Surprising study finds healthy fruit, vegetable diet may increase risk of lung cancer in younger people

SAN CARLOS, Calif. - It sounds highly counter-intuitive, but surprising new research has found that eating a healthy diet packed with fruits, vegetables, and whole grains may lead to a greater risk of lung cancer among younger, non-smoking adults.

"Too many young people diagnosed with lung cancer are left asking, ‘how did this happen?’ especially when they have no known risk factors," said Danielle Hicks, chief patient officer and co-interim CEO of San Carlos-based GO2 for Lung Cancer, which partnered in the research project.

The study was led by researchers from the University of Southern California Norris Comprehensive Cancer Center and focused on adults 50 and younger. 

Lung cancer typically affects older adults, with data showing the average age of the disease onset at 71 years old, researchers explained, adding it also tends to affect smokers and more men than women.

Drop in lung disease, except one group 

Figures have shown that with smoking rates falling since the mid-1980’s, so have the cases of lung disease in the U.S.

"Except for one unique group — non-smokers age 50 and younger, especially women, who are now more likely to get lung cancer than men," according to a news release by the Keck Medicine of USC. 

It's a troubling trend, with figures showing about 10% of people diagnosed with the disease in the U.S. are those 55 and younger.  

Fruit, veggies, and whole grains 

The study revealed a commonality among young lung cancer patients: On average, the daily intake of fruit, vegetables and whole grains was higher than the general population.

Dig deeper:

Researchers surveyed 187 patients who were diagnosed with lung cancer by age 50. The participants provided information on their diagnosis and demographics, as well as details on their diet, and smoking history.

"Most patients had never smoked and had a form of lung cancer biologically different from lung cancer caused by smoking," Keck Medicine reported.  

As part of the research, scientists launched what they called the "Epidemiology of Young Lung Cancer Project," in partnership with the Bay Area non-profit Addario Lung Cancer Medical Institute (ALCMI).

"There is growing concern that lung cancer is biologically distinct in adults under 40, with 84% of patients carrying targetable mutations," ALCMI explained in a news release. "These historically younger patients are predominantly female and never-smokers, which raises questions about other potential environmental contributors." 

Researchers ranked the overall quality of diets based on the U.S. Department of Agriculture's Healthy Eating Index (HEI) using a scale of 1 to 100.

By the numbers:

Young non-smoking lung cancer patients scored an average HEI score of 65 out of 100. That's compared to the national average of 57, the study found.

"The finding was surprising. And we did not understand how to interpret it at first," the study’s lead researcher and lung cancer specialist with USC Norris, Dr. Jorge Nieva, told KTVU in an email.

Researchers said the counter-intuitive findings prompted them to explore potential environmental risk factors. 

Pesticides a factor

They expanded their analysis by looking into previous studies about pesticides.

"We saw the reports of elevated lung cancer rates among pesticide sprayers and thought that might be a connection," Nieva explained.

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Studies have shown non-organic, commercially produced fruits, vegetables, and whole grains are more likely to contain pesticide residue than dairy products.

There’s also evidence to suggest that agricultural workers who have been heavily exposed to those chemicals used to repel pests from crops have shown to have higher rates of lung cancer.

Researchers noted they did not test specific foods for pesticides. Instead, to estimate exposure, they used published data revealing average pesticide levels for food categories such as fruits, vegetables and grains.

Women at higher risk

Another interesting revelation from the study: Women had higher HEI scores than men, and non-smoking women also had a higher incidence of lung cancer than men.  

"Factors that may be at play in women are the high levels of hormone contraception use in our population, though it did not differ from the US averages," Nieva explained, adding, "Many pesticides are endocrine-disrupting, and we know that many of these cancers express hormone receptors." 

Pesticide exposure can play the role of a "hormone impostor" affecting the endocrine system, which can result in cancer and other adverse health outcomes.  

"The pesticides can act as endocrine disruptors that interact with estrogen receptors seen in the lung cancers most prevalent in the young lung cancer population," ALCMI researchers explained.

Environmental contributors 

Experts said the study may help determine "modifiable risk factors" among people without lifestyle behaviors historically associated with lung cancer, such as smoking.

They said the findings call for a more in-depth look into other possible environmental contributors.

"This research reflects what patients have long suspected. There may be risk factors beyond their control. It’s a critical step toward understanding risk, improving early detection, and giving patients clearer answers," Hicks said. 

Nieva said the findings lay the groundwork for necessary future analysis on the effects of pesticides and lung cancer. 

The small sample size of the study should also be noted in the argument for further research. 

What's next:

Nieva said researchers will broaden the scope to incorporate global trends in tobacco use in correlation with the disease and targeted pesticides that are consumed at higher levels by women compared to men.

"This work represents a critical step toward identifying modifiable environmental factors that may contribute to lung cancer in young adults," said Nieva. "Our hope is that these insights can guide both public health recommendations and future investigation into lung cancer prevention."  

The study included multiple other entities, including researchers from the California Northstate University College of Medicine in Elk Grove, drugmaker AstraZeneca, as well as Bay Area-based Beth Longwell Foundation and biotech company Genentech. 

Research disclosure: Nieva has received consulting payments from AstraZeneca and Genentech.  

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