The prognostic value of tumor mitotic rate in children and adolescents with cutaneous melanoma: A retrospective cohort study.

BACKGROUND: Mitotic rate is a strong predictor of outcome in adult patients with primary cutaneous melanoma, but for children and adolescent patients this is unknown. OBJECTIVE: We sought to assess the prognostic value of primary tumor mitotic rate in children and adolescents with primary melanoma. METHODS: This was a cohort study of 156 patients who were <20 years of age and who had clinically localized cutaneous melanoma. Patients <12 years of age were classified as children and those 12 to 19 years of age as adolescents. Clinicopathologic and outcome data were collected. Recurrence-free and melanoma-specific survival were calculated. Univariable and multivariable analyses were performed using Cox proportional hazard models. RESULTS: Thirteen of 156 patients (8%) were children. The mitotic rate was ≥1/mm2 in 104 patients (67%) and correlated with increasing Breslow thickness. A positive sentinel node was found in 23 of 61 patients (38%) in whom a sentinel lymph node biopsy specimen was obtained. The median follow-up was 61 months. Five-year melanoma-specific and recurrence-free survival rates were 91% and 84%, respectively. Mitotic rate was a stronger predictor of outcome than tumor thickness and was the only factor independently associated with recurrence-free survival. LIMITATIONS: This research was conducted at a single institution and the sample size was small. CONCLUSION: Mitotic rate is an independent predictor of recurrence-free survival in children and adolescents with clinically localized melanoma.