Does mitotic rate predict sentinel lymph node metastasis or survival in patients with intermediate and thick melanoma?

Background: The significance of mitotic rate (MR) in melanoma remains controversial. Methods In this retrospective analysis of a prospective randomized trial that included patients with melanoma of 1.0 mm or greater, all patients underwent wide excision and sentinel node (sentinel lymph node [SLN]) biopsy. Univariate and multivariate analyses were performed to evaluate factors predictive of disease-free survival (DFS) and overall survival (OS). Results A total of 551 patients had MR reported. A cut-off point of 6 mitoses/mm ² best discriminated DFS and OS: 455 patients (82.6%) had MR less than 6/mm². SLN were tumor-positive in 14.7% of low MR versus 31.3% of high MR patients (P = .0003). There were significant differences in DFS (P = .0014) and OS (P = .0002) between the 2 groups, however, MR failed to remain significant in the multivariate model. Conclusions MR is weakly predictive of SLN status but it is not an independent predictor of survival for melanomas 1.0 mm or thicker.