A new prognostic index and comparison to three other indices for patients with brain metastases: an analysis of 1,960 patients in the RTOG database

Abstract

Purpose: The purpose of this study is to introduce a new prognostic index for patients with brain metastases and compare it with three published indices. Treatment for brain metastases varies widely. A sound prognostic index is thus important to guide both clinical decision making and outcomes research.

Methods and materials: A new index was developed because of limitations in the three existing indices and new data (Radiation Therapy Oncology Group 9508) are available since the others were developed. All four indices were compared using the Radiation Therapy Oncology Group database of 1,960 patients with brain metastases from five randomized trials. The ability of the four indices to distinguish its separate classes was determined statistically. Advantages and disadvantages of each index are discussed.

Results: Recursive partitioning analysis (RPA) and the new Graded Prognostic Assessment (GPA) had the most statistically significant differences between classes (p < 0.001 for all classes).

Conclusions: The new index, the GPA, is as prognostic as the RPA and more prognostic than the other indices. The GPA is the least subjective, most quantitative and easiest to use of the four indices. Future clinical trials should compare the GPA with the RPA to prospectively validate these findings.