Sun Exposure Patterns Affect Melanoma Location but Not Prognostic Features

Cutaneous melanoma (CMM) is an aggressive malignancy whose incidence continues to rise worldwide. Ultraviolet (UV) radiation from natural and artificial sources is a major environmental risk factor and is classified as a Group 1 carcinogen by the International Agency for Research on Cancer. The present study aimed to evaluate the association between sun exposure patterns and the clinicopathological characteristics of patients with cutaneous melanoma, focusing on tumor thickness and markers of tumor aggressiveness.

This retrospective cohort study included 115 patients with histologically confirmed primary cutaneous melanoma treated in our Plastic Surgery Department between January 2018 and December 2022. Demographic, clinical and histopathological data were collected from medical records and Breslow thickness was categorized as thin (≤2 mm) or thick (>2 mm). Statistical analysis included chi-square and Mann-Whitney U tests, followed by multivariate logistic regression to identify predictors of increased tumor thickness. A p-value < 0.05 was considered statistically significant.

Statistically significant associations were identified between several clinicopathological variables and melanoma characteristics. Sun exposure pattern was significantly associated with tumor anatomical location [χ²(6) = 85.11, p < 0.001], with chronic exposure predominantly linked to melanomas of the posterior trunk, while intermittent exposure was more frequently observed in melanomas of the lower limbs. Patients with thick melanoma were significantly older than those with thin tumors (p = 0.032). Melanoma thickness was also significantly associated with histological subtype (p = 0.002), ulceration (p < 0.001), and mitotic activity (p = 0.002), with nodular melanoma, ulcerated tumors, and lesions with increased mitotic activity more frequently presenting greater Breslow thickness. Metastatic disease occurred more often in patients with thick melanomas (p = 0.046). In multivariate analysis, mitotic activity remained an independent predictor of thick melanoma [OR = 1.75, p < 0.001], while ulceration showed borderline significance (odds ratio [OR) = 4.14, p = 0.050]. Overall, sun exposure pattern was associated with melanoma location but not with markers of tumor aggressiveness.

Sun exposure pattern was associated with melanoma anatomical location but not with tumor aggressiveness. Increased mitotic activity was the strongest independent predictor of thick melanoma, while ulceration showed borderline significance. These findings suggest that intrinsic tumor characteristics play a greater role in melanoma progression than sun exposure patterns.