A conference presentation (non peer-reviewed) from University of Southern California researchers has attracted attention by reporting that people diagnosed with lung cancer before age 50 who never smoked tended to report healthier diets and higher rates of past oral‑contraceptive use than the general US population.
Various news outlets have published news headlines like “eating more fruits and vegetables could put you at risk for lung cancer”. Is this myth or fact?
About lung cancer
Lung cancer is most commonly diagnosed in older adults and is strongly associated with tobacco smoking.
The average age at diagnosis is about 70. Public‑health efforts to reduce smoking have produced large falls in lung cancer mortality in the United States alone based on the report. From 2012 to 2021, new cases declined annually by around 3.0% in men and 1.4% in women.
Despite these broad declines, clinicians and researchers have noted worrying signals, an apparent rise in lung cancer diagnosed in younger adults, particularly in non‑smokers and especially women.
When lung cancer occurs before age 50 it is often termed young‑onset lung cancer. Tumours in younger non‑smokers frequently have biological features different from those linked to smoking.
What the new controversial research shows
The USC team analysed data from the Epidemiology of Young Lung Cancer study, a nationwide observational project.
The analysed group included 187 patients diagnosed with lung cancer by age 50; 78% were women. Tumours were categorised by underlying biology: an EGFR pathway group (73 patients), a fusion‑positive group (82) and a mixed‑mutations group (32).
Researchers collected self‑reported data about the year before diagnosis, including smoking history, oral‑contraceptive use and diet. Diet quality was assessed using the Healthy Eating Index (HEI), a standard score from 0 to 100 where higher values indicate greater adherence to dietary guidelines (more fruit, vegetables and whole grains).
Average HEI scores for the EGFR and fusion‑positive groups were about 65, compared with an average US adult HEI of 57. The groups also reported eating more dark green vegetables, legumes and whole grains than the general population. The majority of participants in each group reported never having smoked.
The researchers additionally reported higher lifetime use of oral contraceptives among women in the cohort: roughly 77% in the EGFR and mixed groups, and about 65% in the fusion‑positive group, compared with considerably lower reported current‑use percentages in national surveys.
These results were presented at the American Association for Cancer Research annual meeting and have not yet been peer‑reviewed.
The authors suggest pesticide residues or other environmental chemicals as possible explanations. The finding is preliminary, controversial and does not justify changing healthy eating habits.
How this might even possible
The study authors explicitly caution that they are not accusing fruits, vegetables or whole grains of causing cancer.
Two hypotheses they propose warrant further study.
Firstly, pesticide residues. Conventionally grown produce and some grains can carry pesticide residues. Some pesticides are classified as carcinogenic or are suspected carcinogens (cancer causing agent), and heavy occupational exposure has been linked to higher lung cancer rates in agricultural workers.
If people who consume large amounts of conventionally grown plant foods have higher internal exposure to particular pesticides, that might be an explanatory pathway.
Secondly, endocrine‑disrupting chemicals. Some pesticides and other environmental chemicals can interfere with hormone systems. The EGFR subtype of lung cancer is more common in women and sometimes interacts with oestrogen signalling.
Prior oral‑contraceptive use may point to hormone‑related pathways worth investigating, or it may be a marker of other behavioural or demographic differences.
Determining whether any specific chemical is involved requires measuring actual exposure in people and studying biological effects in laboratory and epidemiological work.
How strong is the evidence
The evidence is preliminary and limited:
- The study is observational and cannot establish causation.
- The sample size is modest and heavily female‑weighted, which limits generalisability.
- Diet and contraceptive histories were self‑reported for the year before diagnosis and are subject to recall bias.
- The study did not measure pesticide residues, metabolites or other chemical biomarkers; the link to pesticides and endocrine disruptors is speculative.
- Confounding factors—geography, occupation, genetic predisposition, air pollution and others—might explain the observations.
- The findings were presented at a conference and are not yet peer‑reviewed.
Together, these limitations mean the results should be treated as hypothesis‑generating, not definitive, particularly it is inconsistent with other evidence we have so far.
Why the report is controversial and how to read it
The study’s headline‑grabbing suggestion—that healthier diets or oral‑contraceptive use are linked with early‑onset lung cancer—has sparked debate.
That debate is appropriate and useful, but it should be grounded in careful interpretation.
Readers and reporters should be sceptical and consider how these findings fit with the broader evidence base.
Decades of high‑quality research support the health benefits of diets rich in fruit, vegetables and whole grains, which reduce risks of heart disease and some cancers.
Single, small observational studies that produce counter‑intuitive associations need replication and direct exposure measurement before they influence public health advice.
What this means for patients and the public
This study does not change medical or dietary guidelines. Maintain a balanced diet that includes fruit, vegetables and whole grains as recommended by public‑health authorities.
If you are concerned about pesticide residues:
- Wash fresh produce under running water using gentle friction or rubbing.
- When affordable and available, consider some organic purchases or local produce from trusted sources.
- Grow a small amount of produce at home if possible.
For people with occupational exposure to pesticides, seek guidance from occupational health services.
Treatments, prevention and policy implications
Clinically, the study does not alter lung cancer treatment or screening recommendations. From a policy perspective, the research highlights the need to broaden investigation of environmental risk factors, not abandoning existing health advice.
Robust evidence linking specific chemicals to cancer risk could justify regulatory or agricultural changes, but such policy action requires stronger and replicated evidence and careful assessment of trade‑offs in food systems.
What remains unknown
Key questions for follow‑up research;
- Are these associations reproducible in larger, independent cohorts with matched controls?
- Do young‑onset lung cancer patients carry higher levels of particular pesticide metabolites or other chemicals than controls?
- Which chemicals, if any, are implicated and at what exposure levels?
- How do genetics, air pollution, occupation, lifestyle and hormones interact to influence risk?
The USC team has indicated plans to measure pesticide biomarkers in biological samples and to explore geographic and chemical‑specific exposure patterns.
Peer review and replication will be essential next steps.
PP Health Malaysia’s Perspective
The USC study raises provocative, testable questions about environmental contributors to young‑onset lung cancer in non‑smokers, particularly women.
The evidence to date is associative and preliminary.
The sensible response is cautious scepticism — keep following established health advice, avoid knee‑jerk changes to diet, and watch for larger, peer‑reviewed studies that measure exposures directly before drawing firm conclusions.
The post News Headlines: “Eating More Fruits and Vegetables Could Put You at Risk of Lung Cancer” — Myth or Fact? first appeared on PP Health Malaysia.