Effect of Vitamin D Supplementation on the Prognosis of Colorectal Cancer: A Meta-analytic Approach of Randomized Controlled Trials

Abstract

Colorectal cancer is a common cancer worldwide. Its prognosis is of great importance. It seems that vitamin D supplementation may improve the prognosis of colorectal cancer. However, there is no cutoff point for the daily dose of vitamin D. In this regard, we intend to perform a rapid umbrella review and dose-response meta-analysis of randomized controlled trials. A rapid umbrella review with dose-response meta-analysis was conducted based on the resources Google Scholar, Scopus and PubMed. The eligible documents were the systematic reviews reporting survival (hazard ratio [HR]) of colorectal cancer patients. Dose-response meta-analysis was conducted on the HRs and daily dose of vitamin D supplementation based on quadratic meta-regression. A total of five articles were selected for qualitative umbrella review that one article was suitable for dose-response meta-analysis including five clinical trials. According to the results of dose-response meta-analysis, a decreasing trend was observed in HR for higher doses of vitamin D. The best cutoff point for significant better survival was 3000 IU/day. Vitamin D with doses 3000 IU/day and more could increase survival of colorectal cancer patients. Nevertheless, the side effects of such doses should be regarded in clinics.