Clinical and Genetic Implications of DNA Mismatch Repair Deficiency in Biliary Tract Cancers Associated with Lynch Syndrome.

Abstract

Patients with Lynch syndrome (LS) have a significantly elevated lifetime risk of developing biliary tract cancers (BTCs) compared to the general population. However, few studies have characterized the clinical characteristics, genetic features, or long-term outcomes of mismatch-repair deficient (dMMR) cholangiocarcinomas associated with LS. A retrospective review of a prospectively maintained Familial High-Risk GI Cancer Clinic database identified all patients with BTCs evaluated from 2006 to 2016 who carried germline mutations in MLH1, MSH2, MSH6, or PMS2. Eleven patients with BTCs were identified: four perihilar, four intrahepatic, one extrahepatic, one gallbladder, and one ampulla of Vater. All patients had underlying germline mutations and a personal history of a LS-associated malignancy, most commonly (63.3%) colorectal cancer. Ten (90.9%) patients were surgically explored, and margin negative resection was possible in seven (63.3%). Chemotherapy (90.9%) and/or chemoradiation (45.5%) was administered to most patients. Among the seven patients presenting with non-metastatic disease who underwent surgical resection with curative intent, the 5-year overall survival rate was 53.3%. The median overall survival for the four patients not treated with curative intent was 17.2months. dMMR biliary tract cancers associated with LS are rare but long-term outcomes may be more favorable than contemporaneous cohorts of non-Lynch-associated cholangiocarcinomas. Given the emerging promise of immunotherapy for patients with dMMR malignancies, tumor testing for dMMR followed by confirmatory germline testing should be considered in patients with BTC and a personal history of other LS cancers.