LAUSR

1723 F indings from the population-based, case-control COLDENT study suggest that periodontal disease may increase the risk of sporadic colorectal cancer (CRC). The findings were published in the journal Cancer Causes & Control.1 According to the study’s coauthor, Elham Emami, DDS, MSc, PhD, dean and professor of dental medicine and oral health sciences at McGill University in Montreal, Quebec, Canada, CRC is an important cause of morbidity and mortality in Canada and throughout the world, and its public health burden is significant. “The etiology of CRC is widely recognized as being multifactorial, and previous research has suggested that modification of environmental and lifestyle factors can lead to important changes in cancer risk,” she says. “Thus, identification of modifiable risk factors that could serve as targets for preventive interventions is a public health priority. One such emerging risk factor for CRC is poor oral health.” Dr. Emami says that the potential carcinogenic effects of compromised oral health could be operating through 3 distinct mechanisms: an increased systematic inflammatory response to periodontal disease, a nutritional deficit resulting from tooth loss, and the action of “keystone” pathogens such as Fusobacterium nucleatum. “Although previous research has suggested a link between compromised oral health and CRC, the causal nature of this association remained speculative,” Dr. Emami explains. “Therefore, there was a need for well-designed epidemiological studies to properly investigate the role of poor oral health/ periodontal disease in the etiology of CRC. Poor oral health, periodontal disease, and F nucleatum infections are subject to prevention and treatment, and could thus represent important modifiable targets for public health and clinical intervention strategies aimed at the prevention of CRC. This research represents the first case-control study specifically designed to investigate the impact of oral health on CRC risk.” Dr. Emami said that the study was designed in 2009 during her postdoctoral studies. “It builds on the collaboration of a PanCanadian interdisciplinary expert research team including oral health scientists, epidemiologists (with particular expertise in cancer and nutritional epidemiology), microbiologists, molecular biologists, geneticists, dental specialists, colorectal surgeons, and oncologists,” she says. “We spent 2 years designing the study and writing the protocol. Then, during the following 3 years, we conducted a pilot study assessing the feasibility of this research project and proceeded with an initial phase based on funding from the Cancer Research Society. We then secured additional funds to conduct the full study and analyze the data. The project provided a rich resource for research–capacity building in the fields of oral health and cancer epidemiology and has served as an interdisciplinary training opportunity for graduate students.” A total of 348 incident cases of colon or rectal cancer and 310 age and sex frequency–matched controls from the Montreal Island and Laval populations participated in the study. Data were collected on periodontal disease and on several CRC risk factors via validated questionnaires. The results showed that the rate of new diagnoses of CRC in persons with a positive history of periodontal disease was 1.45 times higher than the rate in those with a negative history of periodontal disease with adjustments made for the following: age; sex; body mass index; education; income; diabetes; family history of CRC; regular use of nonsteroidal anti-inflammatory drugs; lifetime cumulative smoking; lifetime consumption of red meats, processed meats, and alcoholic drinks; and lifetime total physical activity score (adjusted relative risk, 1.45; 95% CI, 1.04-2.01; P = .026). “Our results support the association between periodontal disease and the risk of sporadic colorectal cancer. They also justify the results of our recent meta-analysis on the role of F nucleatum in colorectal cancer,” says Dr. Emami. “We anticipate that the evidence produced by our study will considerably advance the understanding of the etiology of CRC and will serve the development of preventive strategies aimed at reduction of the huge public-health burden caused by CRC in Canada and worldwide. Our findings also raise awareness about the importance of oral health and its impact on general health. It encourages public-health programming and effective clinical practice guidelines.” “This article adds to the growing list of data that shows that oral health is an important surrogate for many clinical outcomes including cardiovascular health and cancer,” adds Eric S. Christenson, MD, instructor of oncology–gastrointestinal malignancies at Johns Hopkins Hospital in Baltimore, Maryland, who was not involved with the study. “However, despite controlling for many variables, it is hard to know that exact mechanism of a link between these components. Certainly, the gut microbiome is increasingly understood to play an important role in cancer formation and treatment outcomes, which may serve as a link between these 2 phenomena [periodontal disease and colon cancer] through the constant bathing of the gut with inflammatory oral microbes. Further animal models or controlled studies with regimented dental regimens would help adjudicate causality.”