Variety in Fruit and Vegetable Intake Linked to Lower Lung Cancer Risk in Smokers

 Variety in fruit and vegetable intake is linked to lower lung cancer risk in smokers, according to the results of a prospective cohort study reported online August 31 in Cancer Epidemiology, Biomarkers & Prevention.

"We investigated whether a varied consumption of vegetables and fruits is associated with lower lung cancer risk in the European Prospective Investigation into Cancer and Nutrition study," write Frederike L. Büchner, from National Institute of Public Health and the Environment (RIVM), Bilthoven, the Netherlands, and colleagues. "...None of the [previous] studies on fruit and vegetable consumption and lung cancer risk evaluated a potential role of the diversity in fruit and vegetable consumption. Different fruits and vegetables contain many different bioactive compounds."

Lung cancer was diagnosed in 1613 of 452,187 participants with complete information, after a mean follow-up of 8.7 years. Variety in fruit and vegetable intake was quantified with diet diversity scores (DDS), and multivariable proportional hazards models allowed evaluation of the associations between DDS and lung cancer risk. Smoking status behavior and total fruit and vegetable consumption were accounted for in all models.

As variety in vegetable subgroups increased, the risk for lung cancer decreased (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.64 - 0.94 highest vs lowest quartile; P for trend = .02). However, this inverse association was observed only in current smokers (HR, 0.73; 95% CI, 0.57 - 0.93 highest vs lowest quartile; P for trend = .03). Risks for squamous cell carcinomas in current smokers were lower with more variety in fruit and vegetable products combined (HR for 2 products, 0.88; 95% CI, 0.82 - 0.95), vegetable subgroups (HR for subgroup, 0.88; 95% CI, 0.79 - 0.97), vegetable products (HR for 2 products, 0.87; 95% CI, 0.79 - 0.96), and fruit products (HR for 2 products, 0.84; 95% CI, 0.72 - 0.97), based on continuous analyses.

"Variety in vegetable consumption was inversely associated with lung cancer risk among current smokers," the study authors write. "Risk of squamous cell carcinomas was reduced with increasing variety in fruit and/or vegetable consumption, which was mainly driven by the effect in current smokers."

Limitations of this study include possible residual confounding by smoking, although the investigators paid special attention to control for smoking behavior.

"Independent from quantity of consumption, variety in fruit and vegetable consumption may decrease lung cancer risk," the study authors conclude. "...The greater variety in fruit and/or vegetable consumption was not related to lung cancer risk in former and never smokers nor was it related to the risk of adenocarcinomas and small cell carcinomas. Because smoking is the predominant risk factor, the primary focus for public health in reducing lung cancer incidence should continue to be smoking prevention and cessation."