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Study Examines Potential Link Between Diet and Lung Cancer Risk in Younger Non-Smokers

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Study Links Healthier Diet Scores to Early-Onset Lung Cancer in Non-Smokers

A preliminary study has identified an association between higher scores on a healthy diet index and early-onset lung cancer among people who have never smoked. Researchers emphasize the findings do not establish causation.

Research presented at the 2024 American Association for Cancer Research (AACR) annual meeting analyzed data from 187 patients diagnosed with lung cancer before age 50. The participants were part of the Epidemiology of Young Lung Cancer study. Approximately 78% of the study group were women, and the majority had never smoked.

Key Dietary Findings

Researchers assessed dietary habits using food-frequency questionnaires and the Healthy Eating Index (HEI), where a higher score indicates closer adherence to U.S. dietary guidelines.

  • The average HEI score among the study participants was approximately 65.
  • This is higher than the average HEI score of 57 for U.S. adults.
  • Participants reported consuming more servings of specific food groups than the national average:
    • 4.3 servings of dark green vegetables and legumes per day (national average: 3.6 servings).
    • 3.9 servings of whole grains per day (national average: 2.6 servings).

The analysis found this association between higher HEI scores and early-onset lung cancer was present in non-smokers and was particularly noted in patients whose tumors were driven by specific biological pathways (EGFR and fusion-positive).

Proposed Explanations and Context

The study authors noted the association is counterintuitive, as healthier diets are generally linked to reduced cancer risk. They proposed that environmental exposures, rather than the foods themselves, might explain the findings.

  • A hypothesis presented is that commercially produced (non-organic) fruits, vegetables, and whole grains may carry higher levels of pesticide residues compared to some other food categories.
  • The study referenced existing data showing agricultural workers with regular pesticide exposure tend to have higher rates of lung cancer.
  • The research did not directly measure pesticide levels in the foods consumed by participants but estimated potential exposure using established data on average pesticide levels in food categories.

This research arises in the context of shifting lung cancer trends. While overall lung cancer rates have declined alongside reduced smoking, researchers have observed increasing rates among younger non-smokers, particularly women. The average age of lung cancer diagnosis in the U.S. is 70 years.

Important Limitations and Next Steps

The researchers and available study details highlight several important limitations:

  • The findings show an association, not causation. The study does not prove that eating fruits, vegetables, or whole grains causes cancer.
  • The results have been presented at a conference but have not yet been published in a peer-reviewed scientific journal.
  • The study did not directly measure individuals' exposure to pesticides or other environmental chemicals.

Lead investigator Dr. Jorge Nieva stated that more research is needed to explore the potential link. Proposed next steps include:

  • Directly measuring pesticide metabolites in the blood or urine of lung cancer patients.
  • Conducting studies across different geographic regions with varying agricultural practices.
  • Investigating other environmental or chemical exposures.

Funding and Disclosures

The research is supported by multiple organizations, including the Addario Lung Cancer Medical Institute and AstraZeneca, and receives funding from the National Institutes of Health and National Cancer Institute. Dr. Jorge Nieva has disclosed receiving consulting payments from AstraZeneca and Genentech.