The adjusted risk for lung cancer was significantly elevated in the highest group.
Adults who consumed 3.7 or more servings of ultra-processed foods per day faced a heightened risk for lung cancer vs. those who consumed less than one serving per day, according to results published in Thorax.
"To our knowledge, this study is one of the few large cohort study analyses that report an association between [ultra-processed food] consumption and an increased risk of lung cancer and its subtypes based on better capture of [ultra-processed food] intake using accurate intake assessment tools and a standardized diagnosis procedure for clinical outcomes over a relatively long follow-up period," Kanran Wang, MD, of Chongqing University Cancer Hospital, and colleagues wrote.
Using data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trials, Wang and colleagues evaluated 101,732 adults (mean age, 62.5 years; 51,545 women) to determine the impact of ultra-processed food consumption on lung cancer risk.
Researchers used the Food Frequency Questionnaire to capture each individual's dietary intakes and then categorized foods based on the four degrees of processing in the NOVA classification (unprocessed or minimally processed; containing processed culinary ingredients; processed; or ultra-processed).
"We focused on [ultra-processed foods] that include sour cream, cream cheese, ice cream, frozen yogurt, fried foods, bread, cookies, cakes, pastries, salty snacks, breakfast cereals, instant noodles and soups, sauces, margarine, candy, soft drinks, artificially sweetened fruit drinks, restaurant/industrial hamburgers, hot dogs and pizza," Wang and colleagues wrote.
The study then divided adults into four quarters using different thresholds of energy-adjusted ultra-processed food consumption. In this population, 25,433 adults fell into the lowest quarter of less than one serving of ultra-processed foods per day (mean daily serving, 0.5), 25,433 adults fell into quarter two with a serving of 1 to less than 1.8 per day (mean daily serving, 1.5), 25,432 adults fell into quarter three with a serving of 1.8 to less than 3.7 per day (mean daily serving, 3) and 25,434 adults fell into the highest quarter of at least 3.7 servings of ultra-processed foods per day (mean daily serving, 6).
The mean follow-up period in this study was 12.2 years, and in this time, researchers found 1,706 lung cancer cases (1,473 non-small cell lung cancer [NSCLC]; 233 small cell lung cancer). Notably, the number of cases was greater in the highest vs. lowest quarter of energy-adjusted ultra-processed food consumption (495 vs. 331).
To find the impact of ultra-processed food consumption on lung cancer risk, the study used a multivariable Cox regression model that adjusted for sex, age, race, family history of lung cancer, study arm, recruitment site, year of randomization, prevalent hypertension, prevalent diabetes, smoking status, alcohol consumption, Healthy Eating Index-2015 score, employment status, marital status, physical activity status and BMI.
Between adults in the highest and lowest quarter for ultra-processed food consumption, the risk for lung cancer was significantly heightened among those in the highest quarter (adjusted HR = 1.41; 95% CI, 1.22-1.6). Similarly, researchers observed significantly elevated risks for both types of lung cancer in the highest vs. lowest quarter group: NSCLC (aHR = 1.37; 95% CI, 1.2-1.58) and small cell lung cancer (aHR = 1.44; 95% CI, 1.03-2.1).
In subgroup analysis, the adjusted risk for lung cancer was greater among those in the highest vs. lowest quarter of ultra-processed food consumption across all subgroups. According to the study, these included age (younger than 65 years and 65 years or older), sex (men and women), family history of lung cancer (yes and no), BMI (less than 25 kg/m and 25 kg/m or higher), smoking status (current/former and never) and years of follow-up (less than 2 years and 2 years or higher).
Researchers also found a heightened adjusted risk for NSCLC among those in the highest vs. lowest quarter of ultra-processed food consumption across all subgroups, and the same was true when assessing the risk for small cell lung cancer.
Notably, the study described the dose-response link between energy-adjusted ultra-processed food consumption and the risk for lung cancer as non-linear. This pattern was also observed between energy-adjusted ultra-processed food consumption and the risk for NSCLC, whereas a linear dose-response pattern was found in the link between energy-adjusted ultra-processed food consumption and the risk for small cell lung cancer.
"These findings need to be confirmed by other large-scale longitudinal studies in different populations and settings. ... If causality is established, limiting trends of [ultra-processed food] intake globally could contribute to reducing the burden of lung cancer," Wang and colleagues wrote.