Re-evaluating desogestrel: hormonal contraception, early-onset breast cancer, and the postpartum period.

This clinical perspective evaluates the implications of recent registry-based findings that associate desogestrel-containing hormonal contraceptives with early-onset breast cancer, considering potential modifications to clinical practice. The analysis focused on cancers diagnosed before age 50 that are significantly shaped by the epidemiology of early-onset breast cancer, the transient postpartum increased risk of breast cancer, genetic susceptibility, and the clinical selection of progestin-only methods for women with cardiometabolic risk. Associations observed with desogestrel may reflect residual confounding from postpartum timing, breastfeeding duration, and metabolic factors, rather than drug-specific carcinogenicity. Due to the many drawbacks of the registry study, the current evidence does not support discouraging the use of desogestrel during lactation or in patients contraindicated for oestrogen, de facto depriving many women of the possibility to perform an appropriate hormonal contraception. This paper delineates methodological priorities for future research to effectively distinguish biological effects from reproductive and metabolic confounding factors.