Association between the dietary inflammatory index and risk of lung cancer: a multi-centered case-control study

PurposeDietary factors might contribute to the risk of lung cancer by increasing the concentration of inflammatory markers. The literature-derived Dietary Inflammatory Index (DII) has been established to evaluate the inflammatory potential of diet correlated with inflammatory markers. The association between DII scores and the risk of lung cancer has been conflicting. So, in the current study, we aimed to assess the effect of pro-inflammatory dietary patterns measured with DII and the risk of lung cancer.MethodsA multi-center case-control study was carried out on 616 patients with lung cancer and 3412 healthy controls. Dietary intakes were collected using a 131-item food frequency questionnaire during a face-to-face interview. The DII scores including thirty-six nutrients were calculated after energy adjustments. Finally, the association between DII level and the risk of lung cancer was evaluated by performing a multi-variable regression method after adjusting for potential confounders.ResultsThe risk of overall lung cancer, small cell, and squamous cell carcinoma was elevated in the third tertile compared to the first tertile of the DII score, (odds ratio [OR] T3 vs. T1 of overall lung cancer = 1.38 (95% confidence interval [CI] 1.08-1.77), P trend = 0.01, OR T3 vs. T1 of squamous cell lung cancer = 1.82 (95% CI 1.02-3.24), P trend = 0.04, OR T3 vs. T1 of small cell lung cancer = 1.66 (95% CI 1.08-2.54), P trend = 0.019). However, no increase was observed in the risk of adenocarcinoma by adherence to a pro-inflammatory dietary pattern.ConclusionA positive link was found between DII and the risk of overall lung cancer, small-cell, and squamous-cell lung cancer. However, there was no association between DII and the risk of lung adenocarcinoma. Lung cancer is the most common malignancy worldwide. It is also the main cause of cancer-related mortality, responsible for 19% of cancer deaths in both genders. Most patients diagnosed with lung cancer suffer from advanced stages of the disease. This might emphasize the importance of identifying the modifiable risk factors of lung cancer.In a multicenter case-control study in Iran, we observed a significant positive association between a pro-inflammatory diet and the risk of overall, squamous cell, and small cell lung cancer.Adherence to an anti-inflammatory diet might reduce the risk of lung cancer.