S1538 Clinicopathologic Characterization and Genotype Correlation of Duodenal Polyposis Among Hispanics With Familial Adenomatous Polyposis

Abstract

Introduction: Prognosis of individuals with familial adenomatous polyposis (FAP) has improved due to the implementation of specialized surveillance guidelines and prophylactic colectomy. Nonetheless, patients remain at increased risk for other neoplasia such as duodenal cancer. The Spigelman Classification for duodenal polyposis was designed to estimate a patient’s risk for duodenal cancer based on endoscopic and histopathologic findings. Prior studies have reported variation in colonic polyposis burden following a genotype-phenotype pattern according to APC gene mutation. The genotype-phenotype relationship in duodenal polyposis remains less clear. Methods: A total of 71 patients with FAP who had undergone at least one complete esophagogastroduodenoscopy (EGD). Age, sex, tobacco use, alcohol use, and BMI were among the sociodemographic factors evaluated. Study population was divided into mutations in the APC gene between codons 1000-1500 (Group 1) versus mutations before codon 1000 and after codon 1500 (Group 2). All participants were recruited as part of the UPR Medical Sciences Campus IRB approved prospective familiar cancer registry (PURIFICAR - http://purificar.rcm.upr.edu/). Results: Seventy-one patients with genetic diagnosis of FAP were evaluated. Duodenal adenomas were present in 42 (59%) patuents. 120 EGDs were evaluated for the study, with a mean of 1.7 EGDs per patient (Range = 1–4). Patients with duodenal adenomas on EGD were more likely to have APC mutations between codons 1000-1500 (65.7% vs 20%; P = 0.001). Differences in Spigelman stage between the 2 genotype groups were not statistically significant (P-value = 0.86). Furthermore, bivariate analysis of gender, age at last contact, BMI, tobacco use, and alcohol use were not independently associated with Spigelman stage. No cases of duodenal or ampullary cancer were observed after an overall follow-up of 304.6 patient-years. Conclusion: Our study provides the first phenotypic and genotypic characterization of duodenal polyposis among Hispanic patients with FAP. Duodenal polyposis was significantly associated with APC mutations within the 1000-1500 codon cluster. No other clinicodemographic or environmental associations were independently associated with presence of duodenal polyposis; no cases of duodenal cancer were observed in 304.6 patient-years of follow up. Our observations provide insightful information about the impact of APC genetic mutation location and endoscopic surveillance.