Prognostic factors and survival according to tumour subtype in women presenting with breast cancer brain metastases at initial diagnosis

Abstract

Background: The presence of brain metastases at the time of initial breast cancer diagnosis (BMIBCD) is uncommon. Hence, the prognostic assessment and management of these patients is very challenging. The aim of this study was to analyse the influence of tumour subtype compared with other prognostic factors in the survival of patients with BMIBCD.

Methods: We evaluated women with BMIBCD, reported to Surveillance, Epidemiology and End Results program from 2010 to 2013. Patients with other primary malignancy were excluded. Univariate and multivariate analyses were performed to determine the effects of each variable on overall survival (OS).

Results: We included 740 patients. Median OS for the whole population was 10 months, and 20.7% of patients were alive at 36 months. Tumour subtype distribution was: 46.6% hormone receptor (HR)+/HER2-, 17% HR+/HER2+, 14.1% HR-/HER2+ and 22.3% triple-negative. Univariate analysis showed that the presence of liver metastases, lung metastases and triple-negative patients (median OS 6 months) had worse prognosis. The HR+/HER2+ subtype had the longest OS with a median of 22 months. In multivariate analysis, older age (hazard ratio 1.8), lobular histology (hazard ratio 2.08), triple-negative subtype (hazard ratio 2.25), liver metastases (hazard ratio 1.6) and unmarried patients (hazard ratio 1.39) had significantly shorter OS.

Conclusions: Although the prognosis of patients with BMIBCD is generally poor, 20.7% were still alive 3 years after the diagnosis. There were substantial differences in OS according to tumour subtype. In addition to tumour subtype, other independent predictors of OS are age at diagnosis, marital status, histology and liver metastases.

Keywords: Brain metastases; Breast cancer; HER2; Oestrogen receptor; Progesterone receptor; Prognostic factors; Tumour subtypes.