Preventing Head and Neck Cancers
This year, approximately 52,000 US residents will be diagnosed with head and neck cancers. Almost all are preventable.
Cancers categorized as head and neck include the mouth, tongue, nose, pharynx and larynx. These cancers are often aggressive and the treatment harsh. Alcohol and tobacco are two well-established risk factors. And AICR’s expert report and its updates show that consuming non-starchy vegetables, fruits and foods containing carotenoids lowers risk. Yet the relatively few cases of these cancers have made it challenging to examine the role of dietary factors. Now, larger emerging studies are adding to the understanding of how diet and other risk factors interact and may reduce the risk of head and neck cancers.
“The vast majority of head and neck cancers are preventable,” said Zuo-Feng Zhang, MD, PhD, an epidemiologist at the University of California Los Angeles and a leading expert on head and neck cancers. “We know the major risks. What we are seeing now are major papers in head and neck cancers that combine studies to look at what is protective in the diet … the results are quite exciting.”
Diet, Red Meat and Fruits
Two studies published this year build on the evidence suggesting a healthy diet may reduce head and neck cancer risk. A major source of the emerging data stems from the International Head and Neck Cancer Epidemiology consortium (INHANCE), on which Zhang is a committee member. The INHANCE collaboration of research groups began in 2004 and includes over 26,000 cases of head and neck cancers.
One of the studies, using data from INHANCE, found that higher consumption of fruits and vegetables lowered risk; higher red and processed meat increased risk. “Among never smokers, we found high fruit intake was protective and that was the strongest association; vegetables were also protective, ” said Mia Hashibe, PhD, an epidemiologist at the Huntsman Cancer Institute at the University of Utah and lead author of the study.
“Most of our studies in INHANCE are case control, patients knew they had the cancer and that can affect the interview,” said Hashibe. There also could still be residual effects of smoking and drinking. “We are just starting to explore cohort studies with biomarkers, and we need those to capture true dietary patterns.”
At the University of North Carolina, epidemiologist Patrick Bradshaw, PhD, and his colleagues’ analysis of data from the largest US case-control study also revealed a link between head and neck cancers and diet, with a focus on dietary patterns. “So many foods are correlated together, we wanted to get at the way people tend to eat and see how that relates,” said Bradshaw, who is also a AICR/WCRF Marilyn Gentry Fellow. “If you’re eating a diet high in fruits and vegetables like broccoli and strawberries, is it the broccoli and strawberries or is it eating them together?”
For the study, Bradshaw pulled data from approximately 2,500 participants of a North Carolina study of head and neck cancers. About half the participants were diagnosed with a cancer. He identified two major dietary patterns. Consumption of the highest amounts of fruits, vegetables and lean protein linked to a reduced risk of all types of head and neck cancer compared to those who ate the least; consumption of the highest amounts of fried foods, high-fat and processed meats, and sweets was associated with an increased risk of laryngeal cancer.
“The more you ate of the healthier dietary pattern, the higher the protection,” noted Bradshaw. The effect of the healthier dietary pattern was even more protective among African Americans, although this research needs confirmation with a larger study, he says.
Drinking and Smoking
Smoking is the major cause of head and neck cancers with alcohol close behind; together, they account for approximately three-quarters of the cancers.
With alcohol, there’s a strong dose-response relationship. “Alcohol may directly damage the oral cavity because that’s the first entrance," says Zhang. "The effect of alcohol cessation is strongest in the oral cavity, less strong in the pharynx, and even less strong in the stomach – it’s kind of distant.”
Although evidence suggests diet plays a role in head and neck cancers, the most effective way to prevent these cancers is to not use tobacco or drink alcohol. “Nutrition is very important: It’s good for the heart and overall cancer protection, but you need to stop the major risk factors first.”
Protecting against the human papillomavirus (HPV) is also important. HPV-related head and neck cancers occur mainly in the oropharynx, and it is the fastest growing type of these cancers. Add good oral hygiene to healthy lifestyle habits, says Zhang, and “head and neck cancers cancers can be largely reduced.”
Excerpted from ScienceNow.
Published on September 5, 2014