Impact of extra-nodal extension and AJCC lymph node staging in predicting recurrence following lymphadenectomy in patients with melanoma.

Background: Regional lymphadenectomy (RL) has traditionally been recommended in patients with melanoma found to have clinical lymphadenopathy or a positive sentinel lymph node biopsy (SLNB). Regional control of disease is still a relevant issue for patients, even after undergoing lymphadenectomy. The goal of this study was to identify the clinicopathologic characteristics that predict locoregional recurrence in patients who have undergone either therapeutic lymph node dissection (TLND) or completion lymph node dissection (CLND) following SLNB.

Methods: Retrospective review of population-based cohort of patients with melanoma lymph node metastasis from the years 2005-2015. Multivariate, proportional hazards regression analysis was performed to determine factors predicting nodal recurrence.

Results: 586 patients underwent a RL, with a median follow up of 35 months. Overall, in-basin recurrence rates in the axilla, groin, and head/neck were 7.7 ​%, 8.7 ​% and 9.2 ​%, respectively. Higher unadjusted recurrence rates occurred following CLND than TLND of the groin (12.8 ​% vs 4.5 ​%) and neck (10.0 ​% vs 4.7 ​%) but not the axilla (7.5 ​% vs 8.0 ​%). Upon multivariate analysis, ENE (HR 2.77; p=<0.0001) and the AJCC lymph node stage (N3 vs N1) (HR 2.51; p ​= ​0.025) were predictive of regional recurrence.

Conclusion: The AJCC nodal stage and the presence of extranodal extension were the only variables impacting regional recurrence following regional lymphadenectomy for melanoma. When considering regional disease control, they should be factored into treatment decisions, and surveillance strategies.