Clinical and Therapeutic Outcomes by Molecular Subtype in Breast Cancer

Breast cancer is the most common cancer in women worldwide. Its molecular classification, based on hormone receptors (estrogen and progesterone), HER2 and Ki-67, defines subtypes with different prognoses and treatments. In Colombia, there is limited information that integrates the clinical, treatment, sociodemographic and contextual characteristics of each subtype, and limited data on the direct medical costs of breast cancer care. This retrospective cohort study will review the medical records of women 18 years or older with biopsy-confirmed breast cancer and a documented molecular subtype who were treated at Fundación Santa Fe de Bogotá (Bogotá, Colombia) between January 1, 2014 and December 31, 2024. It will describe each molecular subtype (luminal A, luminal B HER2-negative, luminal B HER2-positive, HER2-enriched, triple-negative and HER2-low) and evaluate the association of clinical, molecular and treatment characteristics with overall survival, progression-free survival, recurrence, treatment response and grade 3-4 adverse events. It will also explore the impact of the COVID-19 pandemic and health insurance regimen on outcomes, and estimate direct medical costs of breast cancer care by clinical stage and phase of care. The investigators will not assign or modify any treatment.