• College of Health, Health Promotion and Health Behavior Program, Oregon State University, Corvallis, OR, USA; Department of Population Health, Section for Health Equity, NYU Grossman School of Medicine, New York, NY, USA.
• College of Sciences, Department of Statistics, Oregon State University, Corvallis, OR, USA.
• Division of Oncological Sciences, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA.
• Linus Pauling Institute, Oregon State University, Corvallis, OR, USA.
• College of Health, Nutrition Program, Oregon State University, Corvallis, OR, USA. Electronic address: yumie.takata@oregonstate.edu.

BACKGROUND & AIM: Current evidence on prospective associations between dairy product, dairy fat and lactose intakes and lung cancer risk is limited and inconsistent. We conducted a prospective analysis of associations of lung cancer risk with dairy product intakes in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) cohort.

METHODS: Pre-diagnostic dairy product intake was assessed through a validated Diet History Questionnaire. All incident lung cancer cases were pathologically verified. Multivariable Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for associations of lung cancer risk with intakes of total, full-fat, low-fat dairy, fermented or non-fermented dairy products; milk fat content preference; and intakes of total and saturated fats and lactose from dairy products.

RESULTS: Among 101,709 adults (mean age of 65.5 years), a total of 1583 lung cancer cases were identified during 1,167,239 person-years of follow up. Mean total dairy product intake was 156 g/1000 kilocalories (kcal), including 20 g/1000 kcal from fermented dairy products. Total dairy intake was not associated with lung cancer risk (HR [95% CI] = 1.03 [0.89-1.18]) comparing the highest quartile with the lowest. Fermented dairy intake was inversely associated with lung cancer risk (0.85 [0.72-0.99]). In contrast, there were no statistically significant associations with low-fat, full-fat or non-fermented dairy product intakes. The preference of whole milk when consuming milk as beverage was associated with a higher risk of lung cancer than the preference of <0.5% fat milk (1.24 [1.03-1.49]). Total fat, saturated fat and lactose intakes from dairy products each were not associated with lung cancer risk.

CONCLUSIONS: Our results suggest an inverse association of lung cancer risk with fermented dairy intake and a positive association with the whole milk preference in a US population. Future studies exploring underlying molecular mechanisms are warranted.