Association of fat quality index with head and neck cancer risk: results from a prospective study.

Background: As head and neck cancer (HNC) incidence rises, prevention demands attention to diet. Yet most studies emphasize total fat intake while overlooking fat quality. To address this gap, we examined the association between fat quality index (FQI) and HNC risk. Methods: A total of 98,560 participants were included in this study. Hazard ratios (HR) with 95% CIs for overall HNC were estimated using multivariable Cox models. Site-specific analyses were conducted, and fatty-acid components were evaluated. Effect modification was tested across prespecified subgroups. A joint analysis combined FQI tertiles with percent energy from fat. Robustness was assessed through multiple sensitivity analyses. Results: Over a median 8.8 years, 267 HNC cases occurred. Higher FQI significantly reduced overall HNC risk (fully adjusted HR for Quartile 4 vs. Quartile 1: 0.62; 95% CI, 0.42-0.91; P-trend = 0.011), demonstrating a linear inverse dose-response. Findings were consistent across subgroups and sensitivity analyses. By subsite, associations were strongest for laryngeal cancer (HR for Q4 vs. Q1: 0.43; 95% CI: 0.21-0.88). The joint analysis revealed that higher FQI was associated with lower HNC risk even among individuals with high total fat intake (HR = 0.36; 95% CI: 0.21-0.59), with no significant interaction observed. Higher Monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) intakes were inversely associated with HNC, whereas Saturated fatty acids (SFA) and Trans fatty acids (TFA) were not. Conclusion: Higher FQI is associated with lower HNC incidence, independent of total fat intake. These findings highlight that prioritizing dietary fat quality over quantity may be a critical strategy for HNC primary prevention.