Clonal chromosome abnormalities in human breast carcinomas I. Twenty-eight cases with primary disease

Cytogenetic analysis was performed on a selected series of short‐term cultures of primary breast carcinomas from 28 patients. All patients had histopathologically confirmed malignancies, with the majority (25/28 cases) demonstrating infiltrating ductal carcinoma. All 28 cases evidenced clonal chromosome abnormalities, with 10/28 displaying only numeric aberrations, whereas 18/28 displayed clonal structural alterations. In near‐diploid tumors the most common numeric changes were — 17 and — 19. However, trisomy 7 was the only numeric change in two near‐diploid tumors. Structural chromosome alterations were primarily isochromosomes, apparent terminal deletions, and unbalanced non‐reciprocal translocations. Chromosomes 1 (10/18–56%) and 6 (8/18–44%) were most frequently altered in this series. Breakpoints of clonal structural abnormalities were shown to cluster to several chromosome segments, including 1p22‐q11, 3p11, 6p11–13, 7p11‐q11, 8p11‐q11, and 19q13. Analysis of the gain or loss of specific chromosome segments revealed that the most consistent tendency was over‐representation of 1q, 3q, and 6p. © 1993 Wiley‐Liss, Inc.