Differential expression of cellular oncogenes in benign and malignant human breast tissue.

We have examined 62 specimens of benign fibrocystic breast tissue, fibroadenomas, carcinomas and surrounding non-malignant tissue excised from 50 patients to determine the level of expression of 4 cellular oncogenes, c-myc, c-H-ras, c-K-ras, and c-N-ras. Our results demonstrate that in breast carcinoma the frequency and relative level of expression of these oncogenes are significantly greater than those found for benign breast tissue. However, some fibrocystic specimens having prominent hyperplastic features also exhibited enhanced oncogene expression. In view of the association between the increased frequency of carcinoma of the breast in women with a previous history of benign breast disease, it will be interesting to follow up donors of benign specimens to see if there is any relationship between the expression of oncogenes in such lesions and the development of carcinomas.