Résumé
Second cancers in patients with microsatellite instable colorectal cancer
Why was the study done? Colorectal cancers (CRC) with deficient mismatch repair system and/or microsatellite instability-high (dMMR/MSI-H) phenotype represent about 12% of CRC. dMMR/MSI-H CRC is due to a germline mutation (Lynch syndrome, LS) or an age-related epigenetic mechanism (sporadic cases). It is well recognized that patients with LS have a high lifetime risk of various cancers but there are no data concerning the risk of a second cancer in sporadic dMMR/MSI-H CRC. What did the researchers do? In a prospective cohort of 484 well-characterized patients with a dMMR/MSI-H CRC, we described their risk of having another primary cancer (APC) according to the LS versus sporadic status. What did the researchers find? Among the 484 patients with dMMR/MSI-H CRC, we identified 24% of patients with a previous or a second primary tumor. Regarding the occurrence of APC, we found no difference between patients with LS-related dMMR/MSI-H CRC group and those with sporadic dMMR/MSI-H CRC. What do the findings mean? It seems important to follow patients with a history of dMMR/MSI-H CRC due to the high risk of second tumors, even in sporadic cases.