Poor oral health associated with a higher risk of liver cancer, study suggests
BELFAST, UK: It remains controversial whether poor oral health is independently linked to the development of gastro-intestinal cancers, because of potential confounding by smoking, alcohol consumption and poor nutrition. In order to shed light on the topic, researchers from Queen’s University Belfast in Northern Ireland have investigated the association between oral health conditions and cancer risk.
“Poor oral health has been associated with the risk of several chronic diseases, such as heart disease, stroke and diabetes,” said lead author Dr Haydée Jordão, from the Centre for Public Health at the university. “However, there is inconsistent evidence on the association between poor oral health and specific types of gastro-intestinal cancers, which is what our research aimed to examine.”
The participants self-completed a questionnaire which included information on smoking habits, alcohol consumption and diet. For the purpose of the study, participants were categorised as having poor oral health if they reported painful gingivae, bleeding gingivae or loose teeth.
The study involved 469,628 participants, of whom 4,069 developed gastro-intestinal cancer during the course of an average six years of follow-up. In 13% of these cases, the patients reported poor oral health. While no significant associations were observed on the risk of the majority of gastro-intestinal cancers and poor oral health, a substantial link was found for hepatobiliary cancer, specifically hepatocellular carcinoma. For this cancer type, the researchers found a 75% increased risk in association with poor oral health.
The biological mechanisms by which poor oral health may be more strongly associated with liver cancer, rather than other digestive cancers, are currently unclear. One explanation is the potential role of the oral and gut microbiome in disease development. “The liver contributes to the elimination of bacteria from the human body,” stated Jordão. “When the liver is affected by diseases, such as hepatitis, cirrhosis or cancer, its function will decline and bacteria will survive for longer and therefore have the potential to cause more harm. One bacterium, Fusobacterium nucleatum, originates in the oral cavity but its role in liver cancer is unclear. Further studies investigating the microbiome and liver cancer are therefore warranted.”
Another theory in explaining the higher cancer risk owing to poor oral health suggests that participants with a high number of missing teeth may alter their diet and consume softer and potentially less nutritious foods, which in turn influence the risk of liver cancer.
The study, titled “The association between self-reported poor oral health and gastrointestinal cancer risk in the UK Biobank: A large prospective cohort study”, was published online in the United European Gastroenterology Journal on 8 June 2019, ahead of inclusion in an issue.