Oral Bacterial Microbiota in Digestive Cancer Patients: A Systematic Review.

Elisa Reitano,Nicola De’Angelis,Maria Clotilde Carra,Federica Gaiani,Riccardo Inchingolo,Giorgio Bianchi,Paschalis Gavriilidis,Gian Luigi De’Angelis,Riccardo Memeo

doi:10.3390/microorganisms9122585

Abstract

The relation between the gut microbiota and human health is increasingly recognized. Recently, some evidence suggested that dysbiosis of the oral microbiota may be involved in the development of digestive cancers. A systematic review was conducted according to the PRISMA guidelines to investigate the association between the oral microbiota and digestive cancers. Several databases including Medline, Scopus, and Embase were searched by three independent reviewers, without date restriction. Over a total of 1654 records initially identified, 28 studies (2 prospective cohort studies and 26 case-controls) were selected. They investigated oral microbiota composition in patients with esophageal squamous cell carcinoma (n = 5), gastric cancer (n = 5), colorectal cancer (n = 9), liver carcinoma (n = 2), and pancreatic cancer (n = 7). In most of the studies, oral microbiota composition was found to be different between digestive cancer patients and controls. Particularly, oral microbiota dysbiosis and specific bacteria, such as Fusobacterium nucleatum and Porphyromonas gingivalis, appeared to be associated with colorectal cancers. Current evidence suggests that differences exist in oral microbiota composition between patients with and without digestive cancers. Further studies are required to investigate and validate oral–gut microbial transmission patterns and their role in digestive cancer carcinogenesis.

Highlights

A specific research equation was used for each database, using the following keywords and MeSH terms: oral microbiome, oral microbiota, mouth microbiome, gastrointestinal neoplasms, gastrointestinal cancers, gastrointestinal carcinoma, digestive cancer, digestive neoplasms
The available evidence suggests that digestive cancer patients present an oral microbiota composition that differs from non-cancer controls and specific oral bacteria may be linked to increased odds for digestive cancers
More studies are available concerning the role of oral microbiota in pancreatic cancer (PC), gastric cancer (GC), esophageal cancer (EC), and colorectal cancer (CRC) patients, but further research is needed before advancing any solid conclusion

Summary

Introduction

Digestive cancers include cancers located in the esophagus, stomach, liver, pancreas, colon, and rectum. Their incidence and related mortality are increasing worldwide, but with some characteristic geographical differences [1]. According to the GLOBOCAN, i.e., Cancer Incidence in Five Continents, and the World Health Organization (WHO) mortality databases in 2018, the majority of new cases of digestive cancers (63%) and related deaths (65%) occurred in Asia, followed by Europe and North America. Esophageal, gastric, and liver cancers appear to be more prevalent in Asia, whereas colorectal and Microorganisms 2021, 9, 2585.

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