Glycemic Index May Influence Lung Cancer Risk
Diets with high amounts of simple carbohydrates appear to increase the risk of lung cancer, especially among people who have never smoked.
Scientists have discovered a surprising risk factor for lung cancer – one that begins at the breakfast table.
A recent study published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, showed that people whose diets had a high glycemic index (GI) – a measure of carbohydrates’ effect on blood glucose levels – had a higher relative risk of developing lung cancer than those whose diets had a low GI.
The risk was more pronounced for people who had never smoked.
Lung cancer is the second most commonly diagnosed cancer in the United States, with more than 225,000 cases diagnosed in 2019, according to the National Cancer Institute. The average five-year survival rate is just 19.4 percent.
Smoking is by far the biggest risk factor, implicated in 90 percent of lung cancer cases. Among nonsmokers, previous research has suggested that environmental factors like radon or asbestos exposure may cause the disease.
“Although smoking is a major, well-characterized risk factor for lung cancer, it does not account for all the variations in lung cancer risk,” said the study’s senior author, Xifeng Wu, MD, PhD, professor and chair of Betty Marcus Cancer Prevention in the Department of Epidemiology at The University of Texas MD Anderson Cancer Center. “This study provides additional evidence that diet may independently, and jointly with other risk factors, impact lung cancer etiology.”
Study participants who had never smoked but ate the highest-GI diets were more than twice as likely to develop lung cancer as the “never smokers” who ate the lowest-GI diets. Foods with high GIs include white bread, cereal, bagels, and pasta. Foods with lower GIs include dried beans and legumes, all non-starchy vegetables, some starchy vegetables like sweet potatoes, most fruit, and many whole-grain breads and cereals, according to the American Diabetes Association.
Previous studies have investigated the association between GI and colorectal, stomach, and pancreatic cancers, but there has been limited research into the association with lung cancer.
Stephanie Melkonian, PhD, a postdoctoral fellow in Wu’s group and lead author of the study, said one possible explanation for the connection between GI and lung cancer is that diets high in GI result in higher levels of blood glucose and insulin, which promote glucose intolerance and insulin resistance. In turn, insulin resistance has been associated with changes in the body’s insulin-like growth factors, which play a role in cell proliferation and differentiation in cancer, according to previous research.
GI has become a frequently used tool in the prevention and management of diabetes. Wu said that if the results of this study are confirmed, health care providers could encourage their patients to also consider glycemic index as a factor in lung cancer prevention.
There could also be some immediate implications for the way we eat.
“The results from this study suggest that, besides maintaining healthy lifestyles, reducing the consumption of foods and beverages with high glycemic index may serve as a means to lower the risk of lung cancer,” Wu said.