Prognostic factors in patients with thick cutaneous melanoma (> 4 mm).

Background: The current study was conducted to examine the role of multiple clinical and histologic factors in the prognostic assessment of patients with thick primary melanoma (> 4 mm, classified as T4).

Methods: A retrospective analysis was performed in 329 patients with T4 cutaneous melanomas who were seen at the University of California at San Francisco Melanoma Center between 1978 and 2000. Fourteen histopathologic features were recorded prospectively by a single dermatopathologist. In addition, 9 clinical factors were analyzed.

Results: Several histologic factors were found to have a significant impact on the survival of patients with T4 melanoma. On univariate analysis, tumor thickness, ulceration, mitotic rate, microsatellites, vascular involvement, and histogenetic type of the primary tumor all were found to have a significant impact on the overall survival rate. Regional lymph node involvement reduced the overall survival of T4 patients dramatically. The 5-year overall survival of patients with lymph node-negative T4 disease was 61%, compared with 30% for those with lymph node-positive disease. When lymph node status was taken into account, tumor thickness, vascular involvement, and ulceration all remained independent predictors of overall survival on multivariate Cox regression analysis. Neither age, gender, nor anatomic location appeared to affect the recurrence-free or overall survival rates.

Conclusions: Patients with thick primary cutaneous melanomas (> 4 mm) comprise a heterogeneous group. The presence or absence of lymph node involvement, vascular involvement, and ulceration appears to result in significantly divergent overall survival rates in this patient cohort. Consideration of these factors has important implications in the management of patients with T4 melanoma.