Preliminary research from USC Norris Comprehensive Cancer Center, presented at the American Association for Cancer Research (AACR) annual meeting, found that non-smokers diagnosed with lung cancer before age 50 reported eating more fruits, vegetables and whole grains—and had higher overall Healthy Eating Index scores—than the U.S. population average. The researchers emphasized that the results do not prove diet causes lung cancer and said a possible explanation could involve environmental exposures such as pesticides, a hypothesis that requires direct testing.
Researchers from USC Norris Comprehensive Cancer Center, part of Keck Medicine of USC, analyzed survey data from 187 people diagnosed with lung cancer before age 50 in the Epidemiology of Young Lung Cancer Project.
Most participants reported they had never smoked, and the group was described as having lung cancers that differ biologically from those typically linked to smoking. The work also cited earlier project findings published in 2021 suggesting that lung cancer subtypes seen in people under 40 differ from those in older adults.
To compare participants’ eating patterns with national benchmarks, the researchers used the Healthy Eating Index (HEI), a 1–100 measure of overall diet quality. In this sample, the average HEI score was 65, compared with a U.S. average of 57, and women generally had higher HEI scores than men.
Participants also reported eating more produce and whole grains than the average U.S. adult. The study reported an average of 4.3 daily servings of dark green vegetables and legumes among participants versus 3.6 nationally, and 3.9 daily servings of whole grains versus 2.6 nationally.
Jorge Nieva, MD, a medical oncologist at USC Norris and the study’s lead investigator, called the pattern “counter-intuitive” and said it raises the possibility that an environmental factor associated with otherwise healthful foods could be contributing to risk in this young, non-smoking population. “Our research shows that younger non-smokers who eat a higher quantity of healthy foods than the general population are more likely to develop lung cancer,” Nieva said, while stressing the need for additional evidence.
Nieva and colleagues highlighted pesticides as a hypothesis, arguing that conventionally grown (non-organic) fruits, vegetables and whole grains may carry higher pesticide residues than some other food categories. Nieva also pointed to research linking regular occupational pesticide exposure to higher lung cancer rates among agricultural workers as a clue worth investigating further.
The researchers noted that they did not directly measure pesticide exposure in participants or test the specific foods they ate. Instead, they estimated exposure using published data on average pesticide levels in broad food categories. Nieva said a next step would be to measure pesticide levels directly in patients’ blood or urine to better assess whether particular chemicals are associated with risk.
The presentation also described broader epidemiologic trends: while overall U.S. lung cancer incidence has declined alongside falling smoking rates, lung cancer in younger non-smokers—particularly women—has drawn increasing attention from researchers.
According to the research team’s disclosure statement, the work was supported by the Addario Lung Cancer Medical Institute and several other organizations, and also received U.S. federal grant support (including National Institutes of Health and National Cancer Institute grants). Nieva disclosed consulting payments from AstraZeneca and Genentech.
