The healthy eating index 2020 and colorectal cancer risk: a prospective study based on the PLCO cohort

Background – The Healthy Eating Index (HEI-2020), a metric that assesses overall diet quality based on compliance with the 2020–2025 Dietary Guidelines for Americans, has been insufficiently investigated in relation to both colorectal cancer (CRC) incidence and mortality. To address this gap, we conducted a population-based prospective study of 101, 709 U.S. adults from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, examining the associations between HEI-2020 adherence and risks of CRC incidence and death. Methods – A total of 101, 709 participants were included in this study. Dietary information was collected using the Diet History Questionnaire (DHQ), and adherence to the HEI-2020 was assessed. Higher HEI-2020 scores indicated better adherence to a healthy diet. Cox proportional hazards regression analyses were performed to examine the association between HEI-2020 scores and CRC risk. To further explore the dose–response relationship between HEI-2020 scores and CRC incidence, a restricted cubic spline (RCS) model was applied. Subgroup analyses were conducted to identify potential modifiers that might interact with HEI-2020 in relation to CRC incidence, and sensitivity analyses were performed to assess the robustness of the established association. Result – This study included 101, 709 participants, with 1, 100 incident CRC cases and 314 deaths. The fully adjusted model showed that participants in the highest HEI-2020 quartile had a lower point estimate for CRC incidence than those in the lowest quartile, although this comparison did not reach statistical significance (HR = 0.86; 95% CI: 0.73–1.02). A significant decreasing trend in CRC incidence risk was observed across HEI-2020 quartiles (P for trend = 0.021). Higher HEI-2020 scores were significantly associated with lower CRC-specific mortality (Q4 vs. Q1: HR = 0.61; 95% CI: 0.45–0.85; P for trend = 0.001), and this association remained consistent in competing-risk analyses. Site-specific analyses suggested lower risks for distal colon cancer and a borderline lower point estimate for rectal cancer, as well as a decreasing trend in proximal colon cancer mortality. Sensitivity and subgroup analyses confirmed the robustness of the findings. Conclusion – This study suggests that higher HEI-2020 scores, reflecting better alignment with the Dietary Guidelines for Americans, are associated with a significant decreasing trend in CRC incidence risk and a lower risk of CRC-specific mortality.