Do vitamin A serum levels moderate outcome or the protective effect of vitamin D on outcome from malignant melanoma?

ABSTRACT

BACKGROUND & AIMS: Low serum vitamin D levels (25-OH-vit D2/3) are reported to be associated with thicker melanomas and poorer outcome. Vitamin A metabolites and vitamin D bind to the same heterodimeric receptor. We report a study testing the hypothesis that high vitamin A levels may reduce the protective effect of vitamin D on outcome. METHODS: Serum vitamin A levels were measured in 795 melanoma cases and assessed for association with Breslow thickness, overall (OS) and melanoma-specific survival (MSS), and modification of the effect of vitamin D levels on survival. RESULTS: Higher vitamin A levels (≥ 2.2 µmol/l) conferred a non-significant increased risk of melanoma-specific death (adjusted HR = 1.11, 95%CI(0.74-1.67), p = 0.60) but not for death overall (adjusted HR = 0.95, 95%CI(0.65-1.39), p = 0.79). There was reduction in the protective effect of vitamin D on OS in patients with high vitamin A levels (≥ 2.2 µmol/l)(HR = 0.99, 95%CI(0.72-1.36),p = 0.93) compared to patients with low levels (<2.2 µmol)(HR = 0.77, 95%CI(0.64-0.93),p = 0.007), although the difference was not statistically significant (p = 0.26). CONCLUSIONS: High vitamin A levels may reduce the protective effect of vitamin D. As sub-optimal levels of vitamin D are common in temperate climates, and are usually managed by dietary supplementation, we suggest vitamin D3 supplementation alone might be preferable for melanoma patients than preparations containing vitamin D and A.