Risk assessment in localized primary cutaneous melanoma - A Southwest Oncology Group study evaluating nine factors and a test of the Clark logistic regression prediction model

We studied 9 clinical and pathologic factors in 259 patients using Cox model regression analysis to determine which factors have independent predictive value. Median follow-up time in all patients still alive was 12.3 years (range, 1.7 to 16.7 years). Tumor-infiltrating lymphocytes (P =.005), primary site (P =.006), and thickness (P =.02) had independent predictive value. Ulceration (P =.06) and age (P =.07) had marginal value. We used 6 of those factors to test the Clark logistic regression prediction model, which accurately predicted 8-year survival in 121 (72.9%) of 166 patients and accurately predicted melanoma-specific mortality in 32 (43%) of 74 patients. The combined or overall accuracy of the Clark model was only 64%.