March 3, 2011 -- Oral healthcare professionals can play an important role in preventing oral cancer by educating patients about oral cancer prevention strategies, including eating lots of fruits and vegetables, according to a study in the Journal of the American Dental Association (JADA, February 2011, Vol. 142:2, pp. 166-169).
"Current evidence supports a recommendation of a diet rich in fresh fruits and vegetables as part of a whole-foods, plant-based diet with limited consumption of meat, particularly processed meat," wrote Nita Chainani-Wu, DMD, PhD; Joel Epstein, DMD; and Riva Touger-Decker, PhD, in the JADA article.
In addition to discussing tobacco and alcohol use with patients (and, if relevant, betel nut and gutka consumption), as well as the risk of sexual transmission of human papillomavirus (HPV), clinicians should provide dietary advice for preventing oral cancer as part of routine patient education practices, they recommended.
Why fruits and vegetables?
Over the past 50 years, researchers have conducted more than 40 epidemiologic studies of the relationship between fruits and vegetable consumption and oral cancer risk, the JADA authors noted. A 2006 meta-analysis identified strong evidence of the protective role of vegetables and fruits, particularly citrus fruits, in the prevention of oral cancer (American Journal of Clinical Nutrition, May 2006, Vol. 83:5, pp. 1126-1134).
Similarly, a cohort study of risk factors for second primary cancers in patients with a history of oral and pharyngeal cancer (OPC), researchers at the National Cancer Institute of the National Institutes of Health found that eating fruits and vegetables has a protective effect (Nutrition and Cancer, 1994, Vol. 21:3, pp. 223-232). In another study, researchers at the School of Dentistry in San Juan, Puerto Rico, found fruit consumption to be protective against oral premalignant lesions (American Journal of Epidemiology, September 15, 2006, Vol. 164:6, pp. 556-566).
Oral cancer statistics
More than 400,000 cases of oral and pharyngeal cancer (OPC) occur annually worldwide, and OPC is among the most common cancers, according to the World Health Organization. In the U.S., approximately 36,500 new cases and 7,800 deaths resulting from OPC occurredin 2010, according to the National Cancer Institute.
More than 90% of oral cancers are squamous cell carcinomas. Prevention of these cancers in dental practice settings has focused mainly on early detection of oral premalignant mucosal changes.
According to the American Cancer Society's Guidelines on Nutrition and Physical Activity for Cancer Prevention, one-third of the more than 500,000 cancer deaths that occur in the U.S. each year can be attributed to diet and physical activity habits, including overweight and obesity.
While the mechanisms by which diet influences cancer risk are not fully understood, the JADA authors wrote, certain compounds in food may be protective against cancer. Vitamins C and E have antioxidant properties and may prevent DNA damage by reducing exposure to free radicals of oxygen. Terpenes, a group of compounds present in certain plants such as citrus fruits, can influence cell cycle progression and induce apoptosis. In addition, fruits and vegetablescontain micronutrients -- also known as phytonutrients -- that may act synergistically to prevent cancers, including OPC, the researchers noted.
Fruits, particularly berries that are high in ellagic acid, help prevent oral cancer, as do the isothiocyanates in cruciferous vegetables such as broccoli, cauliflower, cabbage, and Brussels sprouts, according to Tieraona Low Dog, MD, a clinical associate professor of medicine at the University of Arizona Health Sciences Center.
"We should all be helping our patients learn how to incorporate a minimum of five servings per day of fruits and vegetables into their diet," Dr. Low Dog told DrBicuspid.com.
In addition to cancer prevention, a growing body of data demonstrates the beneficial effects of omega-3 fatty acids, probiotics, and vitamin D for preventing periodontal disease, she added.
Other food components, such as nitrites in processed meats, which may form carcinogenic nitrosamines, may increase the risk of developing cancer, the JADA authors noted. In addition, eating salted meat, processed meat, and animal fat increases the risk of developing oral cancer. A 2008 study conducted at the Louisiana State University Health Sciences School of Public Health showed that high consumption of dairy products is a risk factor for head and neck squamous cell cancers and also has been associated with an increased risk of developing prostate cancer and ovarian cancer (Head & Neck, September 2008, Vol. 30:9, pp. 1193-1205).
Education is key
In addition to performing thorough head and neck and oral mucosal examinations to identify precancerous changes, oral healthcare professionals should educate patients about oral cancer prevention, including nutrition, the JADA authors concluded. This is particularly important for patients at an increased risk of developing OPC, including:
"I applaud the dental community for increasing the education and awareness of their professionals with regard to the importance of nutrition and oral health," Dr. Low Dog said.