Dietary inflammatory index and pancreatic cancer risk: a systematic review and dose-response meta-analysis

Objective: The meta-analysis was conducted to test the link between pancreatic cancer (PC) risk and dietary inflammatory index (DII(R)) score. Design: Systematic review and meta-analysis. Setting: We searched PubMed, Embase, Web of Science and the Cochrane Library up to 22 November 2020 to identify the relevant studies. Studies that reported the risk estimates and the corresponding 95 % CI for the DII category and PC risk were included. The effect sizes were pooled using the random-effects model. Dose-response analysis was conducted where possible. Participants: Two prospective cohort studies of 634 705 participants (3152 incident cases), and four case-control studies of 2737 cases and 4861 controls. Results: Overall, the pooled risk ratio (RR) indicated that individuals in the highest category compared with the lowest category had an increased PC risk (RR = 1.45; 95 % CI 1.11, 1.90; P = 0.006). Meanwhile, significant heterogeneity was also revealed. The dose-response meta-analysis indicated that a 1-unit increase in the DII score was associated with the PC risk (RR = 1.08; 95 % CI 1.002, 1.166; P = 0.045; I-2 = 94.1 %, P < 0.001). Nonlinear result showed an increased risk of moving from fewer to more inflammatory borders with increasing DII score (P-nonlinearity = 0.003; I-2 = 76.5 %, P < 0.001). Subgroup analyses found that significant positive association between PC risk and DII score appeared to be in case-control studies (RR = 1.70; 95 % CI 1.16, 2.50; P = 0.007) and studies with <= 31 DII components (RR = 1.76; 95 % CI 1.14, 2.72; P = 0.011). Conclusion: These findings suggested dietary habits with high inflammatory features (high DII score) might increase PC risk.