Japanese researchers, from Aichi Cancer Center in Nagoya and Nagoya University Graduate School of Medicine have found a strong link between tooth loss and increased risk of three cancers: esophageal, head and neck, and lung. They suggest that preservation of teeth may decrease the risk of developing these diseases.

According to the researchers, bacterial infection and inflammation resulting from poor oral care that leads to tooth loss could also be driving the development of these cancers. Periodontal disease is known to increase the risk for stroke and heart disease.

“Tooth loss is a common consequence of chronic bacterial infection and may, therefore, serve as a surrogate for chronic infection and inflammation, which in turn may be important to the pathogenesis of cancer," said Akio Hiraki, PhD, the study’s lead author and researcher at the Aichi Cancer Center.

The researchers measured rates of 14 different cancers and rates of tooth loss in 5,240 cancer patients in Japan, and compared those rates with 10,480 cancer-free patients. The researchers found that patients with tooth loss were 136% more likely to develop esophageal cancer, had a 68% increased risk of developing head and neck cancer, and a 54% greater chance of developing lung cancer. The researchers also found that the rate of cancer increased proportionally to the number of teeth a patient had lost.

These increased risks were seen after researchers took into account a patient’s history of smoking and alcohol use.

The researchers say that smaller studies have linked tooth loss to different cancers, but this is the largest study to date. This is also the first study conducted within an Asian population and also the first study to show a link to lung cancer.

The researchers note that age and gender affected the associations between tooth loss and cancer risk. For head and neck and esophageal cancers, there were clear associations between tooth loss and cancer risk in women and patients younger than 70 years old, but a less clear link in men and older patients.

The researchers say that although widespread inflammation could explain the link between tooth loss and cancer risk, they note that tooth loss in the cancer patients may simply reflect unhealthy behaviors that contribute to cancer risk. Furthermore, people who have lost teeth may not be able to eat a healthy diet, and diet is also a factor in cancer development.

The researchers stress that oral care is critical to good health.

“The oral cavity is a gateway between the external environment and the gastrointestinal tract and acts in both food ingestion and digestion,” the researchers wrote. "Oral hygiene potentially affects gastrointestinal flora and nutritional status and may thus have implications for the development of chronic disease."

[Medical News Today, May 14, 2008]