INTERPHASE CYTOGENETICS IN MAMMOGRAPHICALLY DETECTED BREAST-LESIONS

Chromosomal aneuploidy in 25 mammographically detected breast lesions (MDBL) were determined on cytological smears using directly labeled pe ricentromeric probes for chromosomes 7 to 12, 17, 18, and X. The lesio ns included seven nonproliferative (NP) lesions, seven atypical hyperp lasias (AHs), and 11 carcinomas (CAs). No other significant histologic al findings were identified in the remaining specimens except in two m ammographically detected NP lesions, where foci of AH were present in adjacent sections; therefore, these two specimens were included in the AH lesion group (moderately increased risk lesions). Corresponding ti ssue sections were evaluated, and the results were correlated with flu orescent in situ hybridization (FISH) results. Monosomy was defined as the loss of one signal in greater than or equal to 15% of cells, and trisomy or tetrasomy was defined by the presence of three or more sign als in greater than or equal to 3% of cells. Chromosomal aberrations w ere detected in 2 of 5 NP, 9 of 9 AH, and 11 of 11 CA groups. The mean number of cells with three or more signals, for all chromosomes, was 1.04 +/- 0.9 in the NP group, 8.5 +/- 9.4 in the AH group, and 20.2 +/ - 5.4 in the CAs. A significant statistical difference was noted betwe en the different groups (P = .0001). Chromosomal gain was the most com mon aberration and involved all chromosomes. The X chromosome was the only individual chromosome with significant differences in NP, AH, and CA groups. Chromosomal loss was observed in five specimens (20%) and involved chromosomes 8, 10, 17, and 18. The authors conclude (1) signi ficant chromosomal aberrations can be detected in AH lesions and in NP epithelium from patients with moderately increased risk lesions; (2) numerical chromosomal aberrations tend to increase with progression of disease; (3) the frequent chromosomal gains/losses involving AH sugge st that some AH may display submicroscopic features of malignancy; and (4) combined chromosomal aberrations allow for significant categoriza tion of breast lesions, especially in cytology specimens. (C) 1996 by W.B. Saunders Company