MICROSATELLITE INSTABILITY AND PATHOLOGICAL ASPECTS OF BREAST-CANCER

Genomic instability plays a key role in hereditary nonpolyposis colore ctal cancer and in a significant sub-set of non-hereditary colorectal tumors. Recent evidence suggests that microsatellite instability also occurs in various sub-sets of common, non-hereditary forms of extra-co lorectal carcinoma. To investigate the role of microsatellite instabil ity in breast cancer, and to correlate this type of alteration with cl inicopathological characteristics, including tumor proliferative activ ity, we analyzed the status of 8 different microsatellite loci in 28 c ases of primary mammary carcinoma. For this purpose, microsatellite ba nding patterns were compared in paired breast-cancer/peripheral-blood DNA samples. Microsatellite instability was observed in 6/28 (21%) of the cases. Four of the 6 tumors had low proliferative activity, one ha d high proliferative activity, and in one case proliferative activity values were not available. All chromosomal loci investigated demonstra ted microsatellite instability in one or more representative tumors of the series. Shifts in length larger than 2 bp were the most frequent change. Microsatellite instability significantly correlated with the l obular histotype, and with lymph-node involvement. A trend was also ob served associating microsatellite instability and large tumor size. (C ) 1995 Wiley-Liss, Inc.