The benefits of adjuvant radiation therapy after therapeutic lymphadenectomy for clinically advanced, high-risk, lymph node-metastatic melanoma

BACKGROUND: The objective of this study was to evaluate the impact of adjuvant radiation therapy (RT) on regional recurrence and survival after therapeutic lymphadenectomy (TL) for clinically advanced, lymph node-metastatic melanoma. METHODS: Six hundred fifteen patients who had clinically advanced, regional lymph node-metastatic disease underwent TL. All patients were appropriate potential candidates for adjuvant RT (enlarged or multiple positive lymph nodes, extracapsular extension) because of a high risk for regional recurrence regardless of whether or not they received RT. Patient-related, tumor-related, and treatment-related variables that were associated with recurrence, survival, and treatment-related morbidity with and without RT were analyzed. RESULTS: The median follow-up was 5 years. The actuarial 5-year regional lymph node basin control rate was 81%. On multivariate analysis, the number of positive lymph nodes, the number of lymph nodes removed, and the use of adjuvant RT were associated with improved regional control. Treatment-related morbidity, particularly lymphedema, was increased with the use of adjuvant RT and an inguinal site of lymph node metastases. At last follow-up, 268 patients were alive with actuarial 5-year distant metastasis-free survival (DMFS) and disease-specific survival (DSS) rates of 40% and 48%, respectively. On multivariate analysis, DMFS and DSS both were influenced by the number of positive lymph nodes and the number of lymph nodes removed. In addition, DSS was influenced by primary tumor thickness and the receipt of adjuvant RT. CONCLUSIONS: Adjuvant RT was associated with improved regional lymph node basin control compared with TL alone in patients with high-risk, clinically advanced, lymph node-metastatic melanoma. Although it is a regional therapy, adjuvant RT also may have an impact on DSS.