A conversation about pesticides and the rise of early-onset lung cancer in non-smokers, with Jorge Nieva, M.D.

Rates of early-onset lung cancer are rising among people who have never smoked, many of whom eat diets rich in fruits, vegetables, and whole grains that may carry high pesticide residues, according to recent research led by Jorge Nieva, M.D., professor of clinical medicine at the University of Southern California Norris Comprehensive Cancer Center.

In this interview with Managed Healthcare Executive, he discusses the results of the study and explains why the takeaway is not to avoid healthy foods but to wash produce and push for better research and surveillance.

Nieva recently presented the abstract ‘Dietary patterns in young lung cancer: mutation-specific environmental associations’ at the 2026 meeting of the American Association for Cancer Research.

This interview has been edited for length and clarity.

MHE: Your study shows that a diet rich in fruit, vegetables and whole grains may be tied to an increased risk of early-onset lung cancer in non-smokers. Why?

Nieva: To start this story, I'm going to bring you back to 1919 when Alton Ochsner, who's one of the pioneers of tobacco cessation in the United States and one of the first people in the United States to link smoking with lung cancer, was in medical school. At that time, a pathologist by the name of George Dock stopped the entire class at the University of Washington School of Medicine to come witness an autopsy of a lung cancer patient. He thought it was so important that the entire class see this autopsy because Dr. Dock, at the time, thought the students would never see another case of lung cancer in their career — that's how rare lung cancer was in 1919.

Fast forward to the development of machine-rolled cigarettes, and we saw an explosion of lung cancer, in large part among returning war veterans from World War One. That's when Alton Ochsner was pioneering lung cancer surgery in the United States.

The first associations between tobacco and lung cancer didn't happen until the 1940s and 1950s — that's when those first publications came out. Smoking continued to expand in the United States until about 1985, when C. Everett Koop reported that tobacco was dangerous to your health and advised smoking cessation for the entire U.S. population at that time. We saw smoking fall from its peak, and both men and women stopped smoking at the same rates.

The rates of lung cancer precipitously declined in men and did not in women, so we have to ask ourselves, 'If smoking cessation did not reduce lung cancer rates in women but did in men, what was the new carcinogen?’

Our study was an environmental exposure study among early lung cancer patients, people who had lung cancer before the age of 50. Lung cancer before the age of 50 is largely driven by mutations in genes that are not seen in tobacco-related lung cancer.

I almost never saw lung cancer in nonsmokers when I first started practicing medicine. Now about 50% of my patients are non-smokers with lung cancer, oftentimes lifelong non-smokers. There's also been a shift epidemiologically that's occurred where we now see more young women with lung cancer than young men with lung cancer, so what happened?

Our study showed that young lung cancer patients eat much healthier diets than the average U.S. population, meaning more fruits and vegetables and whole grains.

That type of diet has a much higher pesticide residue rate than a conventional U.S. diet, and it just so happens that women tend to consume a much healthier diet than men by that same metric. The typical example is a man and a woman eating lunch; the woman has a salad, and the man has a cheeseburger.

Were you surprised by the findings?

Nieva: I was, and I wasn't at the same time.

When I looked back at my young lung cancer patients, most were health-conscious people. I didn’t expect that we would find this dietary signal, but then once you saw it, it was one of those things that just made a lot of sense.

MHE: What are the implications of these early findings on things like treatment and diet recommendations?

Nieva: I don't think there's a lot that this study is going to do in terms of treatment. I can say that regarding dietary recommendations, the only thing I do different now is I wash my vegetables and fruits, which I really wasn't doing before. I certainly don't want people to get the message of ‘don't eat healthy,’ right?

Washing fruits and vegetables is easy; it's cheap and it doesn't make you lose any of the many other benefits that exist with a healthy diet. I don't think it's something in blueberries themselves, or in spinach itself, that's driving these lung cancer cases. People have been eating blueberries and spinach for years, but the amount of pesticide residue and the use of pesticides on fruits, vegetables and whole grains really has grown quite a bit since the 1980s.

MHE: What is the overall message of this study?

Nieva: The overall message is that we need to understand more about the biology of this finding. I wanted to build awareness that there really is a new epidemic. The problem is that the epidemic is not recognized because we've done such a good job with our anti-tobacco message that lung cancer cases overall are actually going down. We're not seeing that lung cancer in non-smokers is going up and is becoming an outsized fraction that shouldn't be there, and we need to understand why. I think it's the role of organizations like the Centers for Disease Control and Prevention to engage in cancer surveillance. Researchers in cancer epidemiology need to stop lumping lung cancer together as one disease and begin to recognize it as the multiple different diseases that it is and begin to epidemiologically track the different forms of lung cancer so that we really can get at an understanding of what the cause is for this shift in the lung cancer patient population and demographic, because nobody denies that this shift has occurred, but we're not going to get at the why until we recognize that it's a different disease.

We should never blame somebody's habits for developing cancer. The vast majority of smokers don't get lung cancer, and one of the sad things that I heard was lung cancer patients feeling guilty because they always ate a healthy diet and saw our study results and said, "Oh my gosh, I should have been doing something different." We love to do a lot of blaming in society and in medicine on things that cause people to be sick, and this one in particular is bothersome because you're blaming somebody for doing things that you know would have been healthy behaviors, but even for people who don't do healthy behaviors, you know, we all have our sins and foibles and things that we do that we shouldn't be doing, and I recognize that, you know, quitting smoking is hard, eating healthy can be hard, and exercise can be hard. All these things in life are hard, and everybody's got different priorities in their life, and we shouldn't not study a disease or not put effort into curing a disease if it were caused by some habit. I really do want to make sure that people don't take away that message.

MHE: What would you say to a patient who feels like their cancer is their fault?

Nieva: One, you didn't bring it on yourself; two, you still want to do healthy behaviors; and three, we're working very hard to try to find better treatments all the time. Once you already have lung cancer, we just want to focus on making sure that you're on the right treatment and that you're tolerating your treatment well. Healthy eating habits and exercise are very important in being able to sustain being on cancer treatments, so still take care of your body, because how fit you are and how well you can handle these therapies are going to go a long way to making sure that you get the most benefit out of them possible.

MHE: What are the next steps for this research?

Nieva: We are working on understanding which pesticides the people in the study were exposed to and trying to understand what those pesticides do biologically. Specifically, what they do in a type of cell called a type two pneumocyte, which is the origin cell for lung cancer in this class of patients.