The effects of hormone replacement therapy on postmenopausal breast cancer biology and survival

BACKGROUND: The goal of this study was to compare the characteristics of breast cancers and survival rates in HRT users versus nonusers. METHODS: Data were analyzed for 1055 patients 2:50 years of age who had definitive therapy for breast cancer from 1994 through 2002. RESULTS: There were 471 (45%) HRT users. The median age at diagnosis wits 61.0 years for HRT users and 68.0 years for HRT nonusers (P < .001). HRT users more often had tumors that were < 1 cm (P = .007), node negative (P = .033), and grade I (P = .016). HRT users had a decreased risk of death versus nonusers (hazard ratio = .438, 95% confidence limit = .263 to .729, P = .002). CONCLUSIONS: HRT users developed breast cancer at a younger age than nonusers; HRT use was associated with the development of biologically more favorable cancers than those that developed in nonusers; and overall and disease-free survival rates were higher in HRT users than nonusers. (c) 2009 Published by Elsevier Inc.