Direct chromosome analysis of 50 primary breast carcinomas.

Direct chromosome analyses were performed in 50 cases of primary breast carcinoma. Thirty-six cases had modal chromosome counts in the diploid range; the other 14 cases were polyploid. Of the 22 cases with detailed G-banding analyses, the most frequent structural changes involved chromosome 1 (15 of 22), 3 (13 of 22), and 6 (13 of 22). Deletion of chromosome 1p was noted in nine cases, and both 3p- and 6q- were noted in 10 cases.