Prediction of outcomes for patients with brain parenchymal metastases from breast cancer (BC): a new BC-specific prognostic model and a nomogram

Abstract

The purpose of this study is to validate the recently published Breast-Graded Prognostic Assessment (GPA) and propose a new prognostic model and nomogram for patients with brain parenchymal metastases (BM) from breast cancer (BC). We retrospectively investigated 171 consecutive patients who received a diagnosis of BM from BC during 2000-2008. We appraised the recently proposed Sperduto's BC-specific GPA in training cohort through Kaplan-Meier survival curve using log-rank test and area under the curve for the BC-GPA predicting overall survival at 1 year and developed a new nomogram to predict outcomes using multivariate Cox-regression analysis. By putting the Sperduto's Breast-GPA together with our nomogram, we developed a new prognostic model. We validated our new prognostic model with an independent external patient cohort from 2 institutes for the same period. On the basis of our Cox-regression analysis, therapeutic effect of trastuzumab and status of extracranial systemic disease control were incorporated into our new prognostic model in addition to Karnofsky performance status, age, and hormonal status. Our new prognostic model showed significant discrimination in median survival time, with 3.7 months for class I (n = 15), 7.8 months for class II (n = 82), 10.7 months for class III (n = 42), and 19.2 months for class IV (n = 32; P < .0001). The new prognostic model accurately predicted survival among patients with BC from BM in an external validation cohort (P < .0001). We propose a new prognostic model and a nomogram reflecting the different biological features of BC, including treatment effect and status of extracranial disease control, which was excellently validated in an independent external cohort.