Predicting five-year outcome for patients with cutaneous melanoma in a population-based study.

BACKGROUND: In numerous studies tumor thickness has been shown to be the most important prognostic factor for patients with localized cutaneous melanoma. However, to our knowledge there are no population-based studies analyzing the prognosis of patients living in the United States with cutaneous melanoma.
METHODS: A prognostic model was developed with death as an outcome for 548 patients from Connecticut with localized cutaneous melanoma. Only patients with invasive melanoma who either died of the disease or were followed-up at least five years were studied. Fourteen pathologic parameters (histologic type of melanoma, Clark level, microscopic satellites, histologic regression, tumor thickness [Breslow], ulceration, vascular invasion, mitotic rate per mm2, tumor-infiltrating lymphocytes, radial vs. vertical growth phase, solar elastosis, co-existing nevus, lymphocytic response, and pigmentation) and three clinical variables (age, sex, and anatomic site) were analyzed using logistic regression.
RESULTS: After univariate analysis, 10 pathologic variables showed prognostic significance: histologic type (nodular and "other" types only), Clark level, microscopic satellites, regression (protective), tumor thickness, ulceration, vascular invasion, mitotic rate, vertical growth phase, and solar elastosis (protective). In the final model employing multivariate analysis, only tumor thickness and mitotic rate continued to have independent predictive value.
CONCLUSIONS: In this population-based study of 548 patients in Connecticut, tumor thickness was the most significant prognostic factor for survival of patients with localized cutaneous melanoma. Other prognostic factors studied to date have not been conclusively verified as providing any additional information beyond that of tumor thickness.