Combined association of general and central obesity with incidence and mortality of cancers in 22 sites

Abstract

Background: Body mass index (BMI) and waist circumference (WC) are measures of general and central obesity, respectively, and both have been shown to be associated with cancer. However, there is insufficient evidence of their combined association with the risk of cancer.

Objectives: This study aimed to investigate the associations of combinations of BMI and WC with cancer at 22 sites.

Methods: A total of 386,101 (54.5% women) UK Biobank participants aged from 37 to 73 y were included. The outcomes were incidence of and mortality from cancer at 22 sites. Participants were categorized as normal weight (BMI 18.5-24.9) or overweight (including obese, BMI ≥ 25) and as normal WC or centrally obese (WC ≥ 94 cm for men and ≥80 cm for women). Four mutually exclusive groups were derived: 1) normal weight without central obesity, 2) normal weight with central obesity, 3) overweight without central obesity, and 4) overweight with central obesity. We used Cox proportional hazards models to estimate HRs and 95% CIs.

Results: The mean follow-up period was 8.8 y. Compared with participants with normal weight and WC, men who were overweight and centrally obese had higher cancer incidence risk at 3 sites [stomach (HR: 1.75; 95% CI: 1.33, 2.32; Padj = 0.002), kidney (HR: 1.45; 95% CI: 1.17, 1.81; Padj = 0.016), and colorectal (HR: 1.31; 95% CI: 1.17, 1.47; Padj < 0.001) cancer]. Similar associations were found at 4 sites in women [endometrial (HR: 2.48; 95% CI: 2.06, 2.98; Padj < 0.001), uterine (HR: 2.23; 95% CI: 1.89, 2.64; Padj < 0.001), kidney (HR: 1.84; 95% CI: 1.37, 2.46; Padj = 0.001), and breast (HR: 1.24; 95% CI: 1.16, 1.32; Padj < 0.001) cancer] and for all-cause cancer (HR: 1.07; 95% CI: 1.03, 1.10; Padj = 0.003). Only endometrial cancer mortality (HR: 3.28; 95% CI: 1.77, 6.07; Padj = 0.004) was significantly associated with being overweight and centrally obese.

Conclusions: The combination of general and central obesity was associated with a higher risk at several cancer sites and some associations were sex-specific.

Keywords: body mass index; cancer; obesity; sex; waist circumference.