New study finds poor oral health may increase the risk of liver cancer by 75 percent

A new large-scale UK study has found that poor oral health may be linked to an increased risk of liver cancer, building on previous research which has also linked oral health to a range of diseases.

Carried out by researchers at Queen's University Belfast, the new study looked at data on 475,766 people taken from UK Biobank -- a large long-term study which includes genomic data on more than half a million UK residents as well as data on brain imaging, their general health and medical information.

The researchers set out to investigate the association between oral health, using patients' self-reports on conditions such as painful or bleeding gums, mouth ulcers and loose teeth, and the risk of a number of gastrointestinal cancers, including liver, colon, rectum and pancreatic cancer.

The findings, published in the United European Gastroenterology Journal, showed that although there appeared to be no significant association between oral health and the risk of most of the gastrointestinal cancers included in the study, there was a strong link found for hepatobiliary (liver) cancer.

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The team also found that participants with poor oral health were more likely to be younger, female, living in deprived socioeconomic areas and consumed less than two portions of fruit and vegetables per day.

"Poor oral health has been associated with the risk of several chronic diseases, such as heart disease, stroke and diabetes," explained Dr. Haydee WT Jordão, lead author of the study. "However, there is inconsistent evidence on the association between poor oral health and specific types of gastrointestinal cancers, which is what our research aimed to examine."

Although it is still unclear how poor oral health may be associated with liver cancer, rather than other digestive cancers, one explanation is that the oral and gut microbiome may play a role in the development of the disease. "The liver contributes to the elimination of bacteria from the human body," explains Dr. 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 bacteria, 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."

The findings are not the first time oral health has been linked to a higher risk of cancer; a US study published back in 2017 also found that women who have a history of gum disease may have a higher risk of several types of cancer, particularly tumours in the esophagus and breasts.