Stereotactic radiosurgery results for brain metastasis patients with renal cancer: A validity study of Renal Graded Prognostic Assessment and proposal of a new grading index (JLGK2101 Study)

Background and purpose: The Renal Graded Prognostic Assessment (GPA) is relatively new and has not been sufficiently validated using a different dataset. We thus developed a new grading index, the Renal Brain Metastasis Score (Renal-BMS). Materials and methods: Using our dataset including 262 renal cancer patients with brain metastases (BMs) undergoing stereotactic radiosurgery (SRS) (test series), we validity tested the Renal-GPA. Next, we applied clinical factor-survival analysis to the test series and thereby developed the Renal-BMS. This system was then validated using another series of 352 patients independently undergoing SRS at nine gamma knife facilities in Japan (verification series). Results: Using the test series, with the Renal-GPA, 95% confidence intervals (CIs) of the post-SRS median survival times (MSTs) overlapped between pairs of neighboring subgroups. Among various pre-SRS clinical factors of the test series, six were highly associated with overall survival. Therefore, we assigned scores for six factors, i.e., KPS >= 80%/<80% (0/3), tumor numbers 1-4/>= 5 (score; 0/2), controlled primary cancer/not (0/2), existing extra-cerebral metastases/not (0/3), blood hemoglobin >= 11.0/<11.0 g/dl (0/1) and interval from primary cancer to SRS >= 5/<5 years (0/1). Patients were categorized into three subgroups according to the sum of scores, i.e., 0-4, 5-8 and 9-12. In the test and verification series, post-SRS MSTs differed significantly (p < 0.0001) with no overlaps of 95% CIs among the three subgroups. Conclusions: The Renal BMS has the potential to be very useful to physicians selecting among aggressive treatment modalities for renal cancer patients with BMs.

Automated summary

This study aimed to develop a new scoring index, the Renal Brain Metastasis Score (Renal-BMS), to assess the risk associated with treatment selection for renal cancer patients. Through clinical factor-survival analysis and validation series, it was found that Renal-BMS can clearly differentiate the survival time of patients among different subgroups.