FLUORESCENT IN-SITU HYBRIDIZATION ASSESSMENT OF CHROMOSOME-8 COPY NUMBER IN BREAST-CANCER

Conventional cytogenetics of breast and other solid tumors has been ha mpered by a number of factors. An analysis of breast tumor tissues was therefore undertaken using fluorescent in situ hybridization (FISH). A total of 34 specimens were analyzed using a chromosome 8-specific al pha-satellite probe. Various approaches were tested and compared. Amon g 30 informative samples: 11 infiltrating ductal carcinomas, not other wise specified (NOS), 5 ductal carcinomas in situ, 5 lobular carcinoma s, 3 papillary carcinomas, and 6 benign lesions were studied. Of the 1 1 cases of infiltrating ductal carcinomas (NOS) analyzed, four cases s howed 3 signals, one case showed 4 signals, and the rest showed 2 sign als. Of the 5 cases of ductal carcinoma in situ samples, 1 showed 3 si gnals and the other 4 cases showed 2 signals. All cases of lobular car cinomas, papillary carcinomas, and benign lesions showed 2 signals. We inferred from these data that 36% of the infiltrating ductal carcinom as (NOS) were trisomic and 9% were tetrasomic, whereas 20% of the duct al carcinomas in situ were trisomic. All samples from lobular carcinom as, papillary carcinomas, and the benign lesions were disomic. From ou r preliminary data, it can further be concluded that a subset of breas t cancer is characterized by chromosome 8 trisomy. These data are cons istent with an ever-increasing database on the association of chromoso mal 8 trisomy with other cancers such as leukemia, lymphoma, prostate cancer, ovarian carcinoma, salivary gland tumor, malignant melanoma, d esmoid tumors, and recently gestational trophoblastic disease. It is a lso noted that the ability to analyze formalin-fixed, paraffin-embedde d archival material will enable a more comprehensive cytogenetic study of breast cancer than is currently available.