Predicting ten-year survival of patients with primary cutaneous melanoma: corroboration of a prognostic model

Abstract

Background: Recently, the Pigmented Lesion Group at the University of Pennsylvania described a 4-variable model for predicting 10-year survival for patients with primary cutaneous melanoma. The variables are tumor thickness, anatomic site of the lesion, age, and gender. The objective of the current study was to test the validity of this model, employing the large data base of the New York University Melanoma Cooperative Group.

Methods: The predicted probabilities of 10-year survival for 780 patients with primary cutaneous melanoma were determined by multivariate logistic regression, using the 4 variables.

Results: The overall 10-year survival rate of the current study group was 78.4%. Of the four variables, tumor thickness, anatomic site of the lesion, and age were found to be independent predictors of survival. Although survival was better for women, gender was not a statistically significant factor in predicting 10-year survival when entered into the multivariate logistic regression model. In the current study, the probability of 10-year survival of patients with melanomas < 0.76 mm ranged from 93-99%, depending on the age and primary site. Age and site had more impact on the prognosis of intermediate and thick melanomas than on thin melanomas. Thus, for melanomas 0.76-1.69 mm, 1.70-3.60 mm, and thicker than 3.60 mm, the probabilities of survival ranged from 70-94%, 39-82%, and 23-68%, respectively.

Conclusions: The wider ranges in survival rates for thicker melanomas, depending on the other variables, emphasize the importance of including variables in addition to tumor thickness in a prognostic model. Using a large data base from a medical center, the current study supports the prognostic multivariate model of the Pigmented Lesions Group of the University of Pennsylvania; however, the authors of the current study did not find gender to be statistically significant in this multivariate model.