Individualized early death and long-term survival prediction after stereotactic radiosurgery for brain metastases of non-small cell lung cancer: Two externally validated nomograms

Abstract Introduction Commonly used clinical models for survival prediction after stereotactic radiosurgery(SRS) for brain metastases (BMs) are limited by the lack of individual risk scores and disproportionate prognosticgroups. In this study, two nomogramswere developed to overcome these limitations. Methods 495 patients with BMs of NSCLC treated with SRS for a limited number of BMs in four Dutch radiation oncology centers were identified and divided in a training cohort ( n =214, patients treated in one hospital) and an external validationcohort n =281, patients treated in three other hospitals). Using the training cohort, nomogramswere developed for prediction of early death ( 12months) with prognosticfactors for survival. Accuracy of prediction was defined as the area under the curve (AUC) by receiver operating characteristics analysis for prediction of early death and long term survival. The accuracy of the nomogramswas also tested in the external validationcohort. Results Prognosticfactors for survival were: WHO performance status, presence of extracranial metastases, age, GTV largest BM, and gender. Number of brain metastases and primary tumor control were not prognosticfactors for survival. In the external validationcohort, the nomogrampredicted early death statistically significantly better ( p versus range AUCs=0.51–0.60 respectively). With an AUC of 0.67, the other nomogrampredicted 1year survival statistically significantly better ( p p =0.34). The models are available on www.predictcancer.org. Conclusion The nomogramspredicted early death and long-term survival more accurately than commonly used prognosticscores after SRS for a limited number of BMs of NSCLC. Moreover these nomogramsenable individualized probability assessment and are easy into use in routine clinical practice.