Healthy Eating Index-2020 and Risk of Endometrial Cancer: A Case-Control Study Among Iranian Women

Endometrial cancer (EC) is a gynecologic malignancy with rising incidence globally, particularly in countries experiencing nutritional transitions. Diet quality may influence EC risk, yet evidence from non-Western populations remains limited. We conducted a hospital-based case-control study involving 136 histologically confirmed EC cases and 272 age- and BMI-matched controls in Tehran, Iran. Dietary intake was assessed using a validated 168-item food frequency questionnaire. Healthy Eating Index-2020 (HEI-2020) were computed to evaluate diet quality. Logistic regression was employed to estimate odds ratios (ORs) and 95% confidence intervals (CIs), controlling for reproductive factors, educational status, comorbidity, physical activity, and energy intake. Women in the highest tertile of HEI-2020 had 83% lower odds of EC compared to the lowest tertile (OR = 0.17; 95% CI: 0.09-0.30; P for trend < 0.001). The inverse association remained consistent across BMI categories and menopausal status. Greater intakes of vegetables, legumes, and plant-based proteins, along with reduced consumption of saturated fats, added sugars, and refined grains, were key dietary contributors. Greater adherence to the HEI-2020 was independently associated with reduced risk of EC among Iranian women. These findings emphasize the potential role of high-quality dietary patterns in cancer prevention and warrant confirmation in prospective studies across diverse populations.