Aim: Hormone replacement therapy (HRT) is widely used by post-menopausal women. Although this treatment may slightly increase the incidence of breast cancer, more and more cases are diagnosed while women are taking HRT. The purpose of this study was to ascertain the influence of HRT on prognostic factors and outcome of breast cancer. Data on all breast cancer patients, including precise information on HRT, was prospectively and systematically recorded in a data base.
Patients and methods: From 1990 to 1998, 1223 post-menopausal women fulfilled the eligibility criteria for this study. The clinical features, laboratory findings and survival rates in 245 HRT users who developed breast cancer while being treated were compared with those of 245 matched breast cancer patients who had never received HRT.
Results: Patients who developed breast cancer during HRT had fewer locally advanced cancers and smaller and better-differentiated cancers. Estradiol receptivity was quantitatively lower in users. Metastasis-free survival were better for the users.
Conclusion: We conclude that HRT does not affect the prognosis of breast cancer. Regular surveillance during HRT allows early detection of smaller lesions. The higher number of well-differentiated cancers and the distribution of hormone receptivity may reflect interaction between neoplastic tissue and exogenous hormones.