Intensity-modulated radiation therapy for patients with 1 to 3 brain metastases in recursive partitioning analysis class 3
The prognosis is extremely poor for patients with brain metastases in recursive partitioning analysis (RPA) class 3. It is not clear whether dose elevation for brain lesions in addition to whole-brain radiotherapy could improve survival for those patients. This study aimed to assess the efficacy and safety of dose elevation with intensity-modulated radiation therapy (IMRT) for patients with 1 to 3 brain metastases in RPA class 3.
From January 2013 to December 2015, 24 patients with 1 to 3 brain metastases in RPA class 3 were included in this study. The median age was 60 (range 41–85) years and the mean graded prognostic assessment (GPA) score was 1.25 (range 0.5–2). Whole-brain radiotherapy (30 Gy) with a simultaneous integrated boost (SIB) to the brain metastases (totaling 40 Gy) was delivered in 10 fractions using IMRT technique. Survival times and overall safety were assessed. The significance of prognostic variables on survival was assessed by both univariate and multivariate analyses.
All of the patients completed the planned SIB schedule. The overall response rate was 66.7%. The median survival time (MST) was 8 months for the entire group of patients. The MST was 5 months for patients with a GPA score of 0.5 to 1 (n = 11 patients) and 12 months with a GPA score of 1.5 to 2 (n = 13 patients). No acute or late toxicities greater than grade 2 were detected. Age and subsequent chemotherapy were significantly associated with MST on univariate and multivariate analyses.
It is feasible to elevate radiation doses to 40 Gy using the IMRT technique in RPA class 3 patients with 1 to 3 brain metastases without serious toxicities. The preliminary results are encouraging and further studies with larger cohorts are warranted.