Prospective cohort study of general and central obesity, weight change trajectory and risk of major cancers among Chinese women

Abstract

General obesity, typically measured using body mass index (BMI), has been associated with an increased risk of several cancers. However, few prospective studies have been conducted in Asian populations. Although central obesity, often measured using waist-hip ratio (WHR), is more predictive for type 2 diabetes and cardiovascular diseases (CVD) risk than BMI, knowledge of its association with cancer incidence is limited. In a cohort of 68,253 eligible Chinese women, we prospectively investigated the association of BMI, WHR and weight change during adulthood with risk of overall cancer and major site-specific cancers using multivariate Cox proportional hazard models. Compared to the BMI group of 18.5-22.9 kg/m(2) , obese (BMI ≥ 30 kg/m(2) ) women were at an increased risk of developing overall cancer (hazard ratio = 1.36, 95% confidence interval = 1.21-1.52), postmenopausal breast cancer (HR: 2.43, 95% CI: 1.73-3.40), endometrial cancer (HR: 5.34, 95% CI: 3.48-8.18), liver cancer (HR: 1.93, 95% CI: 1.14-3.27) and epithelial ovarian cancer (HR: 2.44, 95% CI: 1.37-4.35). Weight gain during adulthood (per 5 kg gain) was associated with increased risk of all cancers combined (HR: 1.05, 95% CI: 1.03-1.08), postmenopausal breast cancer (HR: 1.17, 95% CI: 1.10-1.24) and endometrial cancer (HR: 1.37, 95% CI: 1.27-1.48). On the other hand, WHR was not associated with cancer risk after adjustment for baseline BMI. These findings suggest that obesity may be associated with cancer risk through different mechanisms from those for type 2 diabetes and CVD and support measures of maintaining health body weight to reduce cancer risk in Chinese women.

Keywords: body mass index; cancer; obesity; waist-hip ratio; weight change trajectory.

© 2016 UICC.

Figures

Figure 1

Adjusted hazard ratios (HRs) for the associations of cancer risk with obesity (body mass index (BMI) ≥30 kg/m2) or per 5 kg/m2 increase in BMI* BMI group ≥ 27.5 kg/m2 was demonstrated due to a small sample size; HRs were adjusted for education, total energy intake, total vegetable and fruit intake, total meat intake, leisure-time physical activity, alcohol consumption, hormone replacement treatment, menopausal status, spouse smoking exposure, parity and family history of cancer; Women who had a hysterectomy were excluded (N = 3,487) for the endometrial cancer analysis; Women who had an oophorectomy were excluded (N = 2,693) for the ovarian cancer analysis.

Figure 2

Adjusted hazard ratios (HRs) for the associations of cancer risk per standard deviation (SD) increase in waist-hip ratio SD = 0.05; HRs were adjusted for education, total energy intake, total vegetable and fruit intake, total meat intake, leisure-time physical activity, alcohol consumption, hormone replacement treatment, menopausal status, spouse smoking exposure, parity, family history of cancer and BMI; Women who had a hysterectomy were excluded (N = 3,487) for the endometrial cancer analysis; Women who had an oophorectomy were excluded (N = 2,693) for the ovarian cancer analysis.

Figure 3

Adjusted hazard ratios (HRs) for the association of cancer risk with per 5 kg increase in weight change since age 20 years HRs were adjusted for education, total energy intake, total vegetable and fruit intake, total meat intake, leisure-time physical activity, alcohol consumption, hormone replacement treatment, menopausal status, spouse smoking exposure, parity, family history of cancer and BMI at age 20; Women who had a hysterectomy were excluded (N = 3,138) for the endometrial cancer analysis; Women who had an oophorectomy were excluded (N = 2,492) for the ovarian cancer analysis.