Prophylactic lymph node dissection in clinical stage I cutaneous malignant melanoma: results of surgical treatment in 1319 patients.

A retrospective study was made of 1319 patients with cutaneous primary malignant melanoma and regional lymph nodes clinically free of disease, whose first definitive surgical treatment was either (a) wide excision of the primary lesion (WE) or (b) wide excision of the primary lesion plus a prophylactic lymph node dissection (PLND). Patients were stratified according to three dominant prognostic factors, as revealed by multifactorial analyses: sex of patient, the anatomical site and thickness of the primary lesion. Of 380 patients who underwent PLND for lymph nodes clinically free of disease, there was microscopic evidence of nodal metastases in 5 per cent. Despite this, prognosis in these patients was nearly twice as good as in those patients undergoing lymph node dissection for clinically involved nodes. Five-year survival rates for all those clinical stage I patients with lesions less than 0.8 mm thick were high irrespective of initial surgical treatment. In men with lesions of intermediate thickness (particularly 1.6-3.0 mm), survival rates for those undergoing PLND were considerably higher than for those undergoing WE. There were no survival benefits of PLND in men with lesions thicker than 3.0 mm. This was in contrast to the situation in women, where PLND was indicated for patients with the thickest lesions. This study has defined three parameters which can serve as useful practical guides for selecting alternative surgical procedures in the management of clinical stage I cutaneous malignant melanoma.