Effects of Circulating 25(OH)D Status in Advanced Colorectal Cancer Patients Undergoing Chemotherapy: A Systematic Review.

BACKGROUND/AIM Colorectal cancer (CRC) is a disease of poor prognosis. An advantageous connection between vitamin D supplementation and prognostic improvement was depicted in CRC patients. However, the effects of circulating vitamin D on cancer outcomes are unclear for advanced CRC patients, especially for those receiving chemotherapy. MATERIALS AND METHODS The review was registered on PROSPERO (register number: CRD42021243547). PUBMED, EMBASE, Cochrane Library, and Web of Science were searched for English-language publications using relevant keywords. Two reviewers independently selected articles, assessed quality, and extracted data. We applied RevMan5.4 and Stata14 for meta-analysis. RESULTS We included an RCT and three prospective cohort studies, which were of high overall quality. Higher circulating 25(OH)D level was related with better disease outcomes in advanced CRC patients undergoing chemotherapy: progression-free survival (HR=0.85, 95% CI=0.71-0.99; I2=34.4%), overall survival (OR=0.56, 95% CI=0.38-0.82; I2=0%). CONCLUSION High circulating 25(OH)D content is beneficial for improving prognosis of advanced CRC receiving chemotherapy.