Study links healthier diets to lung cancer cases in young non-smokers
USC researchers say pesticide exposure from conventionally grown produce is a hypothesis, not a proven cause, in a small study of younger lung cancer patients.
By Lucas Ferreira · Science & Environment Writer
3 min read
USC researchers reported an unexpected pattern among lung cancer patients under 50: those who had never smoked tended to report healthier-than-average diets. The team said the finding raises questions about whether pesticide exposure from some conventionally grown foods could be a factor in rising lung cancer diagnoses among younger non-smokers, especially women.
The research, from the USC Norris Comprehensive Cancer Center at Keck Medicine of USC, was presented at the annual meeting of the American Association for Cancer Research, according to University of Southern California Health Sciences. Researchers stressed that the work is preliminary and does not show that fruits, vegetables or whole grains cause lung cancer.
Jorge Nieva, a medical oncologist and lung cancer specialist at USC Norris and the study’s lead investigator, said the results point to a possible environmental risk tied to foods that are otherwise considered beneficial. The researchers said pesticide residues, rather than the foods themselves, are the suspected area for further study.
Small study examined patients diagnosed by age 50
The study is part of the Epidemiology of Young Lung Cancer Project. It included 187 people who had received a lung cancer diagnosis by age 50, according to USC Health Sciences.
Participants provided information on their diets, smoking histories, demographic backgrounds and cancer diagnoses. Most had never smoked, and many had a type of lung cancer that differs biologically from the form commonly linked to tobacco exposure, USC said.
The researchers compared participants’ diets with U.S. dietary patterns using the Healthy Eating Index, a 1-to-100 measure of diet quality. The young non-smoking lung cancer patients had an average score of 65, compared with a national average of 57, according to the university.
Participants also reported eating more of certain plant-based foods than the average U.S. adult. USC said they consumed an average of 4.3 daily servings of dark green vegetables and legumes and 3.9 servings of whole grains, compared with 3.6 and 2.6 servings, respectively, among typical U.S. adults.
Pesticide exposure remains a hypothesis
Nieva said commercially grown, non-organic fruits, vegetables and whole grains generally carry higher pesticide residues than foods such as dairy, meat and many processed products, according to USC Health Sciences. He also cited prior research showing higher lung cancer rates among agricultural workers with long-term pesticide exposure.
The study did not directly test pesticides in foods eaten by participants. Instead, the researchers estimated possible exposure using previously published data on average pesticide residues across food categories, USC said.
The team said the next stage of research will measure pesticide levels in patients’ blood or urine. That work could help assess whether particular pesticides are associated with lung cancer risk, according to USC.
Young women are a focus
Lung cancer has historically been more common in older adults, men and smokers, and the average age at diagnosis is 71, according to USC Health Sciences. Although U.S. smoking rates have fallen since the mid-1980s and overall lung cancer rates have declined, USC said diagnoses have risen among non-smokers age 50 and younger.
The university said women under 50 who have never smoked are developing lung cancer more often than men in the same age group. In the USC study, women also tended to report higher intake of fruits, vegetables and whole grains than men.
USC said a 2021 study from related young lung cancer research found that lung cancers diagnosed before age 40 include distinct subtypes compared with cancers seen in older adults. The current findings add another line of inquiry but do not establish a cause.
The research was supported by the Addario Lung Cancer Medical Institute, AstraZeneca, the Beth Longwell Foundation, Genentech, GO2 for Lung Cancer, Upstage Lung Cancer, the National Institutes of Health and the National Cancer Institute, according to USC Health Sciences.
This story draws on original reporting from ScienceDaily.