MICROSATELLITE INSTABILITY IN ENDOMETRIAL CARCINOMAS - FREQUENT REPLICATION ERRORS IN TUMORS OF EARLY-ONSET AND OR OF POORLY DIFFERENTIATEDTYPE/

Endometrial and ovarian carcinomas are common among women belonging to hereditary nonpolyposis colorectal carcinoma (HNPCC) families; tumors developing in them are characterized by genetic instability due to an inherited dysfunction of the DNA-mismatch-repair system. To clarify t he role of similar genetic factors in sporadic forms of gynecological tumors, we examined 77 endometrial and 68 ovarian carcinomas for repli cation error (RER) at five microsatellite loci. RER-positive phenotype s at two or more microsatellite loci were observed in 18 of the endome trial carcinomas, but in only two of the ovarian carcinomas. Among the patients with endometrial carcinomas, the frequency of RER tended to be higher in those under age 50 than in those over age 60. Furthermore , RER was significantly more frequent in poorly differentiated than in well-differentiated tumors (P = 0.008. Fisher's exact test). These da ta suggest that genetic factors characterized by RER are likely to pla y an important role in some endometrial carcinomas, particularly those of early onset and/or of the poorly differentiated type. (C) 1995 Wil ey-Liss, Inc.