USC study finds most early-onset lung cancer patients never smoked

ANBAR, Iraq — LOS ANGELES — A study led by the University of Southern California examined 187 patients diagnosed with lung cancer before age 50 and found the large majority had never smoked, with the biological profile of their tumors differing from tobacco-related disease. Researchers reported that the group ate healthier than the general population, with women in particular consuming more leafy vegetables, legumes and whole grains. The study's lead researcher, thoracic oncologist Dr. Jorge Nieva, said pesticide residue on conventionally grown fruits, vegetables and grains could be a factor in the increase observed among younger patients. The team did not directly measure pesticide residues in the foods consumed by participants; their analysis relied on previously published average data. Globally, an estimated 10 to 20 percent of lung cancer cases occur in people who have never smoked, a share that has drawn growing research attention as smoking rates decline in many countries. Researchers said larger, biomarker-based studies would be needed to identify specific environmental exposures driving early-onset disease in non-smokers.