1079 Background: Brain metastases (BM) are a common and fatal complication of breast cancer but survival varies widely based on various prognostic factors (PF). Hence, patient counseling and therapeutic decisions should be individualized. We previously published a prognostic index (Breast GPA) based on cohort A (1985-2007, n = 642), updated it with tumor subtype in cohort B (1993-2010, n = 400) and are now updating it with a larger contemporary cohort (C). Methods: A multi-institutional (19) multi-national (3) retrospective database of 2473 breast cancer patients with BM diagnosed from 1/1/2006-12/31/2017 was created and compared to our prior cohorts. Demographic, clinical, molecular factors, tumor subtype and treatment were correlated with survival. Kaplan-Meier survival estimates were calculated and compared with log-rank tests. Results: The median survival (MS) for cohorts A, B and C improved over time [12, 14 and 16 mo, respectively ( < 0.01)] despite the subtype distribution becoming less favorable: Luminal B (ER/PR/HER2+) decreased from 26% to 21%; HER2 (HER2+/ER/PR-) decreased from 31% to 17%, Luminal A (ER/PR+/HER2-) increased from 20% to 31%; Basal (ER/PR/HER2-) was unchanged at 24%.MS by subtype improved from 21 to 27 mo in Luminal B, 18 to 25 mo in HER2, 10 to 14 mo in Luminal A and 6 to 9 mo in Basal tumors. The number of BM was 1 in 35%, ≤4 in 67% and > 10 in 18%. PF significant for survival were tumor subtype, age, KPS, number of BM and extracranial metastases (ECM) (all < 0.01). Surprisingly, Hispanic women (7%) showed improved survival (p < 0.01). BRCA1 was mutated in 57/533 (11%) and those patients showed a trend (0.16) toward improved survival. Treatment patterns have changed: the use of whole brain radiation therapy decreased from 71% to 67% to 47% in cohorts A, B and C, respectively. Conclusions: Despite the shift to less favorable tumor subtypes, MS has improvedbut varies widely by diagnosis-specific PF. Compared to prior cohorts, number of BM and ECM were identified as new PF. Ethnic, genetic and treatment differences between the eras are apparent. The updated Breast GPA, based on these data, and the correlation between BRCA1 and tumor subtype will be presented.
PO101 PROGNOSTIC FACTORS AFTER GAMMA KNIFE RADIOSURGERY IN BREAST CANCER PATIENTS WITH BRAIN METASTASES
