Prognostic factors in patients undergoing lymphadenectomy for malignant melanoma

Review of a 19-yr experience in melanoma patients undergoing lymphadenectomy revealed that the preoperative assessment of the status of the regional lymph nodes was accurate 91% of the time when the surgeon felt the nodes were clinically positive, and accurate 79% of the time when the nodes were judged clinically negative. The 10-yr survival in patients with 1-3 histologically positive nodes or no positive nodes was 50-55%, compared to a 25% 8-yr survival in patients with 4 or more histologically positive nodes. Stepwise multivariate evaluation of prognostic factors indicated that the most important factor for predicting prognosis is the number of nodes histologically involved. Node palpability was the second most important factor because of its high correlation with number of nodes histologically involved. Site of melanoma was the third most important factor, as patients with extremity (upper or lower) melanoma had a better survival (P = 0.002) than patients with axial melanoma (trunk or head and neck). Five yr following lymphadenectomy there appeared to be substantial differences in survival according to differences in the level of invasion of the primary lesion, however, these differences were not nearly as pronounced 10 yr following node dissection. The division of melanoma thicknesses into <1.50 mm and >1.50 mm provided some prognostic discrimination at 5 yr but again the differences were not pronounced 10 yr following node dissection. The thickness measurements were easier to determine than the level of invasion, and more reproducible on resubmission to the same pathologist. Four patients with melanoma less than 0.76 mm had subsequent metastases, but these may represent inadequate sampling of the primary melanoma both in the authors' series and in the 4 similar patients previously reported with such thin metastasizing melanomas.