Year: 2019
Type: review
Study designs: Systematic Review, Meta-Analysis
Abstract: Colorectal cancer (CRC) causes the mortality of more than 50 000 people per year in the United States, with CRC risk in the Americas having increased throughout the past decade (1).Numerous studies have identified that a high adult body mass index (BMI) is associated with an increased risk of CRC in adulthood, referring to inflammatory cytokines, metabolic syndrome, and diet as potential causes of CRC pathogenesis (2 -6).However, given the long induction period of carcinogenesis in the colon and rectum, early-life obesity has also been suggested to affect CRC development later in life (7).Various narrative and systematic reviews have described the impact of early-life obesity on general causes of morbidity and mortality in adulthood, but none thoroughly addressed increased risks of CRC, only providing narrative review on studies concerning the risk of CRC mortality (8, 9).The small sample sizes of individual studies that investigated the relationship between high early-life BMI and adult CRC risk ABSTRACTObjective.This meta-analysis examines the relationship between early-life obesity and risk of colorectal cancer (CRC) in adulthood. Methods.A systematic search of Google Scholar, PubMed, and reference data was conducted.Fifteen relevant studies were identified and meta-analyzed, for men and women separately.A random-effects model was used to compare the multivariable-adjusted relative risks (RR) of overall and subsite-specific CRC to the highest versus lowest categories of body mass index (BMI) in early life.Meta-regression was performed on factors that may have contributed to between-study heterogeneity.Results.High early-life BMI was associated with a 39% increased risk of CRC in adult men (RR = 1.39, 95%CI = 1.20 -1.62, P < 0.0001) and a 19% increased risk of CRC in adult women (RR = 1.19, 95%CI = 1.06 -1.35, P = 0.004).No statistically significant heterogeneity was identified in meta-regression according to tumor subsite (RR = 1.06, 95%CI = 0.97 -1.17, RR = 1.08, 95%CI = 0.99 -1.18 for male and female proximal colon cancer; RR = 1.51, 95%CI = 1.22 -1.87, RR = 1.08, 95%CI = 0.98 -1.19 for male and female distal colon cancer; and RR = 1.39, 95%CI = 1.1 -1.77, RR = 1.51, 95%CI = 0.94 -2.03 for male and female rectal cancer) or other factors, including age of BMI assessment, self-reported or measured BMI, and adjustment for smoking. Conclusions.The results suggest that high early-life BMI is associated with increased risk of CRC in adulthood.Further studies should investigate adult CRC risk in early-life obese individuals from non-Western countries and the underlying mechanisms by which early-life adiposity may influence CRC pathogenesis.
DOI: 10.26633/rpsp.2019.3
Authors: Harrison Garcia, Mingyang Song
Institution: Harvard University
Language: English
Topic: Cancer Risks and Factors
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W2906891247