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Meta-Analysis
. 2013 Jun;24(6):1207-22.
doi: 10.1007/s10552-013-0201-5. Epub 2013 Apr 6.

Meta-analyses of colorectal cancer risk factors

Constance M Johnson  1 , Caimiao Wei, Joe E Ensor, Derek J Smolenski, Christopher I Amos, Bernard Levin, Donald A Berry
Affiliations
Meta-Analysis

Meta-analyses of colorectal cancer risk factors

Constance M Johnson et al. Cancer Causes Control. 2013 Jun.

Abstract

Purpose: Demographic, behavioral, and environmental factors have been associated with increased risk of colorectal cancer (CRC). We reviewed the published evidence and explored associations between risk factors and CRC incidence.

Methods: We identified 12 established non-screening CRC risk factors and performed a comprehensive review and meta-analyses to quantify each factor's impact on CRC risk. We used random-effects models of the logarithms of risks across studies: inverse-variance weighted averages for dichotomous factors and generalized least squares for dose-response for multi-level factors.

Results: Significant risk factors include inflammatory bowel disease (RR = 2.93, 95 % CI 1.79-4.81); CRC history in first-degree relative (RR = 1.80, 95 % CI 1.61-2.02); body mass index (BMI) to overall population (RR = 1.10 per 8 kg/m(2) increase, 95 % CI 1.08-1.12); physical activity (RR = 0.88, 95 % CI 0.86-0.91 for 2 standard deviations increased physical activity score); cigarette smoking (RR = 1.06, 95 % CI 1.03-1.08 for 5 pack-years); and consumption of red meat (RR = 1.13, 95 % CI 1.09-1.16 for 5 servings/week), fruit (RR = 0.85, 95 % CI 0.75-0.96 for 3 servings/day), and vegetables (RR = 0.86, 95 % CI 0.78-0.94 for 5 servings/day).

Conclusions: We developed a comprehensive risk modeling strategy that incorporates multiple effects to predict an individual's risk of developing CRC. Inflammatory bowel disease and history of CRC in first-degree relatives are associated with much higher risk of CRC. Increased BMI, red meat intake, cigarette smoking, low physical activity, low vegetable consumption, and low fruit consumption were associated with moderately increased risk of CRC.

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Conflict of interest statement

Disclosure of Potential Conflicts of Interest

Donald A. Berry is co-owner of Berry Consultants, LLC, a company that designs adaptive clinical trials for pharmaceutical and medical device companies and NIH cooperative groups.

Figures

Figure 1
Figure 1. Colorectal cancer (CRC) relative risk estimates by risk factor
Dose was modeled with both linear and restricted cubic splines random effects meta-regression model. All exposure levels were reference subtracted in model fitting. For the purpose of graphical illustration, 22 kg/m2 was used as the reference for BMI, the value of 1 for the standardized PA score was used as the reference for PA, and the lowest value of 0 was used as the reference for all other multi-level risk factors. CC=case-control studies, CRC=colorectal cancer, F=Female, B=mixed genders, M=Male. A. body mass index (BMI in kg/m2); B. physical activity (PA); C. cigarette smoking; D. alcohol; E. CRC family history; F. inflammatory bowel disease (IBD); G. current postmenopausal hormone therapy (HT); H. former postmenopausal hormone therapy (HT); I. aspirin/nonsteroidal anti-inflammatory drugs (NSAIDs); J. processed meat; K. red meat; L. fruit; M. vegetables
Figure 1
Figure 1. Colorectal cancer (CRC) relative risk estimates by risk factor
Dose was modeled with both linear and restricted cubic splines random effects meta-regression model. All exposure levels were reference subtracted in model fitting. For the purpose of graphical illustration, 22 kg/m2 was used as the reference for BMI, the value of 1 for the standardized PA score was used as the reference for PA, and the lowest value of 0 was used as the reference for all other multi-level risk factors. CC=case-control studies, CRC=colorectal cancer, F=Female, B=mixed genders, M=Male. A. body mass index (BMI in kg/m2); B. physical activity (PA); C. cigarette smoking; D. alcohol; E. CRC family history; F. inflammatory bowel disease (IBD); G. current postmenopausal hormone therapy (HT); H. former postmenopausal hormone therapy (HT); I. aspirin/nonsteroidal anti-inflammatory drugs (NSAIDs); J. processed meat; K. red meat; L. fruit; M. vegetables
Figure 1
Figure 1. Colorectal cancer (CRC) relative risk estimates by risk factor
Dose was modeled with both linear and restricted cubic splines random effects meta-regression model. All exposure levels were reference subtracted in model fitting. For the purpose of graphical illustration, 22 kg/m2 was used as the reference for BMI, the value of 1 for the standardized PA score was used as the reference for PA, and the lowest value of 0 was used as the reference for all other multi-level risk factors. CC=case-control studies, CRC=colorectal cancer, F=Female, B=mixed genders, M=Male. A. body mass index (BMI in kg/m2); B. physical activity (PA); C. cigarette smoking; D. alcohol; E. CRC family history; F. inflammatory bowel disease (IBD); G. current postmenopausal hormone therapy (HT); H. former postmenopausal hormone therapy (HT); I. aspirin/nonsteroidal anti-inflammatory drugs (NSAIDs); J. processed meat; K. red meat; L. fruit; M. vegetables
Figure 1
Figure 1. Colorectal cancer (CRC) relative risk estimates by risk factor
Dose was modeled with both linear and restricted cubic splines random effects meta-regression model. All exposure levels were reference subtracted in model fitting. For the purpose of graphical illustration, 22 kg/m2 was used as the reference for BMI, the value of 1 for the standardized PA score was used as the reference for PA, and the lowest value of 0 was used as the reference for all other multi-level risk factors. CC=case-control studies, CRC=colorectal cancer, F=Female, B=mixed genders, M=Male. A. body mass index (BMI in kg/m2); B. physical activity (PA); C. cigarette smoking; D. alcohol; E. CRC family history; F. inflammatory bowel disease (IBD); G. current postmenopausal hormone therapy (HT); H. former postmenopausal hormone therapy (HT); I. aspirin/nonsteroidal anti-inflammatory drugs (NSAIDs); J. processed meat; K. red meat; L. fruit; M. vegetables
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