A graded prognostic model for patients surviving 3 years or more (GPM≥3Ys) after stereotactic radiosurgery for brain metastasis.

Abstract Background and purpose As more cancer patients with brain metastases (BMs) are surviving longer due to recent advancements in various treatment modalities, we developed a grading system for stereotactic radiosurgery (SRS)-treated BM patients with long survival. This is a Graded Prognostic Model for Patients Surviving 3 Years or More (GPM≥3Ys). Materials and methods First, using clinical factor-survival time analysis of 3237 patients in whom gamma knife (GK) SRS was performed by the second author (test cohort), we developed the GPM≥3Ys based on survival ≥3 years as the objective variable. The validity of this model was then tested using another series of 3317 patients independently undergoing GK SRS performed by the third author (verification cohort). Number of patients surviving 3 years or more were 289 (8.9%) and 348 (10.5%), respectively. Results Using the Y-series, among various pre-SRS clinical factors, noted below, five were shown to be highly correlated with survival of ≥3 years. Therefore, we assigned scores for these five factors, i.e., “tumor numbers 1/2-4/≥5 (score; 6/1/0)”, “female/male (5/0)”, “KPS ≥80%/ Conclusion Although this was a retrospective study, the GPM≥3Ys system was shown to be very useful to physicians selecting among more aggressive treatment modalities for patients in whom longer survival can be expected.