Adherence to Plant-Based Dietary Patterns and Digestive Cancers: A Scoping Review

Background/Objectives: Digestive cancers are among the leading causes of death worldwide. Although their etiology is not fully understood, diet is an important modifiable risk factor. This scoping review aimed to explore the existing evidence on the association between adherence to various plant-based dietary (PBD) patterns and the risk of major digestive cancers. Methods: The scoping review followed the Arksey and O’Malley framework and Joanna Briggs Institute recommendations, and results were reported according to PRISMA-ScR guidelines. A systematic search was performed in PubMed/MEDLINE, Scopus, EMBASE, and Web of Science between January 2020 and May 2025. Original observational studies and clinical trials in English or Spanish examining the association between PBD patterns and digestive cancers were included. Results: A total of 24 studies were identified, including 16 prospective cohort studies and 8 hospital-based case–control studies, conducted mainly in Europe (n = 10), North America (n = 8), and Asia (n = 6). Most studies used food frequency questionnaires and predefined PBD indices, particularly the plant-based diet index (PDI), healthful (hPDI), and unhealthful (uPDI) (n = 13), while others assessed pro-vegetarian (n = 2) or EAT-Lancet dietary patterns (n = 3). Most studies reported protective associations with all digestive cancer localizations examined, particularly in relation to healthful PBD patterns: colorectal (13/15), pancreatic (6/7), liver (4/4), esophageal (4/5), stomach (3/4) and oropharyngeal (2/2) cancers. On the contrary, unhealthful PBD patterns were linked to a higher risk. Conclusions: Overall, the findings of this review highlight that the quality of PBD patterns is crucial for digestive cancer risk. PBD patterns emphasizing whole and minimally processed plant foods were protective, while those characterized by refined or ultra-processed plant products were deleterious. A future standardization of PBD indices would help to improve comparability among studies.