Benefit of elective lymph node dissection in subgroups of melanoma patients. Results of a multicenter study of 3616 patients

Background. The benefit of elective lymph node dissection (ELND) for the treatment of the nonmetastasized malignant melanoma has been assessed differently until today. Methods. Nine medical centers with a different ELND practice but comparable standards regarding diagnosis, excision of the primary tumors, classification, and follow-up, have collected their data (primarily ascertained prospectively) of 3616 patients of the tumor categories pT2 to pT4N0M0 to produce an unbiased analysis of the prognostic benefit of ELND, and to find the indications for its application. The data are based on patients 70 years of age and younger with a primary melanoma of the skin, who have been followed for at least 4 years (median, 9.6 years). The stratification (according to pT category [alternatively, tumor thickness], sex, anatomic site) was in accordance with the results of the multivariate risk analysis (Cox hazard model). Imbalances of other criteria such as ulceration, type, and age were excluded by chi-square tests of the individual strata. The results are based on the observed survival rates according to Kaplan-Meier analysis of the different strata. Results. A prognostic benefit of the ELND group (improvement of the 5-year survival rate of about 20%) can be claimed for male patients with axial and acral melanomas (excluding lentigo maligna melanoma [LMM] and ulcerated tumors) of the categories pT3a up to pT4a (tumor thickness of > 1.5–4.5 mm, respectively) (P 2.5–5 mm, excluding LMM) (P = 0.016). Conclusions. This retrospective study strongly suggests the efficacy of ELND in subgroups of melanoma patients.