Hormone replacement therapy and the risk of breast lesions that predispose to cancer.

To determine whether postmenopausal individuals being treated with hormone replacement therapy (HRT) have an increased risk for lesions that predispose to breast cancer, 156 women with benign breast lesions were retrospectively studied. Their ages ranged from 43 to 88. Each patient underwent a breast biopsy from 1991 to 1995. It was determined from chart review whether each of these patients had been treated with HRT. Fifty-seven of these patients had a biopsy finding that predisposed the patient to future breast cancer. The predisposing lesions included sclerosing adenosis, intraductal papilloma, and epithelial hyperplasia with atypia. Of these 57 patients, 36 (63%) were being treated with HRT. Only 30 of the 99 patients (30%) with nonproliferative lesions were treated with HRT (odds ratio, 3.9; P < 0.0005). On the basis of the results of this study, we believe that the use of HRT may promote lesions that predispose to cancer. This suggests that patients treated with HRT require vigilant surveillance by way of examination and mammography.