Tumor mitotic rate added to the equation: melanoma prognostic factors changed? : a single-institution database study on the prognostic value of tumor mitotic rate for sentinel lymph node status and survival of cutaneous melanoma patients.

BACKGROUND: This study aimed to investigate the predictive value of the tumor mitotic rate per mm(2) (TMR) for sentinel lymph node (SLN) status and survival in intermediate and thick cutaneous melanoma. METHODS: Patients treated for stage I and II melanoma with wide local excision and SLN biopsy between May 1995 and May 2013 were analyzed. In case of insufficient data regarding TMR, pathology slides were reanalyzed. Prognostic factors for SLN status and survival were analyzed with the emphasis on TMR, which was analyzed as a continuous variable, dichotomized (median value) and categorized by two methods. RESULTS: The study analyzed 453 patients with complete TMR data. The median Breslow thickness was 2.20 mm, and 31.8 % of patients had tumor-positive sentinel lymph node biopsies (SLNBs). In the univariate analysis, TMR was associated with tumor-positive SLNB. This association was not significant in the multivariate analysis. Breslow thickness, primary tumor location on trunk and legs, and younger age were associated with tumor-positive SNLB. At a median follow-up of 47 months, 119 patients (26.3 %) had recurrent disease, and 92 (20.3 %) had died of melanoma. In the univariate analysis, TMR could be established as a significant prognostic factor for disease-free and disease-specific survival, but not in the multivariate analyses. Breslow thickness, ulcerated melanoma, and tumor-positive SLNB were significant prognostic factors for survival. CONCLUSION: The study was unable to establish TMR as an independent prognostic factor associated with the presence of SLN metastasis. Regarding survival, increasing TMR showed a strong association with decreased survival in the univariate analysis, but this association was rendered nonsignificant by the importance of Breslow thickness and ulceration status in the multivariate model.