Dietary Inflammatory Index and Head and Neck Cancer: A Multicenter Case-Control Study in Iran

Background: The inflammatory potential of diet may affect carcinogenesis. This study aimed to determine the association between dietary inflammatory index (DII) and the risk of head and neck cancer (HNC), as well as the interaction between DII and cigarette smoking in HNC development within the Iranian population. Study Design: This is a case-control study. Methods: In this multicenter case-control study, participants’ dietary intake was assessed using a validated 130-item food frequency questionnaire, from which DII was computed. The study recruited 876 new cases from referral hospitals across 10 provinces and 3409 healthy controls who were frequency-matched based on age, gender, and residential place. Logistic regression was used to obtain odds ratios (ORs) for HNC across tertiles of DII, which were adjusted for confounding variables. Results: A higher pro-inflammatory diet was associated with an increased risk of all HNC (OR T3 vs. T1 [95% CI]: 1.31 [1.06, 1.62]; P-trend = 0.013). There was a significant association between lip and oral cavity cancers and DII (OR T3 vs. T1 [95% CI]: 1.56 [1.16, 1.66]; P-trend = 0.004). Furthermore, an inflammatory diet was associated with an increased risk of pharynx cancer (OR T3 vs. T1 [95% CI]: 2.08 [1.14, 3.79]; P-trend = 0.02). Additionally, no significant association was observed between DII and larynx cancer, while an interaction was found between DII and tobacco use on the risk of HNC (OR T3 vs. T1 [95% CI]: 2.52 [1.78, 3.57]; P-interaction = 0.03). Conclusion: DII was positively associated with HNC risk. There was a significant association between DII and the risk of lip, oral cavity, and pharynx cancers. Additionally, there was an interaction between tobacco use and DII in determining the risk of HNC.