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The effect of vitamin D supplementation on survival in patients with colorectal cancer: Systematic review and Meta-analysis of Randomised Controlled Trials

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Low circulating vitamin D levels are associated with poor colorectal cancer (CRC) survival. We assess whether vitamin D supplementation improves CRC survival outcomes.

PubMed and Web of Science were searched. RCTs of vitamin D supplementation reporting CRC mortality were included. RCTs with high risk of bias were excluded from analysis. Random-effects meta-analysis models calculated estimates of survival benefit with supplementation. PROSPERO:CRD42020173397

7 RCTs (n=957 CRC cases) were identified: three trials included patients with CRC at outset, four population trials reported survival in incident cases. Two RCTs were excluded from meta-analysis (high risk of bias; no hazard ratio). Whilst trials varied in inclusion criteria, intervention dose and outcomes, meta-analysis found a 30% reduction in adverse CRC outcomes with supplementation (n=815, HR=0.70; 95%CI:0.48-0.93). A beneficial effect was seen in trials of CRC patients (progression-free survival, HR=0.65; 95%CI:0.36-0.94), with suggestive effect in incident CRC cases from population trials (CRC-specific survival, HR=0.76; 95%CI:0.39-1.13). No heterogeneity or publication bias was noted.

Meta-analysis demonstrates a clinically meaningful benefit of vitamin D supplementation on CRC survival outcomes. Further well-designed, adequately powered RCTs are needed to fully evaluate benefit of supplementation in augmenting ‘real life’ follow-up and adjuvant chemotherapy regimens, as well as determining optimal dosing.

ID: 161618937