Poor oral health increases liver cancer risk, study says

Poor oral health conditions, such as painful or bleeding gums, mouth ulcers, and loose teeth, may increase a patient’s risk for developing gastrointestinal cancers including liver cancer, according to new research published in the United European Gastroenterology Journal.

Researchers from Queen's University Belfast in Northern Ireland analyzed a large cohort of over 469,000 people in the United Kingdom. Of the 469,628 participants, 4,069 developed gastrointestinal cancer during the average six-year follow up. In 13 percent of these cases, patients reported poor oral health. 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.

The biological mechanisms by which poor oral health may be more strongly associated with liver cancer, rather than other digestive cancers, is currently uncertain, according to Haydée Jordão, PhD, lead author of the study. One explanation, he said, 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", said Jordão in a statement. "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, researchers said. Further studies investigating the microbiome and liver cancer are necessary, they said.

Another theory in explaining the higher cancer risk due to poor oral health suggests that participants with a high number of missing teeth may alter their diet, consuming softer and potentially less nutritious foods, which in turn influence the risk of liver cancer.

Each year in the United States, about 33,000 people get liver cancer, and about 26,000 people die from the disease, according to the Centers for Disease Control and Prevention. It is widely believed, especially in the integrative healthcare community, that up to half of cases of liver cancer are preventable, with risk factors often relating to lifestyle, such as overweight or obesity, smoking, and alcohol consumption.