Newly-identified Pathways Relating Vitamin D to Carcinogenesis: A Review

Abstract

Background: The epidemiological relationship between vitamin D levels and cancer has been thoroughly investigated. Published data from large studies appear to corroborate a significant relationship between higher serum vitamin D concentrations and improved survival. Mechanistic reviews on commonly-studied cancers - including breast cancer, colon cancer and melanoma - focus predominantly on data from older studies. In outlining avenues for future research, we believe there is utility in summarizing novel findings introduced to the literature.

Materials and methods: In this narrative review, we used MEDLINE, PUBMED and Cochrane databases to identify mechanistic studies published from January 1, 2015 onwards exploring this topic.

Results: Twenty-five mechanistic studies were included in this review. It was found that vitamin D plays a critical role in both direct (i.e. tumor gene expression, proliferation, invasiveness, sensitivity to chemotherapy etc.) and indirect (i.e. effects on the tumor microenvironment and immunomodulation) tumor suppression mechanisms.

Conclusion: These newly-identified pathways warrant further research, with the hopes that we may understand how and when vitamin D supplementation can be integrated into precision medicine therapeutics for cancers of the breast, colon and skin. Cancer care providers should consider recommendations to screen for vitamin D deficiency in this population.

Keywords: Vitamin D; breast cancer; calcitriol; cancer risk; cholecalciferol; colorectal cancer; skin cancer; ergocalciferol; review; survival.

Figure 1. Flow chart outlining algorithm of article inclusion.

Figure 2. Overview of newly-identified mechanisms relating vitamin D to carcinogenesis or disease progression.