The Role of Vitamin D on the Prognosis and Incidence of Lung Cancer: A Systematic Review and Meta-Analysis

Background: The correlation between vitamin D intake and lung cancer development is controversial. This meta-analysis aims to evaluate the relationship between vitamin D and the prognosis and incidence of lung cancer. Methods: A comprehensive database search on Pubmed, Web of Science, EBSCO, and Cochrane Library was carried out from the beginning to November 2020. Long-term survival and the incidence rate of patients with lung cancer were the primary outcomes of the study. Results: Ten eligible studies were selected for the meta-analysis following specific inclusion and exclusion criteria. Four included studies, covering 5007 patients, compared the overall survival (OS) and relapse-free survival (RFS) of lung cancer patients among total vitamin D users with non-users. Significantly, the estimated pooled hazard ratio (HR) revealed that vitamin D could improve OS and RFS of lung cancer patients [HR=0.83, 95% CI (0.72-0.95); HR=0.79, 95% CI (0.61-0.97), respectively]. Vitamin D intake was inversely associated with lung cancer incidence in six studies [OR=0.90, 95% CI (0.83-0.97)]. Conclusions: The present meta-analysis shows vitamin D not only improves the long-term survival of lung cancer patients but has a beneficial effect on the incidence of lung cancer. Notwithstanding, more studies are needed to confirm the study results.