A specific nomogram to predict subsequent brain metastasis in metastatic triple-negative breast cancer patients

Abstract

1028 Background: The development of brain metastases is usually a fatal event in the history of breast cancer patients with metastatic disease other than brain (MDOB). We previously developed a global nomogram that includes immune-histochemical phenotype to predict the occurrence of brain metastasis (BM). We hypothesized that a nomogram specific to triple negative tumor (TN) could improve prediction BM occurrence in patients with MDOB, thus allowing allocation of preventive treatment more efficiently. Methods: Patients with metastatic BC presenting between 2000 and February 2007 treated at M. D. Anderson Cancer Center were included in this retrospective analysis. We tested 17 variables and developed a multivariate model to predict occurrence of subsequent BM in TN tumors and created a nomogram that could be used for individual prediction. The model was cross-validated by bootstrapping and compared to the global nomogram. Results: Among 2,136 patients with metastatic breast cancer including 641 patients with TN tumors, 362 developed BM during follow-up: young age, histological characteristics, short delay between initial diagnosis and MDOB, number of metastatic sites and initial number of metastatic nodes were significantly and independently associated with subsequent BM. The nomogram to predict BM developed on the TN population provided a better discrimination (area under the ROC curve [AUC] = 0.62) than the global nomogram (AUC = 0.58) for the TN tumors. Prediction with the specific nomogram and the global nomogram were highly correlated (correlation factor = 0.67, p < 0.0001). However, when a threshold at 15% was used, we observed 27% of discordant cases and the sensitivity of the specific nomogram was better. Conclusions: We developed a specific tool to predict subsequent BM in patients with metastatic TN breast cancer. This nomogram outperformed a global nomogram. No significant financial relationships to disclose.