In a large-scale population-based cohort study, researchers found a significant association between ultra-processed food consumption and increased lung cancer risk. Participants in the highest consumption quartile had a 41% elevated risk compared with those in the lowest quartile.

"Results remained statistically significant after a large range of subgroup and sensitivity analyses," noted investigators.

Key Findings

• Over more than 1.2 million person-years of follow-up, 1,706 incident lung cancer cases were identified in a dose-dependent relationship between energy-adjusted ultra-processed food intake and lung cancer incidence.

• After multivariable adjustment, participants in the highest ultra-processed food consumption quartile had a 41% increased risk for overall lung cancer compared with the lowest quartile.

• Patients in the highest quartile had a 37% increased risk for non-small cell lung cancer (NSCLC).

• The highest quartile of ultra-processed food consumption was also associated with a 44% increased risk for small cell lung cancer (SCLC).

• The association was dose-dependent and, for lung cancer and NSCLC, non-linear; for SCLC, the association was linear.

Subgroup Analysis Results

The researchers examined associations with overall lung cancer across demographic and lifestyle strata, comparing the highest to lowest quartiles of ultra-processed food consumption:

• Participants aged at least 65 years in the highest quartile had a hazard ratio of 1.52 for overall lung cancer.

• Male participants in the highest quartile had a hazard ratio of 1.65, while female participants had a hazard ratio of 1.28.

• Current or former smokers in the highest quartile had a hazard ratio of 1.34, and participants who had never smoked had a hazard ratio of 1.44.

• Participants with a BMI of at least 25 kg/m² in the highest quartile had a hazard ratio of 1.54.

Study Design and Population

The researchers used data from the PLCO Cancer Screening Trial, which enrolled participants aged 55 to 74 years between November 1993 and July 2001. The final analytical sample included 101,732 participants after exclusions for incomplete dietary data, prevalent cancer at baseline, or insufficient follow-up.

Dietary intake was assessed using the validated Dietary History Questionnaire, which captured food consumption frequency and portion sizes.

Methodological Considerations

Ultra-processed food consumption was energy-adjusted using the residual method and categorized into quartiles. Multivariable Cox proportional hazards regression models were used to estimate hazard ratios following adjustment for age, sex, race, education, smoking status, BMI, physical activity, and total energy intake. Sensitivity analyses were conducted, including exclusion of early follow-up years to account for potential reverse causation.

Study Limitations and Strengths

The authors noted that although community-based cohorts are generally more representative, the generalizability of these findings should be based on biological plausibility rather than statistical representativeness.

Strengths of the study included its large, multicenter cohort design, standardized food intake assessment, robust covariate adjustment, and long-term follow-up that enabled time-to-event analysis. However, limitations included the observational nature of the study, the potential for residual confounding, and limited racial diversity in the cohort.

Clinical Implications

The authors noted that confirmation of reducing ultra-processed food as a modifiable risk factor for lung cancer prevention in other populations and settings is warranted. "Future studies should elucidate potential molecular mechanisms and increase understanding of the observed associations," they concluded.

The authors declared no competing interests.

Source: Thorax