Microsatellite instability in cervical and endometrial carcinomas

Microsatellite instability has been found preferentially in tumours associated with the hereditary non‐polyposis‐colorectal‐cancer (HNPCC) syndrome. This phenotype, manifested as new alleles at microsatellite loci, and often the result of a defective mismatch‐repair gene, is seen as allelic mobility shifts during electrophoretic runs. We examined possible alterations at 8 dinucleotide loci mapping to 6 different chromosomes in endometrial cancers (n = 20) and cervical cancers (n = 82). Overall instability was found in 30% of the endometrial cancers and in 6% of the cervical cancers, including 3 (15%) and 2 (2%) tumours, respectively, unstable at more than one locus. In contrast to the endometrial cancer sub‐group, the affected cervical cancers were characterized by one or two new alleles at one or few loci. By DNA ploidy measurements 5 diploid endometrial cancers were microsatellite‐unstable vs. one diploid of 6 unaltered cases (p = 0.015; Fisher's exact test). Our data confirm that a sub‐set of diploid sporadic endometrial cancers are characterized by a mutator phenotype similar to that found in colorectal cancer. In contrast, among cervical cancers, not characterized by the HNPCC‐tumour spectrum, this mutator phenotype is seen infrequently, and positive cases appear to display only minor alterations. Int. J. Cancer 70:499–501. © 1997 Wiley‐Liss Inc.