Hormonal contraceptives and molecular subtypes of breast cancer: A cross-sectional study in a Peruvian oncology institute

Introduction Breast cancer remains a major global health concern, with incidence, risk factors, and diagnostic challenges differing across regions. In Latin America, further research is needed to clarify the influence of hormonal contraceptives on specific molecular subtypes. Objective To assess the association between hormonal contraceptive use and molecular subtypes of breast cancer among patients treated at a specialized oncology center in Lima, Peru. Methods A cross-sectional study was conducted at the Instituto Nacional de Enfermedades Neoplásicas (INEN) between 2024 and 2025, including 269 women with histologically confirmed breast cancer who had undergone surgery. Data were obtained through structured interviews and a review of medical records. Associations between hormonal contraceptive use and clinical, reproductive, histopathological variables, and molecular subtypes were analyzed using Poisson regression to estimate unadjusted and adjusted prevalence ratios. Results Luminal subtypes accounted for 62.8% of cases, with Luminal B being the most common (48.7%). Overall, 53.5% of participants reported hormonal contraceptive use for 2–8.5 years, predominantly combined estrogen–progestin formulations (63.1%). No statistically significant association was found between hormonal contraceptive use and molecular subtypes. Conclusion No significant association was identified between hormonal contraceptive use and breast cancer molecular subtypes, although several clinical, reproductive and histopathological factors were significantly associated with luminal and non-luminal subtypes.