BRAF Mutation Correlates with Worse Local-regional Control Following Radiation Therapy in Patients with Stage III Melanoma
Background In patients with stage III melanoma, the use of adjuvant radiation therapy (RT) after lymph node dissection (LND) may be currently considered in selected high-risk patients to improve local-regional control. Melanomas harbor BRAF mutations (BRAF+) in 40–50% of cases, the majority of which are on the V600E residue. This study sought to compare the clinical outcomes after RT between patients with BRAF + and BRAF- melanoma. Methods This was a retrospective review of 105 Stage III
... 05 Stage III melanoma patients treated at our institution with LND followed by adjuvant RT from 2006–2019. BRAF mutational status was determined on the primary skin or nodal tissue samples from all patients. We compared characteristics of the BRAF + and BRAF- groups using Fisher's exact test and Wilcoxon rank sum test and performed univariate and multivariate analysis using Kaplan-Meier estimates, log-rank tests, and Cox proportional hazards modeling with the clinical outcomes of local-regional control (LRC), distant metastasis-free survival (DMFS), disease-free survival (DFS), and overall survival (OS). Results Fifty-three (50%) patients harbored a BRAF mutation (92%, pV600E). BRAF + patients were younger and had primary tumors more commonly found in the trunk vs head and neck compared to BRAF- patients (p < 0.05). The 5 year local-regional control in the BRAF + patients was 60% compared to 81% in the BRAF- patients (HR 4.5, 95% CI 1.3–15.5, p = 0.02). There were no significant differences in 5-year DMFS, DFS, and OS rates between the two BRAF patient groups. The presence of 4 or more positive LNs remained a significant prognostic factor for LRC, DFS, and OS in multivariate analysis. Conclusions Stage III melanoma patients with BRAF mutation treated with adjuvant RT had > 4 times increased risk of loco-regional recurrence. These results could be useful for adjuvant RT consideration in lymph node positive melanoma patients and supports other data that BRAF mutation confers radiation resistance.