Prognostic Value of Baseline Serum 25-Hydroxyvitamin D in High-Risk Resected Cutaneous Melanoma

Objective: Vitamin D has been proposed as a potential prognostic biomarker in melanoma, but its significance in the postoperative setting remains unclear. This study investigated the association between baseline serum 25-hydroxyvitamin D [25(OH)D] levels and relapse-free survival (RFS) in patients with completely resected stage II–III cutaneous melanoma. Materials and Methods: In this retrospective multicenter study, 154 patients with resected cutaneous melanoma and available baseline serum 25(OH)D measurements obtained within 3 months before or after surgery were included. Patients were categorized as having low (≤20 ng/mL) or high (>20 ng/mL) vitamin D levels. Associations between clinicopathologic variables and vitamin D status were examined, and RFS was assessed using Kaplan–Meier analysis and Cox proportional hazards regression models. Results: Of the 154 patients, 81 (58.5%) had low and 73 (41.5%) had high vitamin D levels. The median follow-up was 65 months, during which 67 relapse events occurred. Median RFS was 54.1 months (95% CI, 35.2–73.0) in the low vitamin D group and 89.2 months (95% CI, 68.3–110.2) in the high vitamin D group (p < 0.001). In univariable Cox analysis, stage III disease (HR, 3.30; 95% CI, 1.84–5.90; p < 0.001), absence of adjuvant therapy (HR, 1.98; 95% CI, 1.21–3.23; p = 0.006), low vitamin D level (HR, 2.68; 95% CI, 1.59–4.51; p < 0.001), and higher Breslow thickness (HR, 1.04; 95% CI, 1.01–1.09; p = 0.048) were associated with poorer RFS. In multivariable analysis, stage III disease (HR, 3.05; 95% CI, 1.52–6.11; p = 0.002) and low vitamin D level (HR, 2.61; 95% CI, 1.52–4.49; p < 0.001) remained independent predictors of inferior RFS. Conclusions: Baseline serum 25(OH)D was independently associated with RFS in resected stage II–III cutaneous melanoma. Lower vitamin D levels were linked to shorter RFS, suggesting that vitamin D status may provide complementary prognostic information in the postoperative setting. Prospective validation is warranted.