Progestagen-only treatment before menopause: increased risk of breast cancer

(1) A prospective cohort study (E3N) conducted in France included approximately 100 000 women aged 40 to 64 years who were regularly questioned about their use of hormone and other treatments. More than 70 000 of the 100 000 women responded to the questionnaire. The study showed an increase in breast cancer among women using an oral progestagen alone for more than 4.5 years before menopause (low-dose progestagens were excluded from the study); (2) The risk of developing breast cancer was approximately 1.5 times higher than among women who had not taken progestagen. After progestagen discontinuation, regardless of treatment duration, the risk of breast cancer dropped to levels similar to those of non-users; (3) There is widespread use of progestagen-only products before menopause in spite of the lack of robust evidence concerning their risk-benefit balance, particularly with long-term treatment. It is advisable to evaluate drugs before their use provokes adverse reactions in patients.