Eating more fruits, vegetables, and whole grains is widely recommended to improve health and reduce the risk of cancer and other diseases.
But new findings from the University of Southern California Norris Comprehensive Cancer Center, part of the Keck School of Medicine at the University of Southern California, suggest there may be unexpected risks for certain groups. A study presented at the annual meeting of the American Association for Cancer Research shows that nonsmoking Americans under age 50 who eat healthier diets may be at higher risk of developing lung cancer.
“Our study shows that young nonsmokers who consume more healthy foods than the general population are more likely to develop lung cancer,” said Jorge Nieva, MD, a medical oncologist and lung cancer expert at USC Norris and the study’s principal investigator. “These counterintuitive findings raise important questions about unknown environmental risk factors for lung cancer associated with beneficial foods that need to be addressed.”
Possible role of pesticides in lung cancer risk
Researchers believe the cause may be environmental exposures, particularly pesticides used in agriculture. Nieva says commercially produced (non-organic) fruits, vegetables and whole grains are more likely to contain higher levels of pesticide residues than dairy products, meat and many processed foods.
He also noted that agricultural workers who are regularly exposed to pesticides tend to have higher rates of lung cancer, supporting a possible link.
The study also found that young women who don’t smoke are diagnosed with lung cancer more often than men in the same age group. Women in the study also tended to eat more fruits, vegetables, and whole grains than men.
Increase in lung cancer cases among young non-smokers
Lung cancer has traditionally been associated with older people (the average age of onset of lung cancer is 71 years), people who smoke, and, historically, men.
Smoking rates have declined since the mid-1980s, leading to a decline in lung cancer cases across the United States, but one group stands out. Nonsmokers under the age of 50, especially women, now have an increased incidence of lung cancer and are more likely to develop lung cancer than men.
To better understand this trend, scientists launched the Juvenile Lung Cancer Epidemiology Project. The study included 187 patients diagnosed with lung cancer before the age of 50. Participants shared information regarding demographics, diet, smoking history, and diagnosis.
Most of these patients had never smoked. They were also diagnosed with a type of lung cancer that is biologically different from the type associated with smoking. A 2021 study by the Young Lung Cancer Epidemiology Project, the Young Lung Cancer Genomics Project, showed that lung cancer subtypes in people under 40 are different from those seen in older people.
Healthier eating scores for lung cancer patients
To assess diet quality, researchers used the Healthy Eating Index (HEI), which scores diets on a scale of 1 to 100.
The average HEI score for young non-smoking lung cancer patients was 65, compared to the national average of 57. Women in the study generally had higher HEI scores than men.
Participants also reported eating more fruits, vegetables, and whole grains than the average American. On average, they consumed 4.3 servings of dark green vegetables and legumes and 3.9 servings of whole grains each day. By comparison, the typical American adult eats 3.6 servings of dark green vegetables and legumes and 2.6 servings of whole grains per day.
More research needed on pesticides and cancer
Nieva stressed that further research is needed to confirm the link between pesticide exposure and lung cancer in young people, especially women.
In this study, the researchers did not directly measure pesticide levels in the food participants ate. Instead, they used existing data on average pesticide levels in food categories such as fruits, vegetables, and grains to estimate exposure.
Nieva said the next step is to directly measure pesticide levels in patients’ bodies through blood or urine samples. This may help determine whether certain pesticides are more strongly associated with lung cancer risk than others.
“This study represents an important step toward identifying modifiable environmental factors that may contribute to lung cancer in young adults,” Nieva said. “Our hope is that these insights will inform both public health recommendations and future research on lung cancer prevention.”
This research is supported by the Addario Lung Cancer Medical Institute, a nonprofit organization focused on advances in lung cancer research and treatment, as well as AstraZeneca, the Beth Longwell Foundation, Genentech, and GO2 for Lung Cancer and Advanced Lung Cancer.
The researchers also received funding from the National Institutes of Health (grant number R25CA225513) and the National Cancer Institute (grant number P30CA014089).
Disclosure: Dr. Nieva has received consulting fees from AstraZeneca and Genentech.
