Lymph node dissection in stage III melanoma patients: Survival yields and determining factors

Background: The Multicenter Selective Lymphadenectomy Trial II has failed to show overall survival advantage for lymph node dissection (LND) of patients with microscopic sentinel lymph node (SLN) metastases. Objective. To analyze the survival of melanoma patients after LND and to identify predictors of survival after LND. Methods: Longitudinal study enrolling patients having undergone completion LND (CLND) or therapeutic LND (TLND) from January 2001 to December 2015. Study variables recorded were: age, gender, Breslow, SLN biopsy, N-stage, number of metastatic lymph nodes, number of lymph nodes dissected, melanoma death, and regional recurrence. Main outcome measures were the melanoma-specific survival (MSS), and regional lymph node recurrence free survival (RFS). Explanatory variables of survival were identified through the Kaplan-Meier and log-rank tests. Classification trees were designed to order predictor factors. Results: A total of 331 patients were enrolled, with a mean age of 54.4 (95% CI 52.7-56.1) and gender predominance of men (61.3% vs. 38.7%). The median follow-up was 41.0 months (range 0-185 months). At the end of the study period 38.7% of the patients died of melanoma. Three-year and 5-year cumulative melanoma-specific survival was 71.2% and 60.5%, respectively. Log Rank test identified significantly improved MSS in patients younger than 70, women, microscopic SLN metastasis, and N1-N2 stage. As for the reason for LND, patients undergoing CLND showed the longest MSS (3-year MSS 82.7%, 5-year MSS 70.4%), followed by patients undergoing TLND over the follow-up (3-year MSS 63.5%, 5-year MSS 51.9%). TLND for metastases clinically identified at the time of diagnosis of primary melanoma disclosed the shorter survival (3-year MSS 45.0%, 5-year MSS 39.0%). N3 stage, TLND at primary diagnosis, and age >70 were hierarchically ordered as predictors of melanoma death. Recurrence at the same lymph node basin was observed in 14.8% (n = 49). Three-year and 5-year RFS was 87.4% and 82.9%, respectively. Incomplete dissection, a ratio metastatic nodes/nodes removed >0.4, age >70, N3, and groin dissections related to shorter RFS. Non-SLN metastases were not found in 78% (n = 163) of the CLND. Conclusions: Lymph node dissection remains a procedure with remarkable survival yields, both in MSS and RFS with longer MSS standing on lower metastatic burden. CLND provides better MSS than LND performed in patients with clinically detected metastasis.