CHROMOSOME ALTERATIONS IN BREAST CARCINOMAS - FREQUENT INVOLVEMENT OFDNA LOSSES INCLUDING CHROMOSOMES 4Q AND 21Q

Comparative genomic hybridization was applied to map DNA gains and los ses in 39 invasive ductal breast carcinomas. Frequent abnormalities in cluded gains on chromosomal regions 1q, 8q, 11q12-13, 16p, 19, 20q and X as well as frequent losses on 1p, 5q, 6q, 9p, 11q, 13q and 16q. Fur thermore, frequent losses on 4q (20 cases) and 21q (14 cases) were fou nd for the first time in this tumour type. High copy number amplificat ions were observed at 8q12-24, 11q11-13 and 20q13-ter. Highly differen tiated tumours were associated with gains on Iq and 11q12-13 along wit h losses on 1p21-22, 4q, 13q, 11q21-ter. Undifferentiated breast carci nomas were characterized by additional DNA imbalances, i.e. deletions of 5q13-23, all of chromosome 9, the centromeric part of chromosome 13 including band 13q14 and the overrepresentation of chromosome X. We s peculate that these changes are associated with tumour progression of invasive ductal breast cancer.