Adherence with hormonal therapy in women with breast cancer: a cross-sectional study in Medellin, Colombia.

Background: Although hormone therapy is a cornerstone in the treatment of breast cancer, low therapeutic adherence is commonly reported, and there is limited evidence on the predictors that contributes to improving adherence in this population. Objective: To identify factors associated with adherence to hormone therapy in women with breast cancer, in an oncology clinic in Medellín-Colombia (2019- 2023). Methods: Cross-sectional analytical study. Women >18 years old with hormone receptor-positive breast cancer who were undergoing hormone therapy were included. The MMAS-8 scale was used to measure and classify therapeutic adherence into three levels: low, medium, and high. Data was analyzed by multinomial logistic regression. Results: One hundred seventy-eight patients with a median age of 64.0 years were included. 50.0% were treated with tamoxifen. The prevalence of non-adherence was 48.9%. 70.2% had adverse effects of hormone therapy, and forgetfulness was the main reason for discontinuation (76.19%). Age was associated with therapeutic adherence, with older women being the most adherent (83.5%). Women with adverse effects, stage III-IV, low socioeconomic and educational level, and a lack of support network had lower therapeutic adherence. Conclusions: A high prevalence of moderate and low therapeutic adherence is demonstrated in younger women from lower socioeconomic and educational backgrounds. Preventive strategies are needed to mitigate factors that negatively influence therapeutic adherence.