gms | German Medical Science

Introduction/Background: The present study was conducted to determine the effects of hormone therapy (HT) in postmenopausal women, differentiated by duration, time since last use, mode of administration as well as hormonal composition, and to assess potentially modifying factors.

Methods: The MARIE- study is a population based, two centre case-control study in the Hamburg and Rhine-Neckar-Region. The study included 3464 breast cancer cases aged 50-74 at diagnosis and 6657 controls. Data on lifetime HT were ascertained by in-person interviews using a pictogram of preparations. Logistic regression was used to estimate odds ratios (OR) and 95%-confidence intervals, stratified by year of birth and study centre and adjusted for potential confounders.

Results: Ever use of HT was associated with an increased risk of breast cancer, OR= 1.39 (1.26-1.54), whereby risk was significantly elevated in current users, OR 1.75 (1.57-1.96) but not in past users, OR=1,00 (0.89-1.34 ). Risks for current users varied significantly by type of HT, with OR=2.06 (1.79-2.38) for continuous estrogen-progestagen therapy, OR=1.80(1.50-2.15) for cyclical estrogen-progestagen therapy, and OR=1.23 (1.04-1.45) for estrogen-only therapy. In general, risks declined rapidly after one to three years since last use, except for elevated risks observed for cyclical combined therapy several years after cessation, OR=1.64 (1.32-2.05) after 5-<10 years. The effect of HT did not differ substantially by type of gestagens; risks for use of norethisterone, norgestrel, and progesterone were OR=1.71 (1.50-1.96), OR=1.69 (1.38-2.06), and OR=1.42 (1.22-1.66), respectively. Ever use of HT was not associated with increased breast cancer risks for obese women with BMI >=30.

Discussion/Conclusion: Menopause related hormone therapy was associated with an in-creased risk of breast cancer. In general, risk was most pronounced for current users and users of estrogen-progestagen therapy and decreased rapidly with time after cessation. Obesity attenuated the observed increased risks.