Association between inflammatory potential of diet and risk of lung cancer among smokers in a prospective study in Singapore

Background Diet and inflammation have been suggested to be important risk factors for lung cancer. We examined the ability of the dietary inflammatory index-(DII (R)) to predict lung cancer in the Singapore Chinese Health Study ( SCHS). The DII is a diet quality index based on the literature linking foods and nutrients with inflammatory biomarkers. Patients and methods Using data from the SCHS for 60,232 participants, including 1851 lung cancer cases, we investigated the associations of baseline DII scores calculated from a food frequency questionnaire with risk of developing lung cancer over an average of 17.6 years of follow-up. Hazard ratios (HR) were estimated using Cox regression, adjusting for smoking status and other risk factors. Results After excluding cancers diagnosed in the first 2 years of follow-up, the DII was non-significantly associated with risk of lung cancer-(HRQ5vsQ1 = 1.13; 95% CI 0.94-1.35; P-trend = 0.24) after adjusting for age, dialect group, sex, interview year, education, body mass index, total calorie intake, physical activity and various smoking variables. In stratified analysis, stronger, statistically significant associations were evident in current smokers (HR 1.44; 95% CI 1.11-1.86; P-trend = 0.03, P for interaction = 0.003) and in male ever-smokers-(HRQ5vsQ1 = 1.37; 95% CI 1.07-1.77; P-trend = 0.03). Conclusion A pro-inflammatory diet, as shown by higher DII scores, is associated with an elevated risk of lung cancer for subjects with a history of smoking. Public health measures should be adopted to promote consumption of a healthy, antiinflammatory diet to reduce the risk of lung cancer, especially in current and former smokers.