Research from the University of Edinburgh suggests vitamin D supplementation improves survival for patients with colorectal cancer (CRC).
The team searched PubMed and Web of Science for randomised controlled trials (RCTs) of vitamin D supplementation reporting CRC mortality. RCTs with high risk of bias were excluded from the analysis.
Seven RCTs (n=957 CRC cases) were identified. Three trials included patients with CRC at outset, and four population trials reported survival in incident cases. Two RCTs were excluded from meta-analysis.
Although trials varied in inclusion criteria, intervention dose and outcomes, meta-analysis found a 30 per cent reduction in adverse CRC outcomes with supplementation (HR, 0.70; 95% CI, 0.48-0.93).
The effect on survival was consistently observed in sub-group analyses both in trials specifically including CRC patients and in population trials reporting outcomes in incident CRC cases.
A beneficial effect on progression-free survival was seen in trials of CRC patients (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.
This is the first systematic review with meta-analysis of randomised controlled trials to examine the effect of vitamin D supplementation on survival outcomes in patients with CRC.
The meta-analysis demonstrates a clinically meaningful benefit of vitamin D supplementation on CRC survival outcomes.