\u003c/p\u003e \u003cp\u003eTherefore, our study was designed to examine the relationship between CRC and the gas production characteristics of small intestinal bacteria using the LBT.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design\u003c/h2\u003e \u003cp\u003eAll patients who underwent the LBT and colonoscopy were recruited for this retrospective study at the First Affiliated Hospital of Guangdong Pharmaceutical University between September 2017 and May 2023. The exclusion criteria included recent antibiotic usage within the past month or age under 18 years. Patients were categorized into the functional bowel disease group if they presented symptoms such as abdominal pain, abdominal distension, or changes in stool frequency or form,\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e and their colonoscopy results showed no organic pathology. Conversely, patients were classified into the organic bowel disease group if organic pathology was detected during colonoscopy. Within the organic bowel disease group, patients were further subdivided into the intestinal cancer group if they had a previous diagnosis of intestinal cancer and into the polyp group if they had polyps without intestinal cancer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eData Collection\u003c/h2\u003e \u003cp\u003eThe data required for this study primarily encompassed age, gender, body mass index (BMI), hydrogen and methane concentrations at various time points, and colonoscopy results including details on intestinal disease and the number and size of polyps.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eLBT\u003c/h2\u003e \u003cp\u003ePatients were instructed to fast for at least 12 hours before the test. Following the initial breath collection, they consumed a sugar mixture comprising 10 g of lactulose dissolved in 50 ml of warm water. Subsequent breath samples were collected every 30 minutes for 2.5 hours and analyzed using the Quintron Breath Tracker (SC model).\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eData analyses and graphical representations were generated using Prism 9 (GraphPad, San Diego, CA, USA). Qualitative variables were presented as a frequency distribution. Normally distributed variables were reported as means and standard deviations, while non-normally distributed variables were described as medians and interquartile ranges. Continuous variable comparisons were conducted using t-tests for normally distributed variables and non-parametric Wilcoxon rank sum tests for non-normally distributed variables. Receiver operating characteristic (ROC) curves and areas under the curves (AUC) were used to assess LBT data for distinguishing between different types of intestinal diseases. Statistical significance was assumed for P values less than 0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eDemographics and clinical characteristics of patients\u003c/h2\u003e\n \u003cp\u003eBased on our criteria, a total of 548 patients were included in the study, including 274 patients with functional bowel disease and 274 patients with organic bowel disease. Both groups were matched by gender, with 141 (51.5%) males in each group. These differences were not statistically significant between the patients with functional and organic bowel disease in terms of age (median: 56.0 years [interquartile range, IQR, 44.0\u0026ndash;64.0 years] vs. 57.0 years [IQR, 49.0\u0026ndash;65.0 years], P\u0026thinsp;=\u0026thinsp;0.067) or BMI (median: 22.5 kg/m\u003csup\u003e2\u003c/sup\u003e [IQR, 20.3\u0026ndash;25.2 kg/m\u003csup\u003e2\u003c/sup\u003e] vs. 23.2 kg/m\u003csup\u003e2\u003c/sup\u003e [IQR, 20.8\u0026ndash;25.8 kg/m\u003csup\u003e2\u003c/sup\u003e], P\u0026thinsp;=\u0026thinsp;0.068).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with functional and organic bowel disease\u003c/h2\u003e\n \u003cp\u003eCompared to organic bowel patients, functional bowel patients\u0026apos; hydrogen concentrations were significantly higher at the 0-, 120-, and 150-minute time points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Conversely, patients with organic bowel disease had higher methane concentrations than those with functional bowel disease at all time points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with functional bowel disease and colorectal polyps\u003c/h2\u003e\n \u003cp\u003eA total of 214 patients with colorectal polyp were included. The functional bowel disease group had significantly higher hydrogen concentrations than the colorectal polyp group at all time points except for the 30-minute mark (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Conversely, the functional bowel disease group had significantly lower methane concentrations compared to the colorectal polyp group at all time points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with functional bowel disease and CRC\u003c/h2\u003e\n \u003cp\u003eThere were 18 patients with intestinal CRC in this study. The difference in hydrogen concentrations between the two groups was not statistically significant (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, patients with CRC had significantly higher methane concentrations than those with functional bowel disease at all time points except for the 150-minute mark (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with colorectal polyps and CRC\u003c/h2\u003e\n \u003cp\u003eHydrogen concentrations were significantly higher in patients with CRC compared to those with colorectal polyp at the 60-, 90-, 120-, and 150-minute time points (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No significant differences in methane concentrations were observed among the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with single and multiple polyps\u003c/h2\u003e\n \u003cp\u003eBased on the number of polyps, the 214 patients in the colorectal polyp group were divided into two groups: 87 patients with a single polyp and 127 patients with multiple polyps. Although there were no between-group differences in hydrogen concentrations (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), the methane concentrations in the multiple polyp group were significantly higher at the 0-, 30-, 60-, and 120-minute time points compared to the single polyp group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003eComparison of hydrogen and methane concentrations between patients with small and large polyps\u003c/h2\u003e\n \u003cp\u003eBased on the size of the polyps, the 214 patients with colorectal polyps were classified into two groups: 184 patients with small polyps (\u0026le;\u0026thinsp;1 cm) and 30 patients with large polyps (\u0026gt;\u0026thinsp;1 cm). Differences between the two groups were not statistically significant in hydrogen and methane concentrations (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05; Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003ch2\u003eROC curve for predicting\u003c/h2\u003e\n \u003cp\u003eTo determine the efficacy of LBT as a potential marker for cancer, we generated a ROC curve. We found that the methane concentration at the 60-minute time point discriminates between functional bowel disease and the cancer groups. The AUC was 0.7104 (95% confidence interval: 0.6166\u0026ndash;0.8042; Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur study showed that patients with functional bowel disease had significantly increased hydrogen concentrations and significantly decreased methane concentrations compared to those with organic bowel disease. A significant difference was observed in the hydrogen concentrations between patients with CRC and those with colorectal polyps. Additionally, the methane concentrations were significantly higher in patients with multiple polyps compared to those with a single polyp.\u003c/p\u003e \u003cp\u003eNumerous studies demonstrate that gut microbiota, particularly coliform bacteria, are related to functional bowel disease.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e A study in southwest China found that the richness of gut microbiota in irritable bowel syndrome was significantly lower than in healthy controls, as determined by 16S rRNA sequencing.\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e Moreover, species diversity in the fecal microbiome of patients with inflammatory bowel disease was significantly depleted.\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e However, only a small number of studies suggest an association between small intestine microflora and functional bowel disease. In this study, we demonstrate that patients with functional bowel disease had increased hydrogen concentrations in the LBT compared to those with organic bowel disease. Similarly, Henry et al. found that patients with irritable bowel syndrome had significantly higher total hydrogen production compared to healthy controls.\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e However, another study showed no difference in hydrogen concentrations in the LBT between patients with irritable bowel syndrome and healthy controls,\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e possibly due to different inclusion criteria for control groups among these studies.\u003c/p\u003e \u003cp\u003eSignificantly reduced methane concentrations were observed in patients with functional bowel disease, despite their increased hydrogen concentrations. Consistent with this finding, Rana et al. found that patients with irritable bowel syndrome presented lower methane concentrations along with higher hydrogen concentrations.\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e Our findings indicate that the LBT could be used to distinguish between functional and organic bowel diseases and that hydrogen and methane concentrations could be involved in the development of intestinal diseases.\u003c/p\u003e \u003cp\u003eThe relationship between polyps (both benign and malignant) and the gut microbiota has been explored in various studies. Notably, a recent study indicates that the gut microbiota in patients with CRC exhibits higher species richness and a greater abundance of procarcinogenic taxa compared to healthy individuals.\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e Similar patterns have been observed in patients with polyps.\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e Furthermore, the gut microbiota is suggested to contribute to the development of polyps and CRC. In mouse gavage experiments, fecal microbiota from patients with CRC led to an increase in the number of polyps and promoted intestinal carcinogenesis.\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e Mechanistically, gut microbiota may facilitate the development of CRC by inducing inflammation, compromising the epithelial barrier, stimulating cellular proliferation, disrupting gut microbiome homeostasis,\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e and altering metabolism.\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e However, there are very few studies examining the relationship between the microflora of the small intestine and polyps (whether benign or malignant).\u003c/p\u003e \u003cp\u003eIn this study, we observed that patients with polyps or CRC had elevated methane concentrations. Increased methane in the small intestine can reduce intestinal peristalsis, slowing down the intestinal transport rate, which is a major trigger for constipation.\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e Mechanistically, constipation may increase the contact time between the colonic mucosa and potential carcinogens in the stool, subsequently promoting the development of polyps and CRC.\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e Moreover, we found significant differences in methane concentrations at the 60-minute mark between patients with functional bowel disease and those with CRC. The AUC for this marker was 0.7104 (95% confidence interval, 0.6166\u0026ndash;0.8042), suggesting that this measurement could potentially distinguish between functional bowel disease and CRC.\u003c/p\u003e \u003cp\u003eIn subgroup analyses, patients with multiple polyps exhibited higher methane concentrations compared to those with a single polyp. However, no significant difference was observed based on the size of the polyp. Consequently, the LBT emerges as a promising tool for distinguishing between patients with single and multiple polyps. Further investigation is required to establish whether there is a causal connection between methane concentrations and the number of polyps.\u003c/p\u003e \u003cp\u003eThe main limitation of our study lies in the small patient population within the CRC group. Consequently, patients were enrolled in the CRC group regardless of whether they had undergone surgery or not. As this was a retrospective study, clinical data regarding the treatment history and surgical interventions of patients with CRC were not collected. These limitations may have introduced potential inaccuracies into our findings. Therefore, it is imperative to expand the sample size and conduct subgroup analyses to validate our results.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, our study revealed distinct hydrogen and methane profiles in patients with organic bowel diseases compared to those with functional disorders. Specifically, patients with polyps or CRC demonstrated elevated methane concentrations. Furthermore, the LBT emerged as an effective tool for distinguishing between functional bowel diseases and CRC.\u003c/p\u003e"},{"header":"List Of Abbreviations","content":"\u003cp\u003eCRC, colorectal cancers\u003c/p\u003e \u003cp\u003eLBT, lactulose breath test\u003c/p\u003e \u003cp\u003eSIBO, small intestinal bacterial overgrowth\u003c/p\u003e \u003cp\u003eBMI, body mass index\u003c/p\u003e \u003cp\u003eROC, receiver operating characteristic\u003c/p\u003e \u003cp\u003eAUC, area under curve\u003c/p\u003e \u003cp\u003eCI, confidence interval.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval was granted by the Ethics Review Committee of the First Affiliated Hospital of Guangdong Pharmaceutical University (approval no. 2019045). All participants provided written, informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author (Xing-Xiang He) upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Guangdong Provincial Department of Science and Technology (No. 2022B1111070006), the Education Department of Guangdong Province (No. 2021KCXTD025), the Health Commission of Guangdong Province (No. B2022209), and the Traditional Chinese Medicine Bureau of Guangdong Province (No. 20221232).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eW.C. contributed to analyzing the data and writing the article; D.H. and X.L. contributed to collecting the data; X.H. and H.Z. contributed to the design of the experiments and the revision of the paper. All authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLIANG PS, WILLIAMS J L, DOMINITZ JA et al. Age-Stratified Prevalence and Predictors of Neoplasia Among U.S. Adults Undergoing Screening Colonoscopy in a National Endoscopy Registry [J]. Gastroenterology, 2022, 163(3).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLIU J, YANG S, WANG Z, et al. Ubiquitin ligase A20 regulates p53 protein in human colon epithelial cells [J]. J Biomed Sci. 2013;20(1):74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBOND JH. Polyp guideline: diagnosis, treatment, and surveillance for patients with nonfamilial colorectal polyps. The Practice Parameters Committee of the American College of Gastroenterology [J]. 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Small Intestinal Bacterial Overgrowth in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Case-Control Studies [J]. Am J Gastroenterol. 2020;115(2):190\u0026ndash;201.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGANDHI A, SHAH A, JONES M P, et al. Methane positive small intestinal bacterial overgrowth in inflammatory bowel disease and irritable bowel syndrome: A systematic review and meta-analysis [J]. Gut Microbes. 2021;13(1):1933313.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSHAH A, MORRISON M. BURGER D, et al. Systematic review with meta-analysis: the prevalence of small intestinal bacterial overgrowth in inflammatory bowel disease [J]. Volume 49. Alimentary Pharmacology \u0026amp; Therapeutics; 2019. pp. 624\u0026ndash;35. 6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRUTGEERTS P, GHOOS Y, VANTRAPPEN G, et al. Ileal dysfunction and bacterial overgrowth in patients with Crohn's disease [J]. 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J R, Microbiome and colorectal cancer: Roles in carcinogenesis and clinical potential [J]. Mol Aspects Med, 2019, 69.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDOUGHERTY M W JOBINC. Intestinal bacteria and colorectal cancer: etiology and treatment [J]. Gut Microbes. 2023;15(1):2185028.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePARTHASARATHY G, CHEN J, CHEN X et al. Relationship Between Microbiota of the Colonic Mucosa vs Feces and Symptoms, Colonic Transit, and Methane Production in Female Patients With Chronic Constipation [J]. Gastroenterology, 2016, 150(2).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePIMENTEL M, LIN H C, ENAYATI P, et al. Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity [J]. 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Clin Gastroenterol Hepatology: Official Clin Pract J Am Gastroenterological Association, 2022, 20(8).\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":"colorectal cancer (CRC), polyp, small intestinal bacterial overgrowth (SIBO), breath test, microbiota, hydrogen, methane","lastPublishedDoi":"10.21203/rs.3.rs-4791552/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4791552/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eColorectal cancers (CRC) have been suggested to be involved with coliform bacteria, while the association with small intestinal bacteria is not clear. The study objective was to investigate the relationship between patients with CRC and the gas production characteristics of small intestinal bacteria using the lactulose breath test (LBT).\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eData on age, gender, body mass index (BMI), hydrogen and methane concentrations at various time points, and colonoscopy results of patients with bowel diseases were collected from 2017 through 2023. The gas production characteristics of small intestinal bacteria were analyzed in patients with functional and organic bowel diseases, particularly in those patients with polyps and CRC. Additionally, receiver operating characteristic (ROC) analysis was performed to differentiate between these conditions.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eA total of 274 patients with functional bowel diseases, 274 patients with organic bowel diseases, 214 patients with polyps, and 18 patients with CRC were included. Methane concentrations in patients with organic bowel diseases, whether polyps or CRC, were significantly higher than in those with functional bowel diseases. Conversely, hydrogen concentrations were significantly higher in patients with functional bowel diseases compared to those with organic bowel diseases and polyps at certain time points. The area under the curve (AUC) for the methane concentrations at the 60-minute mark in predicting CRC was 0.7104 (95% confidence interval, 0.6166\u0026ndash;0.8042). Among patients with CRC, hydrogen concentrations were significantly higher in those with CRC compared to those with polyps.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusions\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThere were distinct features of hydrogen and methane production in patients with organic bowel diseases compared to those with functional bowel diseases. Patients with CRC or polyps exhibited higher methane concentrations. Additionally, the LBT appears to be a promising tool for distinguishing functional bowel diseases and CRC.\u003c/p\u003e","manuscriptTitle":"Gas Production Characteristics of Small Intestinal Bacteria in Patients with Colorectal Cancers: A Study Using the Lactulose Breath Test","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-02 13:14:06","doi":"10.21203/rs.3.rs-4791552/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":"c572c6c2-ba98-49a4-a359-e1cd3c7e8891","owner":[],"postedDate":"September 2nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-10T06:38:59+00:00","versionOfRecord":[],"versionCreatedAt":"2024-09-02 13:14:06","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4791552","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4791552","identity":"rs-4791552","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}