Tumor thickness, level of invasion and node dissection in stage I cutaneous melanoma.

From a retrospective study of 97 and a prospective study of 41 Stage I cutaneous melanomas, it was found that tumor thickness is a better measure of prognosis than is the level of invasion of the tumor. The chance of developing recurrent disease appears to be directly proportional to tumor thickness. Prophylactic lymph node dissection doubled the rate of survival for patients with lesions greater than 1.50 mm thick but had no effect on those with thinner lesions. Thirty-nine per cent of the patients had lesions less than 0.76 mm thick and all survived free of disease for 5 or more years. Six per cent of the tumors that recurred or metastasized were in an intermediate range of 0.76-1.50 mm thick, and no discriminant could be found to separate these 9 lesions with a bad prognosis from the remaining 18 in this group.