Predictors of late mortality in cutaneous malignant melanoma - A population-based study in Sweden

Abstract

We determined risk factors for late deaths from cutaneous malignant melanoma (CMM) based on clinical characteristics at diagnosis, initial surgical treatment, histopathologic features of the primary tumor and type of eventual recurrences during follow-up. We examined deaths from CMM 8 or more completed years after the initial diagnosis in a case-control study nested in a nationwide cohort comprising all 8,838 patients with CMM diagnosed in Sweden during 1960-1978 with complete follow-up through 1986. There were 285 case patients and 285 control patients, individually matched by sex, age and follow-up time. Conditional logistic regression was used to obtain odds ratios (OR) as estimates of the relative risk. The risk of late mortality increased stepwise, almost 19-fold, with increasing tumor thickness from ≤0.75 to ≤7.00 mm. Besides the thickest tumors (≤7.00 mm), those of intermediate thickness (1.50-2.49 mm) had the highest risk (OR 8.5). After adjustment for tumor thickness, non-radical primary surgical treatment increased the risk of late mortality almost 3-fold while prophylactic lymph node dissection entailed a significantly reduced risk of late mortality (OR 0.5); the histopathologic features increasing level of invasion and vertical growth phase also remained significantly associated with a poor outcome. In a multivariate model, non-radical primary surgical treatment, prophylactic lymph node dissection, vertical growth phase, level of invasion and lymphocytic reaction were independent predictors of late mortality.