High dose vitamin D supplementation does not improve outcome in a cutaneous melanoma population: results of a randomized double-blind, placebo-controlled study (ViDMe trial).

ABSTRACT

BACKGROUND: Observational studies in cutaneous melanoma have indicated an inverse relationship between levels of 25-hydroxy vitamin D and Breslow thickness, as well as a protective effect of high 25- hydroxy vitamin D levels on clinical outcome. OBJECTIVES: To evaluate whether high dose vitamin D supplementation in curatively resected cutaneous melanoma reduces melanoma relapse. METHODS: In a prospective, randomized, double-blind, placebo-controlled trial, 436 patients with resected cutaneous melanoma stage IA to III (8th American Joint Committee on Cancer staging) were randomized. Among them, 218 received a placebo while 218 received monthly 100,000 IU cholecalciferol for a minimum of 6 months and a maximum of 42 months (treatment arm). Following randomization, patients were followed for a median of 52 months, with a maximum follow-up of 116 months. The primary endpoint was relapse-free survival. Secondary endpoints were melanoma-related mortality, overall survival, and the evolution of 25-hydroxy vitamin D serum levels over time. RESULTS: In our population (mean age 55 years, 54% female) Vitamin D supplementation increased 25- hydroxy vitamin D serum levels after 6 months of supplementation in the treatment arm by a median 17 ng/ml (95%CI 9; 26) compared to 0 ng/ml (95%CI -6; 8) in the placebo arm (P < 0.001; Wilcoxon test) and remained at a steady state during the whole treatment period. The estimated event rate for relapse-free survival at 72 months after inclusion was 26.51% in the vitamin D supplemented arm (95% CI 19.37; 35.64) versus 20.70% (95%CI 14.26; 29.52) in the placebo arm, [hazard ratio 1.27 (95%CI 0.79; 2.03), P = 0.32]. After adjusting for confounding factors (including baseline stage, body mass index, age, gender, and baseline season), the hazard ratio was 1.20 (95% CI 0.74; 1.94, P = 0.46). Deaths from progression of cutaneous melanoma and non-melanoma related deaths were similar in both vitamin D supplemented and placebo group (n = 10 and 11 and n = 3 and 2, respectively). No major adverse events were observed during the study. CONCLUSION: In cutaneous melanoma patients, monthly high dose vitamin D supplementation was safe, resulted in a sustained increase in 25-hydroxy vitamin D levels during the treatment period, but did not improve relapse-free survival, melanoma-related death or overall survival.