Estrogen replacement therapy for menopausal women with a history of breast carcinoma: results of a 5-year, prospective study

Background: Women with a history of breast carcinoma generally have been advised to avoid estrogen replacement therapy (ERT). The validity of this approach has been scrutinized and debated in recent years, and reassessment through appropriate clinical trials has been suggested.

Methods: The authors conducted a prospective clinical trial to assess the safety and efficacy of prolonged ERT in a group of menopausal women with localized (Stage I or Stage II) breast carcinoma and a minimum disease free interval of 2 years if estrogen receptor (ER) was negative or 10 years if ER status was unknown. For 5 years, the authors followed 77 trial participants and 222 other women with clinical and prognostic characteristics comparable to those of the trial participants. Overall, 56 women were on ERT, and 243 women were not on ERT. The association of ERT with skeletal and lipid changes was assessed in the randomized trial participants. The effect of ERT on the development of recurrent or new breast carcinoma and other carcinomas was analyzed both in the trial participants and in the overall group.

Results: Patient and disease characteristics, such as tumor size, number of lymph nodes involved, ER status, menopausal status, and disease free interval were comparable for women who were on ERT and women who were not on ERT. These same parameters also were comparable for women who joined the trial and women who did not. ERT use was associated with modest lipid and skeletal benefits. The introduction of ERT did not compromise disease free survival. Two of 56 women on ERT (3.6%) developed a contralateral, new breast carcinoma. In the group that was not on ERT, 33 of 243 women (13.5%) developed new or recurrent breast carcinoma. There were no differences in the development of other carcinomas with respect to ERT.

Conclusions: ERT did not compromise disease free survival in select patients who were treated previously for localized breast carcinoma. Larger scale randomized trials are needed to confirm these findings.