Healthful Plant-Based Diet Index (hPDI) and risk of upper gastrointestinal cancer: A meta-analysis.

Abstract

331 Background: The relationship between plant-based dietary patterns and upper gastrointestinal (GI) cancers remains unclear. The Healthful Plant-Based Diet Index (hPDI) is a tool that measures adherence to plant-based diet and generates “scores” for clinical comparison. We conducted a systematic review and meta-analysis to examine the association between hPDI and the risk of esophageal and gastric cancers. Methods: A PubMed search identified relevant studies reporting on the association between hPDI and upper GI cancers. Reference lists were manually searched for additional studies. Study selection followed PRISMA guidelines, and quality was assessed using the Newcastle–Ottawa Scale (NOS). Pooled risk estimates were calculated using inverse-variance fixed-effects models, with subgroup analyses by cancer type. Sensitivity analyses were conducted using leave-one-out approach and by switching between fixed- and random-effects models. Forest plots and funnel plots were generated with RevMan 5.4, while Begg’s and Egger’s tests for publication bias were performed using Stata 15. Results: A total of four studies were included, all with high NOS scores. Overall, higher hPDI scores were associated with a significantly lower risk of upper GI cancers (RR = 0.64, 95% CI: 0.56–0.75). In subgroup analyses, the inverse association was consistent for both esophageal cancer (RR = 0.66, 95% CI: 0.54–0.79) and gastric cancer (RR = 0.63, 95% CI: 0.50–0.79). Between-study heterogeneity was low (I² = 35%, P = 0.16). Publication bias assessment indicated no evidence of small-study effects, as Begg’s test was non-significant (P = 0.88) and Egger’s test showed no significant bias (P = 0.76). Sensitivity analyses confirmed the robustness of the findings, with consistent results after sequential exclusion of individual studies and when using random-effects models. Conclusions: Higher hPDI scores were associated with a significantly reduced risk of esophageal and gastric cancers, indicating that adherence to a healthy plant-based diet may reduce upper GI cancer risk. These findings highlight the potential role of dietary modification in upper GI cancer prevention.