273P - External validation of modified breast graded prognostic assessment for breast cancer patients with brain metastases

Abstract

Background: Several prognostic indexes have been developed to estimate survival of breast cancer (BC) patients with brain metastases (BM). The Modified Breast Graded Prognostic Assessment (GPA) has been proposed as refinement of the Breast GPA, based on a single-institution cohort of 1,552 patients. In addition to age, tumor subtype and Karnofsky PS, the modified breast GPA comprises number of BM. The aim of this study is to validate the modified breast-GPA in an external multinational cohort. Methods: Clinical and biological data of 668 BC patients diagnosed with BM at four European institutions between 1996 and 2016 were reviewed. Patients were classified according to breast GPA and modified breast GPA. OS was calculated from time of BM diagnosis to death or last follow up. Cox proportional models were used to calculate Hazard Ratio and 95% Confidence Intervals (CI). Performances of breast-GPA and modified breast-GPA were compared using Harrell's concordance index. Results: At last follow-up, 632 patients (94.6%) had died. Median OS was 8.1 months (95% CI 6.9-9.4 months). Median age at BM diagnosis was 56 years (range 24-85). Tumor phenotype distribution was: triple negative (20.1%), hormone receptor (HR)-HER2 + (21.6%), HR+HER2 + (20.4%) and HR+HER2- (33.4%). KPS distribution was: 90-100 (19.6%), 70-80 (49.0%), 60 (12.8%) and ≤50 (18.6%). 355 patients (53.5%) had >3 BM. Number of BM (1,2,3,>3) was significantly associated with OS (p < 0.001). Both breast-GPA and modified breast-GPA predicted OS (Table). Concordance indices were 0.641 (95% CI, 0.6405 to 0.6422) and 0.667 (95% CI, 0.6662 to 0.6678) for breast-GPA and modified breast-GPA, respectively (p < 0.001).Table273PBreast GPA categoryNumber of patients (%)Median OS, months (95% CI)Hazard Ratio (95% CI)p3.5-486 (13.5%)18.8 (14.5-22.6)ref<0.0012.5-3248 (38.8%)10.3 (8.8-11.8)1.45 (1.12-1.88)1.5-2194 (30.4%)6.2 (4.9-7.6)2.04 (1.56-2.66)0-1.0111 (17.4%)2.5 (1.8-3.2)4.97 (3.67-6.71)Modified breast GPA categoryNumber of patients (%)Median OS, months (95% CI)Hazard Ratio (95% CI)p3.5-437 (5.8%)18.9 (17.2-20.5)ref<0.0012.5-3209 (32.8%)15.2 (12.1-18.3)1.43 (0.98-2.09)1.5-2257 (40.3%)7.9 (5.9-9.9)2.30 (1.59-3.33)0-1.0135 (21.2%)2.3 (1.9-2.8)7.03 (4.72-10.46) Open table in a new tab Conclusions: Number of BM is a significant prognostic factor in BC patients with BM and modified breast-GPA performs better than breast-GPA in predicting prognosis of these patients. Legal entity responsible for the study: Department of Surgery, Oncology and Gastroenterology, University of Padova, Padua, Italy Funding: None Disclosure: All authors have declared no conflicts of interest.