Identification of risk factors for central nervous system metastasis in patients with breast cancer with neurologic symptoms

Background: The current study was performed to identify factors that are present at the time of breast cancer (BC) diagnosis that are associated with a higher rate of central nervous system metastasis (CNSm). Methods: The authors analyzed a database of patients with a confirmed diagnosis of BC who were referred for a neuro-oncology consultation at the National Cancer Institute in Mexico City, Mexico, from June 2009 to June 2017. Information was collected prospectively and included demographic, pathologic, and clinical data at the time of diagnosis of BC. Bivariate and multivariate logistic regression models were built to estimate the associations between the development of CNSm and the time after BC diagnosis. Results: Among 970 patients with BC, 263 (27%) were diagnosed with CNSm. The median time from BC diagnosis to the development of CNSm was 33 months (interquartile range, 15-76 months). After multivariate analysis, age <50 years at the time of BC diagnosis (odds ratio [OR], 2.5; 95% confidence interval [95% CI], 1.8-3.5 [P <.0001]), human epidermal growth factor receptor 2 (HER2)–positive status (HER2+) (OR, 3.6; 95% CI, 2.1-6.1 [P <.0001]), luminal B/HER2+ subtype (OR, 3.1; 95% CI, 1.9-5.3 [P <.001]), triple-negative subtype(OR, 2.4; 95% CI, 1.5-4 [P =.001]), and Karnofsky performance status ≤70 (OR, 6.6; 95% CI, 4.5-9.6 [P <.0001]) were associated with a higher frequency of CNSm. Brain parenchyma was the most common site of CNSm. The median overall survival after a diagnosis of CNSm was 12.2 months (95% CI, 9.3-15.1 months). Conclusions: CNSm is not uncommon among patients with BC, particularly in those with neurologic symptoms who require neuro-oncology evaluation and are aged <50 years at the time of diagnosis, have HER2+ or triple-negative subtypes, have a poor Karnofsky performance status, and/or have ≥2 non-CNS metastases.