COMPARISON OF CHROMOSOME-1 ANEUSOMY DETECTED BY INTERPHASE CYTOGENETICS AND DNA-PLOIDY IN CARCINOMA OF THE BREAST

Aneuploidy is an important prognostic factor in many cancers. Chromoso me 1 abnormalities are present in most breast carcinomas. These may be part of a nonspecific increase in DNA (aneuploid status) or represent a restricted chromosomal abnormality. In 16 breast carcinomas we comp ared chromosome 1 aneusomy with ploidy status, Patients were selected from a mammographically screened population and interphase tumour nucl ei were studied by in situ hybridization using a chromosome 1 pericent romeric probe. Ploidy status was assessed by image cytometry on disagg regated cells from paraffin blocks. Of eight cases showing chromosome 1 aneusomy, six (75%) were aneuploid and two diploid. Six (75%) of the eight eusomic cases were aneuploid. This study demonstrates that chro mosome 1 aneusomy does not always reflect a gross aneuploid status but , in some tumours, is part of a more restricted chromosomal abnormalit y. Interphase cytogenetics, possibly using a small panel of pericentro meric probes, may be more sensitive than DNA cytometry for detecting a bnormal nuclear DNA content.