Lifetime Risk Of Colorectal Cancer Research Articles

Variation in cancer risk between organs can not be explained by the degree of somatic clonal expansion

Somatic clonal expansion refers to the proliferation and expansion of a cell clone within a multicellular organism. Since cancer also results from the uncontrolled proliferation of few cell clones, it is generally believed that aging-associated somatic clonal expansion observed in normal tissues represents a precancerous condition. For instance, hematological malignancy is often preceded by clonal hematopoiesis. However, the precise connection between cancer and somatic clonal expansion remains elusive in solid organs. In this study, we utilized a straightforward method to assess the relative quantitative degrees of clonal expansion in nine human organs. Our findings reveal that the degree of clonal expansion varies across different organs while remaining consistent among different individuals. Contrary to the general belief, we did not identify any significant correlation between lifetime cancer risk and the degree of lifetime somatic clonal expansion. For example, the lifetime risk of colorectal cancer is approximately 20 times higher than that of esophageal cancer, yet the former exhibited the lower degree of clonal expansion than the latter. Our results suggest that somatic clonal expansion represents an evolutionary process distinct from carcinogenesis in normal tissues, providing novel perspectives on precancerous conditions.

D239Y germline variant of NTHL1 glycosylase increases susceptibility to colorectal cancer in mice

Introduction: Persistent genotoxic stress leads to spontaneous DNA damage, which occurs on the order of 104−105 events per cell per day. The base excision repair is the first responder in the repair mechanisms after DNA damage, with DNA glycosylase being the first step in the repair process by binding to the DNA, cleaving the N-glycosidic bond and removing the oxidized pyrimidine DNA lesions. NTHL1 is a pivotal bifunctional DNA glycosylase enzyme involved in base excision repair mechanism. NTHL1 tumor syndrome is characterized by an increased lifetime risk for colorectal cancer (CRC), breast cancer, and colorectal polyposis. A rare rs3087468 polymorphism (D239Y) exhibits no glycosylase activity and may act as a dominant-negative mutation. Hypothesis: NTHL1-D239Y variant conforms susceptibility to inflammation-associated colorectal cancer. Methods: 6-8 weeks/old male and female C57BL/6 wild-type (WT, NTHL1WT/WT), heterozygous (NTHL1WT/D239Y), or homozygous (NTHL1D239Y/D239Y) knock-in mice were injected with 7.5mg/kg azoxymethane (AOM) followed by three cycles of alternating 2.5% dextran sulfate sodium (DSS, 5 days) and normal drinking water (14 days). We monitored body weight, collected fecal samples for microbial 16S rRNA amplicon sequencing, and analyzed colon length and number/size of polyps at euthanasia. The histology score was assessed by an unbiased pathologist to evaluate inflammation and tumor development. Blood samples were used to evaluate micronuclei formation. Results: NTHL1WT/D239Y and NTHL1D239Y/D239Y mice showed more pronounced weight loss starting from the 2nd DSS cycle. The number and size of polyps in the distal colon of NTHL1WT/D239Y and NTHL1D239Y/D239Y male mice were increased compared to WT littermates. NTHL1D239Y/D239Y females, but not males, showed increased polyp number compared to NTHL1WT/D239Y mice. No statistical difference was observed in the polyps’ size. Tumors extending into the proximal colon were observed uniquely in NTHL1D239Y/D239Y females. On the other hand, only NTHL1WT/D239Y males developed high adenomas in the distal colon compared to WT males. Interestingly, only NTHL1D239Y/D239Y males showed statistical difference in micronucleated normochromatic erythrocytes compared to WT mice. NTHL1 genotype did not significantly affect fecal microbial α- or β-diversity or colitis score and colon length in either gender. Conclusion: Our data suggest that NTHL1-D239Y variant confers a complex, zygosity- and sex-dependent susceptibility risk for inflammation-associated colorectal cancer that may be intrinsic and independent of changes in the gut microbiota. In females, it promotes more proximal tumor location, while in males, it promotes the size and tumor progression. 5P30CA023074 (JBS), Phoenix Women's Board of the Steele Children's Research Center (FKG). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 3872: Multi-ancestral origins of colorectal lesionsMulti-ancestral origins of colorectal lesions

Abstract The widely accepted paradigm that cancer initiation is a monoclonal event has not been definitively resolved. In sporadic cancers this is due to the requirement for longitudinal sampling to study this occult process, which occurs over years to decades. Individuals with familial adenomatous polyposis (FAP) possess a germline APC mutation, leading to hundreds of colonic polyps in adolescence and a 100% lifetime risk of colorectal cancer. Resected colons from FAP patients contain normal mucosa, benign and dysplastic polyps that embed the natural history of colorectal tumorigenesis at different points of malignant progression. Through genome sequencing of 127 independent polyps or mucosa samples from six FAP patients, we characterized the genomic landscape, relative timing of somatic alterations, and clonal dynamics in normal, dysplastic, and invasive colon tissue. Comparison with multi-region sequencing data from FAP patients and sporadic colorectal adenomas and carcinomas indicates similar molecular profiles, with canonical cancer driver genes present across benign and dysplastic premalignant lesions and shared mutational orders. Pairwise sample comparisons and phylogenetic reconstructions revealed extensive heterogeneity and subclonal sharing within a patient’s benign and dysplastic lesions, irrespective of location in the colon. These data imply that polyps were initiated from multiple cells from distinct lineages whose most recent common ancestor arose during development. We corroborate these findings using a mechanistic mathematical model, which infers polyclonality in 100% of benign and 83% of dysplastic samples. Based on these findings, we propose a conceptual model of the multi-ancestral origin of intestinal malignancies. Citation Format: Ryan O. Schenck, Aziz Khan, Aaron Horning, Edward D. Esplin, Debra Van Egeren, HTAN–FAP Consortium, William Greenleaf, James M. Ford, Michael P. Snyder, Christina Curtis. Multi-ancestral origins of colorectal lesionsMulti-ancestral origins of colorectal lesions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3872.

Abstract B008: The polyclonal path towards malignant transformation in familial adenomatous polyposis

Abstract The widely accepted paradigm that cancer initiation is a monoclonal event has not been definitively resolved. This is largely due to the limitations of experimental systems to study cancer initiation, a definitively transient step in tumorigenesis. Individuals with familial adenomatous polyposis (FAP) possess a germline APC mutation, leading to hundreds of colonic polyps in adolescence and an eventual 100% lifetime risk of colorectal cancer. As such, total colectomies are performed once polyp burden becomes unmanageable and provide the resected colons from FAP donors provide a source of histologically normal mucosa, benign and dysplastic polyps, and, on rare occasions, adenocarcinomas, and serve as an exemplary model disease to understand human tumorigenesis. Through whole genome sequencing of 123 independent samples from six patients, we reveal the polyclonal origins of tumorigenesis in FAP. We characterize and contrast the genomic landscape and relative timing of driver mutation acquisition across normal to dysplastic and invasive colon tissue and compare this with multi-region sequencing data from sporadic colorectal cancers (CRC). We find that only early sporadic CRC drivers are common across the more heterogeneous premalignant stages. Selection, as assessed based on the ratio of nonsynonymous to synonymous mutations (dN/dS), is higher in benign than dysplastic FAP lesions and in sporadic adenomas relative to carcinomas. Phylogenetic reconstruction and pairwise sample comparisons reveal extensive heterogeneity and subclonal sharing within a patient’s benign and dysplastic lesions. Using a mechanistic mathematical model, we infer polyclonality for 90-100% of benign and 53-83% of dysplastic samples. Based on these findings, we propose a conceptual framework for the polyclonal origin of intestinal malignancies where inconsequential mutations, arising during colon formation in utero, are present across the colon and are valuable markers to uncover polyclonal ancestry. Citation Format: Ryan O. Schenck, Aziz Khan, Aaron M. Horning, Edward D. Esplin, HTAN Consortia, William J. Greenleaf, James M. Ford, Michael P. Snyder, Christina Curtis. The polyclonal path towards malignant transformation in familial adenomatous polyposis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr B008.

Surveillance Compliance and Quality of Life Assessment Among Surgical Patients with Familial Adenomatous Polyposis Syndrome.

Familial adenomatous polyposis (FAP) syndrome has a near-100% lifetime risk of colorectal cancer. Early surveillance and prophylactic surgery have been advocated to reduce this risk. However, the surveillance practices among FAP individuals in Saudi Arabia are unknown. We aimed to explore surveillance compliance in our population, as well as the disease impact on their quality of life (QoL). All patients with FAP who underwent surgical resection at King Saud University Medical City between 2016 and 2022 were included. Demographic data, clinical features, family history, and compliance with surveillance were collected and analyzed. QoL questionnaires: Short-form health survey (SF-36) and European Organization for Research and Treatment (EORTC) were conducted by phone interview. A total of 14 patients were included with an average age of 25years. Three patients (21.4%) were the first of their family members to develop FAP. Nine patients (64%) were untested for genetic mutation due to lack of referral to geneticists. The compliance rate toward both pre-operative colonoscopy and upper endoscopy were 78%. However, 38% and 27% compliance rates were observed toward initial and post-operative colonoscopy, respectively. The compliance rate was 14% toward thyroid ultrasound. QoL scores varied among patients, with a mean score above 60 across all SF-36 domains. An overall poor compliance was observed among our participants, particularly toward thyroid ultrasound. Increased health awareness and patient education are essential. In addition, the importance of surveillance and genetic counseling should be emphasized among physicians treating these patients.

Tumor Testing and Genetic Analysis to Identify Lynch Syndrome Patients in an Italian Colorectal Cancer Cohort.

Lynch syndrome (LS) is an inherited cancer susceptibility syndrome caused by germline mutations in a DNA mismatch repair (MMR) gene or in the EPCAM gene. LS is associated with an increased lifetime risk of colorectal cancer (CRC) and other malignancies. The screening algorithm for LS patient selection is based on the identification of CRC specimens that have MMR loss/high microsatellite instability (MSI-H) and are wild-type for BRAFV600. Here, we sought to clinically and molecularly characterize patients with these features. From 2017 to 2023, 841 CRC patients were evaluated for MSI and BRAFV600E mutation status, 100 of which showed MSI-H. Of these, 70 were wild-type for BRAFV600. Among these 70 patients, 30 were genetically tested for germline variants in hereditary cancer predisposition syndrome genes. This analysis showed that 19 of these 30 patients (63.3%) harbored a germline pathogenic or likely pathogenic variant in MMR genes, 2 (6.7%) harbored a variant of unknown significance (VUS) in MMR genes, 3 (10%) harbored a VUS in other cancer-related genes, and 6 (20%) were negative to genetic testing. These findings highlight the importance of personalized medicine for tailored genetic counseling, management, and surveillance of families with LS and other hereditary cancer syndromes.

Colitis-Associated Colorectal Cancer Survival is Comparable to Sporadic Cases after Surgery: a Matched-Pair Analysis

BackgroundInflammatory bowel disease (IBD) confers an increased lifetime risk of colorectal cancer (CRC). The pathogenesis of colitis-associated CRC is considered distinct from sporadic CRC, but existing is mixed on long-term oncologic outcomes. This study aims to compare clinicopathological characteristics and survival between colitis-associated and sporadic CRC. MethodsData was retrospectively extracted and analyzed from a single institutional database of patients with surgically resected CRC between 2004 and 2015. Patients with IBD were identified as having colitis-associated CRC. The remainder were classified as sporadic CRC. Propensity score matching was performed. Univariate and survival analyses were carried out to estimate the differences between the two groups. ResultsOf 2275 patients included in this analysis, 65 carried a diagnosis of IBD (2.9%, 33 Crohn’s disease, 29 ulcerative colitis, 3 indeterminate colitis). Average age at CRC diagnosis was 62 years for colitis-associated CRC and 65 for sporadic CRC. The final propensity score matched cohort consisted of 65 colitis-associated and 130 sporadic CRC cases. Patients with colitis-associated CRC were more likely to undergo total proctocolectomy (p < 0.01) and had higher incidence of locoregional recurrence (p = 0.026) compared to sporadic CRC patients. There were no significant differences in time to recurrence, tumor grade, extramural vascular invasion, perineural invasion, or rate of R0 resections. Overall survival and disease-free survival did not differ between groups. On multiple Cox regression, IBD diagnosis was not a significant predictor of survival. ConclusionsPatients with colitis-associated CRC who undergo surgical resection have comparable overall and disease-free survival to patients with sporadic CRC.

Accelerated tumorigenesis in a colorectal cancer model in Siglec-E knockout mice

Abstract The lifetime risk for colorectal cancer in the United States is approximately 4%. Individuals with Inflammatory Bowel Disease, including Ulcerative Colitis and Crohn’s Disease, have a substantially increased risk of developing colorectal cancer. The mechanisms for accelerated tumorigenesis due to enhanced inflammation are not fully characterized. Siglecs (sialic acid immunoglobulin lectin-like proteins) are a family of inhibitory receptors that are negative regulators of the immune response. Siglec-E is an inhibitory receptor that is expressed by innate immune cells, including monocytes, macrophages, neutrophils and dendritic cells. Interestingly, mice deficient in Siglec-E have accelerated development of tumors and reduced survival in a spontaneous mouse model of colorectal cancer (TS4-cre LSL-KRas G12DAPClox 468/wt). While tumors develop at approximately six months in mice with Siglec-E, tumors develop at approximately two months in Siglec-E knockout mice. Initial results indicate that Siglec-E knockout mice also have accelerated gut inflammation using the DSS colitis model as compared to WT mice. Current studies are examining inflammation that develops during tumorigenesis in Siglec-E knockout mice. Center for Biomedical Discovery NIH R01 CA243545-01A1 to VSS Mayo Clinic Graduate School of Biomedical Sciences Deans fellowship: Initiative for maximizing student development (IMSD) R25 GM055252-26 Doyon Foundation

Waiting times in a branching process model of colorectal cancer initiation

We study a multi-stage model for the development of colorectal cancer from initially healthy tissue. The model incorporates a complex sequence of driver gene alterations, some of which result in immediate growth advantage, while others have initially neutral effects. We derive analytic estimates for the sizes of premalignant subpopulations, and use these results to compute the waiting times to premalignant and malignant genotypes. This work contributes to the quantitative understanding of colorectal tumor evolution and the lifetime risk of colorectal cancer.

Abstract 3797: Fecal miRNA profiles and gut metagenome composition in Lynch syndrome: results from a mouse model study and human subjects

Abstract Bsacground: Lynch Syndrome (LS) is an inherited cancer syndrome associated with an increased lifetime risk of colorectal cancer (CRC) and characterised by germline mutations in DNA mismatch repair (MMR) genes. Abnormalities in the function of MMR genes lead to errors during DNA replication, including microsatellite instability. Despite regular colonoscopies, up to 15% of LS patients still develop CRC. Gut microbiome, bowel inflammation, the environment and host genetic and epigenetic factors are involved in CRC development. In this sense, the concomitant analysis of stool host microRNA (miRNA) profiles and gut microbiome composition may arise to the identification of specific fecal markers in LS explaining the molecular basis for the development of cancer in these patients. PURPOSE: In the present study, the fecal miRNome and microbiome were characterized in a time progression in an in vivo model using a mismatch repair deficient mice model that recapitulates human LS. The main aim was to evaluate the changes and crosstalk of miRNAs released in the stool by the host and the microbial population residing in the gut during the carcinogenesis process induced in animals. Findings in mice were compared and correlated to data obtained from a cohort of human subjects affected by LS. Methods: We used an in vivo model for LS based on a conditional knockout mouse with the tissue-specific inactivation of Msh2 (Msh2LoxP) in the intestinal mucosa, combining Msh2LoxP allele with the Villin-Cre transgene (VCMsh2LoxP). Stool from mice were collected at different time points (6, 9 and 12 months of age). Small RNA-sequencing (sRNA-seq) and shotgun metagenomics analyses were performed in stool from all samples. In concomitance, we collected 78 stool samples of clinically diagnosed LS subjects, at different follow up time. At the sampling, 36 resulted negative for colorectal adenomas/lesions, 12 were negative but with a previous history of lesions, 23 presented a neoplasia and 6 developed a lesion in the follow-up. Twenty-two stool samples from healthy subjects were used as controls. Results: In mice, preliminary results from sRNA-seq and metagenomics analyses showed several dysregulated miRNAs and differential microbial relative abundances, either between VCMsh2loxP and controls or at different time points. In humans, we identified 41 and 17 miRNAs respectively up- and downregulated in LS subjects who presented a lesion compared to those not having any lesion at follow-up. In the same comparison the metagenomic data showed significantly different microbial abundances, including those of Eubacterium ramulus. Conclusions: This is the first study characterizing the concomitant alterations in microbial composition and host miRNome overtime in relation to the onset of cancerous/precancerous lesions due to LS. Citation Format: Giulia Francescato, Giulio Ferrero, Marc Beltrà, Sonia Tarallo, Giulia Piaggeschi, Carla Di Battista, Antonio Francavilla, Carlijn Bruggeling, Fabio Penna, Barbara Pardini, Paola Costelli, Annemarie Boleij, Alessio Naccarati. Fecal miRNA profiles and gut metagenome composition in Lynch syndrome: results from a mouse model study and human subjects. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3797.

Internet-based assessment tools for predicting colorectal cancer risk: How do they communicate individualized risk to the young adult?

72 Background: Online prediction tools for cancer risk can inform individuals about their risk and potentially encourage adoption of risk-modifying health behavior. The Colorectal Cancer Risk Assessment Tool (CCRAT) is an interactive tool developed by the National Cancer Institute for estimating colorectal cancer (CRC) risk for individuals between the ages of 45 and 85 without high risk predisposing conditions. Given the rising incidence of CRC among young adults under age 50, we aimed to investigate the performance of CCRAT in estimating their CRC risk. Methods: An institutional protocol prospectively enrolled 563 patients newly diagnosed with non-hereditary CRC and administered a health behavior questionnaire at baseline. Self-reported demographics, diet and physical activity, medication use, and family history were extracted and entered into the CCRAT ( https://ccrisktool.cancer.gov/calculator.html ) to calculate their predicted 5-year and lifetime CRC risks. Health behaviors and the predicted CRC risks in reference to the population average were compared among three groups: youngest- (aged 18-44, N = 276, 49%), young- (aged 45-50, N = 178, 32%), and older-onset (aged &gt; 50, N = 109; 19%). Results: The patient groups did not significantly differ in gender or in family history of CRC, but the youngest group had significantly more non-White patients (27, 22, vs. 19%; p = 0.008) and distal tumors (80, 76 and 65%; p = 0.05). The youngest and young groups had a higher prevalence of morbid obesity (18 and 15% vs. 12%; p = 0.002) and active smokers (6 and 8% vs. 3%; p = 0.005). There were no significant differences in vegetable intake, moderate exercise, NSAID use, or female hormone use. The 5-year CRC risk was correctly predicted as “higher than average population” for a significantly smaller proportion of the youngest (42%) and young (45%) patients, when compared to their older counterpart (71%; p &lt; 0.001). Similarly, the tool communicated “higher than average” lifetime risk for CRC in only 56 and 60% of the youngest and young patients, but 72% of the older ones (p = 0.021). Conclusions: The existing risk prediction tool inadequately communicated CRC risk for adults younger than 50 years of age. Risk factors underlying young-onset CRC likely differ from and extend beyond those as currently assessed. New tools capturing age-specific risk factors are needed to accurately communicate individualized risk and potentially motivate risk-modifying lifestyles.

Massive gastric polyposis in Peutz-Jeghers Syndrome – a case report

Peutz-Jeghers Syndrome (PJS) is a rare autosomal dominant disorder equally affecting males and females with an incidence of 1/25,000 – 1/300,000 births. It is characterised by the development of hamartomatous polyps of the digestive tract, a lifetime risk of colorectal cancer and other gastrointestinal malignancies, as well as non-gastrointestinal cancers such as breast and ovarian cancers. Intestinal polyposis is very common in PJS, however, gastric polyps occur in less than 20% of patients with massive polyposis rarely reported. We report a case of massive gastric polyposis in an elderly PJS patient with concurrent and prior intestinal polyps and multiple occurrences of intussusception. The gastric polyps were present in the fundus through to the gastro-eosophageal junction. Microscopy demonstrated arborising branches of smooth muscle covered by disorganised mucosa – consistent with PJS polyps. The largest gastric polyp showed architectural complexity and nuclear atypia suggestive of high-grade dysplasia. An intrapolyp adenocarcinoma had been biopsied from the gastric fundus two months prior but no residual invasion was present in the gastrectomy specimen. It is important for pathologists to be aware of the association between PJS and gastric polyps in which dysplasia and malignancy can develop.

Hereditary Colorectal Cancer Syndromes: Molecular Genetics and Precision Medicine.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Hereditary CRC syndromes account for approximately 5-10% of all CRC, with a lifetime risk of CRC that approaches 50-80% in the absence of endoscopic or surgical treatment. Hereditary CRC syndromes can be phenotypically divided into polyposis and non-polyposis syndrome, mainly according to the conditions of polyps. The typical representatives are familial adenomatous polyposis (FAP) and Lynch syndromes (LS), respectively. Over the past few decades, molecular genetics enhanced the discovery of cancer-predisposing genes and revolutionized the field of clinical oncology. Hereditary CRC syndromes have been a key part of this effort, with data showing that pathogenic variants are present in up to 10% of cases. Molecular phenotypes of tumors can not only help identify individuals with genetic susceptibility to CRC but also guide the precision prevention and treatment for the development of CRC. This review emphasizes the molecular basis and prevention strategies for hereditary CRC syndromes.

Patterns of DNA mismatch repair protein expression for primary and recurrent colorectal cancer at an advanced surgical unit: A retrospective audit.

Lynch syndrome is an inherited cancer syndrome associated with an increased lifetime risk of colorectal cancer (CRC) and characterized by germline mutations to one of four DNA mismatch repair (MMR) genes. Immunohistochemical (IHC) testing is used to screen for Lynch syndrome; however, despite routine completion following resection of primary CRC, it is only variably completed following resection of recurrent disease. This may be significant, as MMR protein expression can change from primary to recurrent CRC. The primary aim of this study is to investigate how MMR profiles change from primary to recurrent CRC; the secondary aim is to assess rates of MMR testing of primary and recurrent disease. We conducted a retrospective analysis of patients undergoing surgery for recurrent CRC from 2018-19 at a high-volume institution. MMR profiles were obtained following both primary and recurrent resection of CRC, and MMR protein expression was evaluated from both time points. A total of 107 patients met the inclusion criteria and IHC results were obtained for both primary and recurrent resections in 85 cases. MMR profiles changed in nine patients (10.6%), with a loss of staining from primary to recurrent disease in six (7.1%) and a gain of staining in three (3.5%). IHC testing was completed following 88.7% of primary and 39.3% of recurrent resections. MMR profiles can change from primary to recurrent CRC and repeat MMR testing for recurrent CRC is completed in only a minority of cases.

Using Online Colorectal Cancer Risk Calculators to Guide Screening Decision-Making

BackgroundSeveral online calculators estimate colorectal cancer risk, but their consistency is unknown. Our objectives were to quantify the variation in predicted risk and to determine which calculators are best used in the clinical setting. MethodsWe used the Google search engine to identify online colorectal cancer risk calculators and assessed the output of each for 3 hypothetical screening scenarios (low-, average-, and high-risk), varied by age (50, 62, 75 years), sex, and race (Black, White), with risk levels based on risk-appropriate values for variables in each model. Estimated risks for models within a given scenario were rated as consistent or inconsistent based on comparison with either the absolute magnitude of difference or average lifetime risk of colorectal cancer. Summary statistics for consistent and inconsistent estimates were compared using chi-square and Fisher's exact tests. ResultsWe identified 5 online colorectal cancer risk calculators. Inconsistencies were found in none of 5-year, 19% of 10-year, and 81% of lifetime colorectal cancer risk estimate comparisons (P < .001). For a 50-year-old, 22% of risk estimate comparisons were inconsistent, vs 33% for a 62-year-old, and 36% for a 75-year-old (P = 0.14). ConclusionsOnline colorectal cancer risk models are more consistent in predicting colorectal cancer risk for 5- and 10-year time frames compared with lifetime. For a US population, the National Cancer Institute's Colorectal Cancer Risk Assessment Tool is a rigorously developed calculator that can be used in the clinical setting to provide 5-year and lifetime risk estimates.

Fecal Microbiome Associated with Both Colon Adenomas and Lifetime Colorectal Cancer Risk.

Increasing data indicates the gut flora including bacteria and fungi combined with environmental factors are important in the pathogenesis of colorectal cancer (CRC). Understanding differences in the microbiome in patients with colon neoplasia will foster the development of biomarkers for early detection. Determine the association of microbiome with presence of adenomas and predicted CRC risk. In subjects referred for colonoscopy, the NCI CRC risk assessment tool was completed and stool for microbiome analysis as well as fecal immunochemical test (FIT) were collected. We calculated the microbiome alpha diversity using the Shannon index as well as individual bacterial and fungal species. Among 34 patients, we identified 10 with one or more adenomas. Only 2 patients were FIT positive. The median predicted lifetime CRC risk was 2.75% and the prevalence of adenoma was higher in the fourth quartile (P < 0.001). The measured alpha diversity was somewhat higher in patients with adenomas (P = 0.07). We identified 4 bacterial species with an increased relative abundance among patients with adenomas [P < 0.5]. Lifetime CRC risk was associated with 2 specific bacterial species, P. distasonis & E. hermannii [P = 0.05 & 0.09, respectively]. No associations were seen with fungal species and adenoma prevalence or lifetime CRC risk. In addition to a strong correlation of predicted CRC risk and adenoma prevalence, we also found important differences in specific bacterial species and both adenoma prevalence and CRC risk. Larger trials are needed to potentially implement further data in the clinical setting.

Cumulative incidence and risk factors for pouch adenomas associated with familial adenomatous polyposis following restorative proctocolectomy.

BACKGROUNDThe emergence of restorative total proctocolectomy has significantly reduced the lifetime colorectal cancer risk associated with familial adenomatous polyposis (FAP). However, adenomas may develop in the ileal pouch over time and may even progress to carcinoma. We evaluated the cumulative incidence, time to development, and risk factors associated with ileal pouch adenoma.AIMTo evaluate the cumulative incidence, time to development, and risk factors associated with pouch adenoma.METHODSIn this retrospective, observational study conducted at a tertiary center, 95 patients with FAP who underwent restorative proctocolectomy at our center between 1989 and 2018 were consecutively included. The mean follow-up period was 88 mo.RESULTSPouch adenomas were found in 24 (25.3%) patients, with a median time of 52 mo to their first formation. Tubular adenomas were detected in most patients (95.9%). There were no high-grade dysplasia or malignancies. Of the 24 patients with pouch adenomas, 13 had all detected adenomas removed. Among the 13 patients who underwent complete adenoma removal, four (38.5%) developed recurrence. Among 11 (45.8%) patients with numerous polyps within the pouch, seven (63.6%) exhibited progression of pouch adenoma. The cumulative risks of pouch adenoma development at 5, 10, and 15 years after pouch surgery were 15.2%, 29.6%, and 44.1%, respectively. Severe colorectal polyposis (with more than 1000 polyps) was a significant risk factor for pouch adenoma development (hazard ratio, 2.49; 95% confidence interval: 1.04-5.96; P = 0.041).CONCLUSIONPouch adenomas occur at a fairly high rate in association with FAP after restorative proctocolectomy, and a high colorectal polyp count is associated with pouch adenoma development.

Abstract 5631: Immunomodulatory activity of sulindac plus erlotinib for colon cancer prevention in familial adenomatous polyposis

Abstract Familial adenomatous polyposis (FAP) is an autosomal dominant disorder caused by germline mutation in Adenomatous Polyposis Coli (APC)1. Patients with FAP have a nearly 100% lifetime risk of colorectal cancer (CRC) due to the formation of hundreds to thousands of adenomatous polyps in the gastrointestinal tract2. A clinical trial in FAP patients demonstrated that Cox-1/2 inhibitor sulindac (SUL) plus EGFR inhibitor erlotinib (ERL) reduced polyp burden significantly in the colon and small intestine (SI), but toxicity issues raised concerns for durable long-term CRC interception3. In the Apc-mutant polyposis in rat colon (Pirc) rat model of FAP, we determined low-dose regimens of ERL+SUL that were both safe and efficacious4. In the current investigation, the lowest tested dose of dietary SUL (125 ppm continuously) plus ERL (5 mg/kg twice weekly), given at one-half the SUL clinical dose and one-fourth of the ERL clinical dose, administered for 46 weeks respectively, demonstrated good inhibition of tumor burden in the colon (&amp;gt;85% efficacy, p&amp;lt;0.05) and SI (&amp;gt;94% efficacy, p&amp;lt;0.05) compared to untreated controls. Moreover, treatment normalized organ weights and hematocrits that were altered in the untreated AIN controls.Recently, ERL5 and SUL6 were individually demonstrated to increase the recruitment of inflammatory immune cells in mouse models of lung and colon cancer, respectively. However, ERL+SUL in combination was not investigated in the context of immune cell infiltration and polarization. Our preliminary IHC data in the Pirc model indicated increased recruitment of CD8+ T cells in colon polyps by SUL 250 ppm + ERL 42 mg/kg once a week. RT-qPCR and immunoblotting analysis of colon polyps obtained from the low-dose combination of SUL 125 ppm + ERL 5 mg/kg twice weekly demonstrated increased CD4 expression and concurrently decreased oncogenic IL-17 expression and tumor associated macrophage markers (CD163 and CD206) (P&amp;lt;0.05 vs control). Additional immune markers will be identified and validated via CyTOF. We hypothesize that low-dose combination of SUL+ERL can enhance the recruitment of immune cells into early adenomatous colon and SI polyps, providing an effective immunointerception strategy, with potential clinical relevance for FAP patients before or after colectomy. Acknowledgements Research supported by NCI Contract Number 75N91019D00021, Task Order 75N91019F00130. 1.Groden J et al., Cell 1991; 66:589-600.2.Jasperson KW et al., Gastroenterology 2010; 138:2044-2058.3.Samadder NJ et. al., JAMA 2016; 315:1266-75.4.Ulusan AM et. al., Cancer Prev Res (Phila). 2021; 14:325-336.5.Ayeni D et al., J Immunother Cancer 2019; 7:172.6.Yi B et al., Mol Cancer Ther 2021; Apr 20. Citation Format: Chakrapani Tripathi, Roderick H. Dashwood. Immunomodulatory activity of sulindac plus erlotinib for colon cancer prevention in familial adenomatous polyposis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5631.

Expression of Autophagic and Inflammatory Markers in Normal Mucosa of Individuals with Colorectal Adenomas: A Cross Sectional Study among Italian Outpatients Undergoing Colonoscopy.

Colorectal cancer (CRC) ranks among the three most common cancers in terms of both cancer incidence and cancer-related deaths in Western industrialized countries. Lifetime risk of colorectal cancer may reach 6% of the population living in developed countries. In the current era of personalized medicine, CRC is no longer considered as a single entity. In more recent years many studies have described the distinct differences in epidemiology, pathogenesis, genetic and epigenetic alterations, molecular pathways and outcome depending on the anatomical site. The aim of our study is to assess in a multidimensional model the association between metabolic status and inflammatory and autophagic changes in the normal colorectal mucosa classified as right-sided, left-sided and rectum, and the presence of adenomas. One hundred and sixteen patients undergoing colonoscopy were recruited and underwent a complete serum lipid profile, immunofluorescence analysis of colonic biopsies for MAPLC3 and myeloperoxidase expression, matched with clinical and anthropometric characteristics. Presence of adenomas correlated with cholesterol (total and LDL) levels, IL-6 levels, and MAPLC3 tissue expression, especially in the right colon. In conclusion, serum IL-6 amount and autophagic markers could be good predictors of the presence of colorectal adenomas.

Accelerated tumorigenesis in a colorectal cancer model in Siglec-E knockout mice

Abstract The lifetime risk for colorectal cancer in the United States is approximately 4%. Individuals with Inflammatory Bowel Disease, including Ulcerative Colitis and Crohn’s Disease, have a substantially increased risk of developing colorectal cancer. The mechanisms for accelerated tumorigenesis due to enhanced inflammation are not fully characterized. Siglecs (sialic acid immunoglobulin lectin-like proteins) are a family of inhibitory receptors that are negative regulators of the immune response. Siglec-E is an inhibitory receptor that is expressed by innate immune cells, including monocytes, macrophages, neutrophils and dendritic cells. Interestingly, mice deficient in Siglec-E have accelerated development of tumors and reduced survival in a spontaneous mouse model of colorectal cancer (TS4-cre LSL-KRasG12D APClox468/wt). While tumors develop at approximately 6 months in mice with Siglec-E, tumors develop at approximately two months in Siglec-E knockout mice. Initial results indicate that Siglec-E knockout mice also have accelerated gut inflammation using the DSS colitis model as compared to WT mice. Current studies are examining inflammation that develops during tumorigenesis in Siglec-E knockout mice.