Radiotherapy utilization in BRAF mutation-tested metastatic melanoma in the targeted therapy era.

Abstract

Tumor BRAF mutation testing is routine for all patients with metastatic melanoma (MM) owing to the availability of agents targeting this intracellular pathway. To test whether there is a difference in radiotherapy (RT) utilization according to BRAF mutation status, we performed a retrospective review of RT utilization in a contemporary cohort undergoing BRAF mutation testing. Clinical records of MM patients undergoing BRAF mutation testing between April 2010 and August 2012 were reviewed. Overall survival (OS) was calculated using Kaplan-Meier methods. Differences between BRAF status were calculated using chi-square tests for categorical variables, median tests for continuous variables and Cox proportional hazards models to compare OS. Up to 158 patients were identified but 17 were excluded due to inadequate clinical data. Of the remaining 141 patients, 69 (49%) tested BRAF mutant (BRAF-m), median age 47 years (range 21-79) with median follow-up of 16.8 months (IQR11.3-25.2). Seventy-two (51%) tested BRAF wild type (BRAF-w), median age 62 years (range 25-84) with median follow-up of 27.1 months (IQR12.5-57.4). Overall, RT utilization was similar: 68% in BRAF-m and 69% in BRAF-w. Mean number of treatment courses was 1.70 for BRAF-m and 2.36 for BRAF-w (Pearson chi-square 3.92, P = 0.05). Up to 51% of BRAF-m and 56% of BRAF-w required ≧2 RT courses. Forty-six percent BRAF-m compared with 29% BRAF-w received brain RT (P = 0.04). Median OS was 17.7 months (IQR7.6-35.5) in BRAF-m and 19 months (IQR7.8-35.1) in BRAF-w (P = 0.99). High RT utilization rates were observed irrespective of BRAF mutation status. Significantly more BRAF-w patients received RT but more BRAF-m patients received brain RT.