External validation of Modified Breast Graded Prognostic Assessment for breast cancer patients with brain metastases: A multicentric European experience

Abstract Background Several prognostic scores have been developed to estimate survival of breast cancer (BC) patients with brain metastases (BM). Modified Breast Graded Prognostic Assessment (GPA), based on a single-institution cohort of 1552 patients, has been proposed as refinement of Breast-GPA. In addition to age, tumour subtype and KPS, Modified Breast-GPA comprises number of BM. This study was designed to validate Modified Breast-GPA. Patients and methods Clinical data of 668 BC patients diagnosed with BM at four institutions between 1996 and 2016 were reviewed. Patients were classified by Breast-GPA and Modified Breast-GPA. Overall survival (OS) was calculated from time of BM diagnosis to death or last follow-up. Cox proportional models were used to calculate hazard-ratios and their 95% CI. The performances of Breast-GPA and Modified Breast-GPA were compared using Harrell's concordance index. Results Median age at BM diagnosis was 56 years (range 24–85). At last follow-up, 632 patients (94.6%) had died. Median OS was 8.1 months (95% CI 6.9–9.4). The number of BM (1–3 vs. >3) was significantly associated with OS in univariate analysis ( p 3 BM was identified as a negative prognostic factor in multivariate analysis. Both Breast-GPA and Modified Breast-GPA accurately predicted OS ( p p Conclusions This work provides the first external independent validation of Modified Breast-GPA and confirms its better performance as compared to Breast-GPA.