Prognostic significance of tumor mitotic rate in T2 melanoma staged with sentinel lymphadenectomy.

ABSTRACT

BACKGROUND AND OBJECTIVES: Tumor mitotic rate (TMR) is an important prognostic variable for patients with thin melanoma. However it remains unclear what the significance of TMR is for more deeply invasive melanoma pathologically staged with a sentinel lymph node biopsy. We sought to determine the prognostic value of TMR in clinically node-negative T2 melanoma patients staged with sentinel lymphadenectomy. METHODS: A prospective IRB-approved database of cutaneous melanoma patients treated from 09/01/1997-03/01/2011 was used to identify patients with T2 melanoma staged with a SLN. Associations were evaluated using Fisher's Exact test, and Kaplan-Meier analysis. RESULTS: Three hundred thirteen T2 patients were included. 19% had ulceration, 11% a positive sentinel node (SLN), and 10% recurred. 44% of patients had TMR ≥ 1/mm(2). TMR ≥ 1/mm(2) did not predict SLN status. TMR ≥ 1/mm(2) was significantly associated with recurrence in SLN negative patients; only 3% of those with TMR < 1/mm(2) developed a recurrence compared to 16% of those with TMR ≥ 1/mm(2) (P < 0.0001). CONCLUSIONS: Although TMR ≥ 1/mm(2) is not associated with risk of SLN involvement in T2 melanoma, it is a significant risk factor for recurrence when SLN negative. As such, TMR could be used to stratify follow-up regimens in SLN negative T2 patients.