Younger adults with body mass indexes (BMIs) categorized as overweight and obese have an increased risk for colorectal cancer (CRC) compared against individuals with normal BMIs, according to a study in the American Journal of Gastroenterology.
Researchers performed a systematic literature search in the PubMed, EMBASE, and Web of Science databases up to February 28, 2021, for epidemiologic studies on the association of BMI (before diagnosis but not near diagnosis) with early-onset CRC (EOCRC) risk. They defined all first-time diagnoses of CRC in persons aged ≤55 years as occurring in younger adults.
A total of 12 studies were included in the systematic review, of which 6 studies with similar BMI groups were included in the meta-analysis. The 12 studies included 242,561 CRC cases, with 32,275 participants aged ≤55 years.
Among the 12 studies, 9 reported a positive association between overweight and obesity with increased EOCRC risk. All studies that included BMI during late adolescence also reported a positive association with EOCRC risk.
According to the meta-analysis, overweight and obesity (BMI ≥25 kg/m2) were associated with a 42% increased risk for CRC compared with normal weight (odds ratio [OR], 1.42; 95% CI, 1.19-1.68).
In separate meta-analyses of the associations of overweight vs normal weight and obesity vs normal weight with EOCRC risk, the investigators found a substantially stronger excess EOCRC risk for obesity (OR, 1.88; 95% CI, 1.40-2.54) compared with overweight (OR 1.32; 95% CI, 1.19-1.47). In sensitivity analyses that had a cutoff age of 50 years, similar results were observed.
The researchers noted that the diverse timing of BMI assessment, various inclusion and exclusion criteria, and different covariate adjustments limit the comparability of the findings from the included studies, and the meta-analysis was limited to 6 studies that used comparable BMI categories. Additionally, due to the limited number of studies and information available, dose-response meta-analyses could not be conducted.
“Interventions aimed at preventing and enhancing the management of obesity in adolescents and younger adults, which are crucial for the prevention of many other adverse health outcomes, might also play a key role for reducing CRC incidence in younger and older adults, and should be a public health priority,” concluded the study authors.
Li H, Boakye D, Chen X, Hoffmeister M, Brenner H. Association of body mass index with risk of early-onset colorectal cancer: systematic review and meta-analysis. Am J Gastroenterol. 2021;116(11):2173-2183. doi: 10.14309/ajg.0000000000001393