eP610 - Case Report of Occurrence of Multiple Adenocarcinoma of the Ileal Pouch in a Patient with Hereditary Colorectal Carcinoma

Purpose/Background: A review of surveillance and guidance protocol for small bowel carcinoma occurring in patients with hereditary colorectal carcinoma following the presentation of three synchronous adenocarcinoma of the ileal pouch - small bowel in patient with Lynch syndrome who has undergone total proctocolectomy with ileal pouch anal anastamosis for multiple carcinomas of the colon.Methods/Interventions: Patient underwent total proctocolectomy ileal pouch anal anastamosis following identification of transverse colon carcinoma and descending colon polyp with high grade dysplasia in 2008. This patient had undergone two prior colon resections for right colon cancer and transverse colon polyp with high grade dysplasia eight year and seven years ago respectively. Patient's tumor staging was T3N1 and was given Folfox therapy by the oncologist. Patient developed multiple skin cancer and sebaceous cyst cancer which led to the genetic counseling. Patient's cousin has had colon cancer resected and was found to have genetic mutation of MSH2. Patient's two daughters also have tested positive for genetic mutation of MSH2. Patient was then diagnosed with Muir-Torre syndrome which represents a combination of hereditary non-polyposis colon cancer associated with sebaceous adenocarcinoma. Patient was followed with pouchoscopy and CT-PET scan evaluations. Patient has had small polypoid lesions, primarily adenomas, on pouchoscopy which was done every year for the first three years and every two years until 2018. CT-PET scan evaluations were done yearly for the first five years and were discontinued because of lack of metastatic disease. Patient was not evaluated again until 2021 due to the pandemic wherein two lesions were identified in the ileal pouch; one of them indicated cancer and the other high-grade dysplasia. Imaging showed only thickening of the pouch. Pathological evaluation post-resection identified three adenocarcinomas of the pouch without nodal involvement and classified as T2N0 lesion.Results/Outcomes: Patient did receive chemotherapy to completion and so far has not shown any recurrences locally or distally. Patient is undergoing yearly CTenterography and PET scan.Conclusion/

Discussion: Lifetime risk of developing small bowel cancer in Lynch Syndrome and hereditary colorectal cancer syndrome increases with age and estimated to range between 0.4 - 1% by Lynch, PM and various other authors. This is one hundred times more than the occurrence of small bowel cancer in the general population. The median age of diagnosis of small bowel cancer and hereditary colorectal cancer syndrome is usually between 39-53 years of age, which is about 10-20 years earlier than the general population. This risk is reported to be higher in men than in women. Even though the incidence of small bowel cancer and extracolonic cancer is very high in patients with hereditary colorectal cancer syndrome compared to the general population, the international guidelines have not recommended small bowel surveillance on a routine basis. There is a definite need for an established surveillance protocol and guidance for surveillance for small bowel carcinoma in patients with hereditary colorectal cancer syndrome. With better guidelines and surveillance, the incidence of discovery of small bowel carcinoma can be earlier with resultant better prognosis and survival.