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

Aim: 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. Methods: 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. Results: 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). Conclusion: 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.