[Cancer Risk in Lynch Syndrome-Associated Endometrial Cancer Patients and Their Relatives]

Endometrial cancer(EC)is often the sentinel cancer in women with Lynch syndrome(LS), but the actual incidence of EC as the sentinel cancer in patients with LS is not well-known in Japan. We investigated the history of malignancies and incidence of sentinel cancers in patients with LS-associated EC and their relatives. We examined 8 patients with LS-associated EC between 2005 and 2019. Five of them(63%)had suffered from a cancer other than EC, while 5(63%)had developed a cancer after EC. Seven patients(88%)had EC as the sentinel cancer, while 1(13%)developed colorectal cancer before EC. Among first-degree relatives(15 men and 23 women), 15(40%)had a history of cancer, of whom 7 were women (30%). Five women(22%)had EC, all sentinel. Among second-degree relatives(40 men, 44 women, 14 unknown), 16 (16%)had cancer. Four women(9%)had a history of cancer, of whom 2(5%)had EC, all sentinel. Although we only investigated a few LS cases, the importance of EC as the sentinel cancer was highlighted in Japanese women with LS.