Background: Early stage melanoma of the lower extremity is generally associated with a favorable prognosis. However, several retrospective studies have suggested that melanoma on the foot portends poor survival. The authors hypothesized that the region of the lower extremity has prognostic importance.
Methods: Between January 1, 1971, and December 31, 1991, 652 patients were seen at the John Wayne Cancer Institute for a primary melanoma on the foot (92 patients), calf (336 patients), or thigh (224 patients). All patients had clinically or histopathologically negative regional lymph nodes. The duration of follow-up after first diagnosis was 9 -302 months, with a minimum of 6 years for survivors. Survival curves were estimated by the Kaplan-Meier method. Pearson chi-square test was used to test differences associated with the regional site of the lower-extremity melanoma. The log rank test was used for univariate analysis, and Cox proportional hazards regression was used for multivariate analysis.
Results: Univariate analysis identified regional site, gender, Breslow depth, Clark level, and age at diagnosis as significant for both overall survival (OS) and disease free survival (DFS) (P = 0.0001). Multivariate analysis confirmed regional site as an independent prognostic variable for OS (P = 0.0002) and DFS (P = 0.0005). Ten-year rates of OS and DFS were 71% and 66%, respectively, for patients with foot melanomas, compared with 92% and 87% for those with calf melanomas and 95% and 94% for those with thigh melanomas.
Conclusions: The prognosis for patients with primary melanoma of the lower extremity is affected by the distance of the lesion from the trunk. Thus, distal (foot) lesions carry a higher risk than thigh lesions. This difference should be considered as a covariate when stratifying patients in clinical trials.