In Reply to Drs. Weltman and Brandt

Abstract

To the Editor: We thank Dr. Weltman for his thoughtful comments regarding our article, “A new prognostic index and comparison to three other indexes for patients with brain metastases: an analysis of 1,960 patients in the RTOG database” ( 1 Sperduto P.W. Berkey B. Gaspar L.E. et al. A new prognostic index and comparison to three other indexes for patients with brain metastases: An analysis of 1,960 patients in the RTOG database. Int J Radiat Oncol Biol Phys. 2008; 70: 510-514 Abstract Full Text Full Text PDF PubMed Scopus (732) Google Scholar ). We commend him for his contributions to our discipline in this area but respectfully disagree with many of his assertions, as follows. His primary concern is that only 12% (244 patients) of the Radiation Therapy Oncology Group database (1,960 patients) could be scored on the Score Index for Radiosurgery (SIR). We respectfully point out that the 244 SIR-scored patients far exceeds the 65 patients on whom the SIR was originally described ( 2 Weltman E. Salvajoli J.V. Brandt R.A. et al. Radiosurgery for brain metastases: A score index for predicting prognosis. Int J Radiat Oncol Biol Phys. 2000; 46: 1155-1161 Abstract Full Text Full Text PDF PubMed Scopus (307) Google Scholar ) and thus is a better test of that index than the original report. Second, Dr. Weltman argues that the clinical and radiologic data obtained during follow-up are uniform. We have observed that, outside of a clinical trial, the variation in the type, timing, and completeness of follow-up studies is wide. This injects a vast potential for error when comparing outcomes. For this reason, our proposed prognostic index, the Graded Prognostic Assessment (GPA), uses only whether extracranial metastases are present or absent at the time of the diagnosis of the brain metastases. For widespread acceptance and application, a prognostic index must be simple and easy to apply. The ease of application is another advantage of the GPA over recursive partitioning analysis ( 3 Gaspar L. Scott C. Rotman M. et al. Recursive partitioning analysis (RPA) of prognostic factors in three Radiation Therapy Oncology Group (RTOG) trials. Int J Radiat Oncol Biol Phys. 1997; 37: 745-751 Abstract Full Text PDF PubMed Scopus (2009) Google Scholar ), the Basic Score for Brain Metastases (BSBM) ( 4 Lorenzoni J. Devriendt D. Massager N. et al. Radiosurgery for treatment of brain metastases: Estimation of patient eligibility using three stratification systems. Int J Radiat Oncol Biol Phys. 2004; 60: 218-224 Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar ), and the SIR. In Regard to Sperduto et al. (Int J Radiat Oncol Biol Phys 2008;70:510–514)International Journal of Radiation Oncology, Biology, PhysicsVol. 70Issue 4PreviewTo the Editor: The article “A new prognostic index and comparison to three other indexes for patients with brain metastases: an analysis of 1,960 patients in the RTOG database” by Sperduto et al.(1) has some debatable points regarding their comments to the Score Index for Stereotactic Radiosurgery (SIR) for Brain Metastases. (2). The strongest one is that only 12% of the accrual could be staged by the SIR. In this scenario, the statistical analyses could not be adequately addressed. To compare the accuracy of these indexes, it will be necessary to analyze an equivalent number of patients. Full-Text PDF