Do melanoma patients from Southern climates have a worse outcome than those from Northern climates?

Sun exposure is known to cause melanoma; what is not known is whether patients from the Southern United States have a different profile of clinicopathologic factors and outcomes than those from the Northern United States. Data from a prospective, randomized trial on surgery for cutaneous melanoma were analyzed. All patients underwent wide excision and sentinel lymph node biopsy. Patients were categorized into two groups: Northern or Southern according to their state of residence. Clinicopathologic factors and outcomes were compared between groups. A total of 2025 patients were included in the analysis; 1214 (60%) were from Southern states. The median follow-up was 52 months. Despite significant differences in clinicopathologic features between groups on both univariate and multivariate analysis, two important factors, namely primary tumor thickness and ulceration were not different, nor was the rate of lymph node metastasis. Additionally, there were no differences in disease-free survival or overall survival between the two groups. Significant differences exist between primary melanomas based on geographic regions; however there are no differences in survival. Cumulative versus episodic sun exposure may play some role in these differences.