Prognostic role of vitamin D receptor in digestive system tumours: A systematic review and preliminary meta-analysis.

The prognostic value of vitamin D receptor (VDR) in a variety of digestive system tumours remains controversial. In view of this, we conducted a meta-analysis. Published studies (as of Mar 30, 2023) assessing the prognostic role of VDR in digestive system tumours were retrieved. Pooled analyses were conducted based on the hazard ratios (HRs) of high VDR expression extracted from the included studies. If heterogeneity was detected, the random-effects model was used; otherwise, the fixed-effects model was used. Subgroup analysis, sensitivity analysis and meta-regression were performed to explore the sources of heterogeneity. Eight studies with 3,109 patients were included. The pooled results indicated that patients with high VDR expression generally had better overall survival (OS) (pooled HR = 0.67; 95% CI = 0.53-0.85; P = 0.001). Subgroup analyses showed that tumour type was the variable affecting the association between VDR expression and OS. VDR expression in colorectal cancer was not associated with OS (pooled HR = 0.84; 95% CI = 0.68-1.03; P = 0.086). We eliminated publication bias using the "trim and fill" method and found that high VDR expression remained an indicator of good OS (P = 0.001). Only a few studies explored the relationship between VDR expression and cancer-specific survival (CSS) or progression-free survival (PFS), and the pooled results indicated no association between them (P>0.05). VDR expression is a prognostic indicator in digestive system tumours and may also be used as a reference for vitamin D supplementation. Detection of VDR expression not only helps to evaluate prognosis but also to formulate more precise treatment plans for patients with digestive system tumours.