Effect of Vitamin D Deficiency on Liver Cancer Risk: A Systematic Review and Meta-Analysis

Epidemiological studies have showed that vitamin D deficiency can increase the risk of liver cancers. Hence, we conducted a meta-analysis to explore the relationship between 25-hydroxyvitamin D [25(OH)D] levels and liver cancer risk. METHODS: Cochrane Library, Medline, Web of Science, and Embase were searched up to Mar. 2020, and the references of those studies were also searched by hand. A meta-analysis of 11 studies was performed which met the inclusion criteria. Six case–control studies and five cohort studies were included. RESULTS: A total of 11 studies (6 case–control and 5 cohort studies) with 12,895 incident cases were included in the meta-analysis. The meta-analysis showed that liver cancer risk was significantly increased for vitamin D deficiency, and the pooled RR and its 95% CIs was 2.16 (1.2, 3.88; P = 0.01). In comparative analyses between 25(OH)D levels in patients with hepatocellular carcinoma(HCC) and those in the control group individuals, the summary RR of liver cancer was -1.11 (95% CI=-1.96 to -0.25). The subgroup analysis of the different geographical region of the population showed that the risk of liver cancer in Asian subgroup, European subgroup and Egyptian subgroup increased for vitamin D deficiency (RR=1.34,95% CI 0.72 to 2.48, P<0.00001; RR=2.53,95% CI 1.62 to 3.93,P<0.0001;RR=29.5,95% CI 4.14 to 209.93, P=0.88). CONCLUSION: The results of this meta-analysis indicate that vitamin D deficiency is associated with increased risk of liver cancer. The 25(OH)D3 levels are lower in HCC patients than those in health controls. Maintenance of sufficient serum vitamin D levels would be beneficial for prevention of liver cancer.