Clinical features of biliary tract cancer in Japanese individuals with Lynch syndrome

Biliary tract cancer (BTC) is a Lynch syndrome (LS)-associated cancer with a high mortality rate. This study aimed to clarify the clinical features of BTC in individuals with LS and to discuss its management.

We obtained data from genetically verified Japanese individuals with LS who were diagnosed at a single institution, between January 2003 and April 2021. Moreover, 21 individuals with sporadic BTC (n=15) and LS associated BTC (n=6) underwent microsatellite instability (MSI) testing.

Among 92 individuals with LS, 6 individuals with MLH1 variants developed BTCs (10 lesions, male/female, 2:1). The median age at diagnosis of initial BTC was 69 years (range, 34-78 years). Histological examination revealed a predominance of differentiated adenocarcinoma (89%). Then, 2 individuals had multiple BTCs. All available 7 BTC lesions showed high-frequency of microsatellite instability (MSI-H). MLH1 carriers showed a 7.2% cumulative risk of BTC development at an age of 70 years. Five of the six individuals died of BTC.

MSI analysis could facilitate LS identification in individuals with BTC. Surveillance for BTC should be considered for MLH1 carriers in Japan.