RMTC-04 RISK FACTORS ASSOCIATED WITH EARLY BRAIN METASTASES IN BREAST CANCER: A RETROSPECTIVE COHORT STUDY FROM A SPECIALIZED CANCER CENTER IN CENTRAL AMERICA

Abstract

Breast cancer (BC) is the most common malignancy among women and the second most common cause of brain metastases (BM). The development of BM significantly affects survival and quality of life in these patients. Despite advances in imaging and systemic therapies, outcomes remain poor and early detection continues to be challenging. Identifying factors associated with early BM may help define high-risk patients and improve surveillance strategies. This study aimed to identify factors associated with early BM in patients with BC treated at a specialized cancer center in Central America. A retrospective analytical cohort study was conducted including female patients aged ≥18 years with histologically confirmed invasive BC who developed BM between January 2019 and December 2023. Patients were classified according to the interval between BC diagnosis and BM development: early BM (≤24 months) and late BM (>24 months). Variables were obtained from electronic medical records. Descriptive statistics and comparative analyses were performed using the chi-square or Fisher’s exact test, and relative risks with 95% confidence intervals were calculated. A total of 112 patients were included; 63 (56.3%) developed early BM and 49 (43.7%) developed late BM. HER2-positive IHC 3+ and triple-negative subtypes were significantly more frequent in the early BM group, while luminal A tumors were more common in late BM cases (RR = 2.74, 95% CI 1.41–5.33, p < 0.001). Patients with early BM more frequently presented with advanced clinical stages (III–IV) at diagnosis. The median time to BM development was 14 months in the early group and 41 months in the late group (p < 0.001). Early development of BM in BC is strongly associated with tumor biology, particularly HER2-positive IHC 3+ and triple-negative subtypes, as well as advanced stage at diagnosis. These findings support risk-adapted neurological surveillance strategies in patients with this profile.