FLUORESCENCE IN-SITU HYBRIDIZATION STUDIES ON BREAST-TUMOR SAMPLES FOR DISTINGUISHING BETWEEN DIFFERENT SUBSETS OF BREAST-CANCER

OBJECTIVE: To evaluate fluorescence in situ hybridization for distingu ishing between malignant and benign breast tumors and determining gene tic subgroups of breast cancers. STUDY DESIGN: Touch preparations from 94 surgically removed breast tumors (17 benign and 77 malignant) were hybridized with a DNA probe specific for centromeric DNA sequences of chromosome 1. Twenty samples were additionally hybridized with a chro mosome 9-specific probe. RESULTS: We investigated the heterogeneity of the cell populations on the basis of the number of signals per nucleu s. All benign tumors showed two signals per nucleus. In contrast, carc inomas revealed a broad spectrum of hybridization patterns. Some showe d almost exclusively two signals per nucleus, and others exceeded four signals. CONCLUSION: The hybridization patterns of individual tumors can be used for defining different subsets of breast cancer. The resul ts may have prognostic impact, leading to ''molecular-cytogenetic grad ing'' of breast cancer.