Risk of metachronous colorectal cancer after surgical resection of index rectal cancer in Lynch syndrome: a multicenter retrospective study in Japan

This study evaluated the risk of metachronous colorectal cancer (CRC) after resection of index (first) rectal cancer in patients with Lynch syndrome (LS). Clinicopathological data of patients with genetically proven LS were retrospectively analyzed in this multicenter Japanese study. The cumulative incidence of metachronous CRC and the overall survival were compared between patients with index rectal cancer (rectal group) and those with index colon cancer (colon group). The median age at index CRC surgery was lower in the rectal group than in the colon group (37 vs. 46 years old, P = 0.01). The cumulative 5-, 10-, and 20-year incidences of metachronous CRC were 3.5