Outcomes from 735 patients with breast cancer brain metastases (BM) according to biological subtype, number of BMs, and systemic treatment after local therapy.

Abstract

2078 Background: To assess survival when BM is detected according to the biological subtype of breast cancer, number of BMs and systemic treatment after local therapy. Methods: Subjects were 735 consecutive breast cancer patients with BM treated during 2003-2015. Whole brain radiotherapy was undertaken in 97%, neurosurgery -19% and systemic therapy was performed in 74% cases. The biological subtypes: triple-negative (TNBC), HER2+ER/PR-, HER2+/ER/PR+ and ER/PR+HER2- (Luminal) were determined in 714 subjects. Survival after BM detection was assessed in the entire group, in patients with a single BM (1 brain lesion regardless of metastases in other organs) and those with a solitary brain metastasis (1 brain lesion but no metastases in other organs). Factors influencing survival upon detecting BM were assessed by Cox multivariate analysis. Results: The median survivals for all patients with TNBC, HER2+ER/PR-, HER2+/ER/PR+ and Luminal breast cancer BM were respectively 4, 8, 10 and 9 months (p < 0.001). In those both treated and untreated systemically within the TNBC, HER2+ER/PR-, HER2+/ER/PR+ and Luminal subtypes survivals were correspondingly 6, 10, 14, 11 and 2, 3, 2, 2 months (p < 0.001). Median survivals of 171 patients with a single BM treated and untreated systemically were respectively 15 and 5 months (p < 0.001). Median survivals of 70 patients with solitary BM treated and untreated systemically were respectively 28 and 6 months (p < 0.001). In patients with solitary brain metastasis, median survival within the TNBC, HER2+ER/PR-, HER2+/ER/PR+ and Luminal subtypes, with systemic treatment was respectively 16, 28, 28, 28 months and without systemic treatment 6, 7, 7 and 7 months (p < 0.001). Conclusions: Patients with TNBC and BM had the worst prognosis. Systemic treatment performed after local therapy is an important factor prolonging survival of patients with breast cancer BM, even in those with solitary brain metastasis. Based on the present evidence and our recent publication, systemic treatment should be performed in all patients with BM after local treatment, even those with brain metastases as an isolated recurrence.