The influence of postoperative lymph node radiation therapy on overall survival of patients with stage III melanoma, a National Cancer Database analysis.

Abstract

Recently, TROG 02.01 results showed that in stage III melanoma patients with nodal metastasis, adjuvant radiation to lymph node basin after nodal dissection improves lymph node field relapse without an overall survival (OS) benefit. However, this trial was neither designed nor powered to detect an OS difference. In the present study, we analyzed patients in the National Cancer Database (NCDB) with stage III melanoma with pathologically involved nodes and compared survival outcomes of adjuvant radiation and no-radiation cohorts. Inclusion criteria were as follows: age at least 18 years; diagnosed 2003-2011; surgery to regional lymph nodes; pathologically involved lymph nodes; and American Joint Committee on Cancer stage (IIIA-C). We used propensity score matching analysis to compare the OS of patients with similar baseline demographic, clinical, and pathologic characteristics who received adjuvant radiation and no adjuvant radiation. Overall, 912 patients were analyzed with an average age at diagnosis of 54.4 years and a median follow-up time of 5.5 years. In this cohort, the 5-year OS was 69.0, 51.1, and 30.6% for stage IIIA, IIIB, and IIIC, respectively. On propensity score-adjusted multivariate analysis, we found that adjuvant radiation had no statistically significant impact on OS (hazard ratio: 1.09, 95% confidence interval: 0.75-1.58, P=0.640). Furthermore, age older than 60 years, number of nodes, increasing pathologic stage, and absence of immunotherapy correlated with worse OS. In this NCDB analysis, we found that the adjuvant radiotherapy for node-positive, stage III melanoma patients did not improve OS. This is consistent with TROG 02.01; however, there may be patient selection bias not accounted for by the NCDB.