Excessive Body Fat at a Young Age Increases the Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis

Abstract

Overweight and obesity was considered as a risk factor for colorectal cancer (CRC), and CRC development may be due to exposure during one’s youth. Metabolic syndrome and insulin resistance seem to play an important role in the underlying mechanisms. Even though several studies indicated the association between BMI at young age and CRC risks, an identified founding is still lacked. Therefore, we conducted a meta-analysis and a dose-response analysis to quantify the association between BMI at young age and CRC risks with relative accuracy. We searched the PubMed, Embase, Medline and Cochrane Library databases for articles published before Sep. 15, 2019. Fifteen articles with 2 520 091 participants were included. Risk for CRC was estimated using relative risks (RR) and 95% confidence intervals (CIs). Compared with individuals with normal weight, overweight and obese young adults had a significantly higher risk of CRC (relative risks (RR):18%, 95% CI:1.08, 1.28； RR:32%, 95% CI: 1.11, 1.56, respectively). However, this correlation may not exist for obese women (RR: 1.22, 95% CI: 0.99, 1.51); Overweight may not a risk factor for rectal cancer (RC) (RR: 1.12, 95% CI: 0.97, 1.29). In the dose-response analysis, we observed a linear relationship between BMI at a young age and CRC risk, with each 1 kg/m² increment associated with a 2% increased risk. Higher BMI at a young age was positively associated with CRC risk, which indicates that weight control since a young age was needed.

Acknowledgments

We acknowledge the following corresponding authors involved for providing us additional data for analysis: Xuehong Zhang (Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA) and Terry Boyle (School of Population and Public Health, The University of British Columbia, Vancouver, BC, Canada).

Author Contributions

Lei XL conception and design of the study, acquisition of data, analysis and interpretation of data, drafting the article, final approval; Song SL acquisition of data, analysis and interpretation of data, drafting the article, final approval; Li X design of the study, revising the article, final approval; Chong G interpretation of data, final approval; Wang CH revising the article, final approval.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This article was supported by the Sichuan Science and Technology Support Project (No. 2015SZ0126).