Abstract 7081: Body roundness index and its association with cancer incidence and mortality: prospective analyses in the UK Biobank

Abstract Background: Obesity is a well-established risk factor for cancer, yet traditional metrics like Body Mass Index (BMI) have limitations in capturing fat distribution. The Body Roundness Index (BRI) is a novel measure designed to better reflect body fat distribution and its health impacts. This study aims to explore the associations between BRI, cancer incidence, and cancer mortality, and to compare the predictive performance of BRI and BMI in assessing cancer-related risks. Methods: We utilized data from the UK Biobank to investigate the associations between the Body Roundness Index (BRI) and both cancer incidence and cancer mortality. BRI was calculated using waist circumference and height according to the following formula: BRI = 364.2 - 365.5 × √ (1 - (waist circumference / (2π)) 2/ (height / 2) 2). Cox proportional hazards models were used to evaluate the relationships between BRI and these outcomes. To evaluate the predictive capabilities of BRI and BMI for cancer outcomes, receiver operating characteristic (ROC) analysis and area under the curve (AUC) metrics were employed. The DeLong test was used to statistically compare the AUCs of BRI and BMI. Results: This study included 315, 876 participants, among whom 42, 405 (13.42%) cancer cases and 10, 519 (3.33%) cancer-related deaths were identified. The mean BRI was significantly higher in individuals with cancer incidence compared to those without (4.33 ± 1.56 vs. 4.05 ± 1.53, p < 0.05), and similarly higher in the cancer mortality group compared to the non-cancer mortality group (4.50 ± 1.62 vs. 4.08 ± 1.54, p < 0.05). Adjusting for age, sex, ethnicity, household income, education level, smoking status, alcohol consumption, physical activity, and family history of cancer, BRI showed a positive association with both cancer incidence and mortality (HR incidence= 1.04, 95% CI: 1.03 - 1.05, p < 0.05; HR mortality= 1.07, 95% CI: 1.06 - 1.09, p < 0.05). Participants were further categorized into five groups based on BRI quintiles. Compared to the lowest quintile (Q1: -0.15 to 2.81), individuals in Q4 (4.24 to 5.19) and Q5 (5.19 to 23.56) showed a 1.08-fold (95% CI: 1.05 - 1.12) and 1.15-fold (95% CI: 1.11 - 1.19) increased risk of cancer incidence, respectively, as well as a 1.09-fold (95% CI: 1.01 - 1.16) and 1.25-fold (95% CI: 1.17 - 1.34) higher risk of cancer mortality. ROC analysis revealed that BRI (AUC incidence= 0.55, AUC mortality= 0.58) outperformed BMI (AUC incidence = 0.53, AUC mortality= 0.54) in predicting both cancer incidence and mortality (p < 0.05). Conclusions: This study demonstrates that BRI is a significant predictor of both cancer incidence and mortality, outperforming BMI in predictive accuracy. These findings highlight the potential of BRI as a more effective tool for cancer risk assessment and prevention strategies. Citation Format: Wenxuan Li, Zhangyan Lyu, Mengbo Xing, Haodong Liu, Kexin Chen. Body roundness index and its association with cancer incidence and mortality: prospective analyses in the UK Biobank [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7081.