Vitamin D and gastric cancer - A systematic review and meta-analysis.

Objective: to explore the association between serum vitamin D level and the occurrence and pathological grade of gastric cancer. Material a nd methods: search PubMed, Embase, Web of Science, Cochrane and Chinese database; all articles about the association between serum vitamin D levels and gastric cancer published before July 2021. Results: 10 trials with 1159 cases of gastric cancer patients and 33,387 cases of regular control patients were analyzed. The serum vitamin D level of the gastric cancer group (15.56 ± 7.46 ng/ml) was lower than in the control group (17.60 ± 1.61 ng/ml), and the difference was statistically significant. The patients with gastric cancer, clinical stage III/IV (16.19 ± 8.04 ng/ml) had lower vitamin D levels than those with stage I/II (19.61 ± 9.61 ng/ml), and the patients with low differentiation of gastric cancer (17.5 ± 9.5 ng/ml) had lower levels than those with well- or moderately-differentiated cancer (18.04 ± 7.92 ng/ml). The patients with lymph node metastasis (19.41 ± 8.63 ng/ml) had lower vitamin D levels than the patients without lymph node metastasis (20.65 ± 7.96 ng/ml), and the difference was statistically significant. Conclusion: vitamin D levels were negatively associated with gastric cancer. Vitamin D levels were significantly associated with different clinical stages, degrees of differentiation, and lymph node metastasis, suggesting that low vitamin D levels might predict poor prognosis in gastric cancer.