Objectives: To determine any association between hormonal replacement therapy (HRT) usage and breast cancer recurrence and survival rates in women who were premenopausal at the time of diagnosis of breast cancer.
Methods: The study group comprised 524 women who were diagnosed with breast cancer when they were premenopausal. Of these, 277 women reached menopause before recurrence of the disease, being lost to follow-up, or reaching the end of the study. In this group, 119 women took HRT to control menopausal symptoms. The majority took combined continuous estrogen-progestin treatment. Times from diagnosis to cancer recurrence or new breast cancer, to death from all causes, and to death from primary tumor were compared between HRT users and non-users.
Results: Women who used HRT after their menopause had an adjusted relative risk of recurrence or new breast cancer of 0.75 (95% confidence interval (CI), 0.29-1.95) compared to that of non-users. The relative risk of death from all causes was 0.36 (95% CI, 0.11-1.16) and that of death from primary tumor was 0.24 (95% CI, 0.05-1.14).
Conclusion: HRT use in women who were premenopausal at the diagnosis of primary invasive breast cancer is not associated with worse outcomes in terms of breast cancer recurrence or mortality.