[Predictive value of different obesity indicators for colorectal cancer in different sex populations]

Objective: To investigate the predictive value of different obesity indicators for colorectal cancer (CRC) risk in different gender populations. Methods: This observational study was conducted within the Kailuan Study (Registration Number: ChiCTR-TNC-11001489). From July 2006 to October 2007, a total of 101,510 employed and retired individuals underwent health examinations, including gastrointestinal disease screening, hematological tests, and questionnaires, at Kailuan General Hospital and its 10 affiliated hospitals. After excluding those with incomplete data, 93,606 participants were included in this study and divided into male (74 852) and female (18 754) groups. CRC incidence was collected through physical examinations and questionnaires every two years. Each participant's follow-up period began at the time of the questionnaire and ended upon CRC diagnosis, death, or December 31, 2021. Body Mass Index (BMI), waist circumference, waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) were quartiled (Q1, Q2, Q3, Q4), with Q1 serving as the control group. After adjusting for traditional risk factors such as age, total cholesterol, triglycerides, diabetes, hypertension, smoking status, alcohol consumption, and physical exercise, Cox regression models were used to calculate the correlations between BMI, waist circumference, WHR, WHtR, and CRC incidence in both male and female populations. Results: The age of all patients was (51±12) years, BMI was (25.06±3.49) kg/m², waist circumference was (86.94±9.97) cm, hip circumference was (97.30±8.81) cm, WHR was 0.89±0.07, and WHtR was 0.52±0.06.Female participants had significantly lower BMI, waist circumference, WHR, and WHtR compared to males, with statistically significant differences (all P<0.05). The mean follow-up duration for all participants was 15.01 (14.10±2.66) years, during which 718 CRC cases were identified, including 626 males (0.83%) and 92 females (0.49%). Cox proportional hazards models for males showed that CRC risk increased with waist circumference from Q3 (HR=1.43, 95%CI: 1.13-1.79, P=0.003) to Q4 (HR=1.45,95%CI: 1.14-1.82, P=0.002). Similarly, CRC risk increased with WHR from Q3 (HR=1.22, 95%CI: 1.01-1.53, P=0.007) to Q4 (HR=1.43, 95%CI: 1.14-1.79, P=0.002) and with WHtR from Q3 (HR=1.37, 95%CI: 1.08-1.74, P=0.009) to Q4 (HR=1.68, 95%CI: 1.33-2.12, P<0.001). For females, CRC risk increased with waist circumference from Q2 (HR=2.37, 95%CI: 1.20-4.67, P=0.012) to Q3 (HR=2.42, 95%CI: 1.21-4.84, P=0.013) but decreased in Q4 (HR=2.08, 95%CI: 1.02-4.25, P=0.043). CRC risk increased significantly with WHR from Q2 (HR=2.20, 95%CI: 1.11-4.39, P=0.024) to Q3 (HR=2.89, 95%CI: 1.48-5.67, P=0.002) in females but was not statistically significant in Q4 (P=0.074). Among females, CRC risk also increased significantly with WHtR in Q2 (HR=2.30, 95% CI: 1.16-4.56, P=0.017) and Q4 (HR=2.64, 95%CI: 1.32-5.29, P=0.006). There were no statistically significant differences in CRC risk associated with BMI in either male or female populations (both P>0.05). Conclusion: Waist circumference, WHR, and WHtR were better predictors of CRC risk than BMI in both male and female populations.