MICROSATELLITE INSTABILITY IS ASSOCIATED WITH TUMORS THAT CHARACTERIZE THE HEREDITARY NONPOLYPOSIS COLORECTAL-CARCINOMA SYNDROME

Microsatellite instability implying multiple replication errors (RERphenotype) characterizes a proportion of colorectal carcinomas, partic ularly those from patients with the hereditary non-polyposis colorecta l carcinoma syndrome. We studied the incidence of microsatellite insta bility in more than 500 sporadic tumors representing 6 different types of cancer. Apart from colorectal carcinoma [see the paper by Lothe et al. (Cancer Res., 53: 5849-5852, 1993)] the RER+ phenotype was found in 18% (6 of 33) of gastric carcinomas and 22% (4 of 18) of endometria l carcinomas. In contrast, no evidence of this abnormality was detecte d in cancers of the lung (N = 85), breast (N = 84), and testis (N = 86 ). Importantly, the first three cancers, as opposed to the latter thre e, are characteristic of the hereditary non-polyposis colorectal carci noma syndrome. These findings suggest that the cancers belonging to th e hereditary non-polyposis colorectal carcinoma tumor spectrum may hav e essential pathogenetic steps in common, including a tendency to mult iple replication errors.