Is Diabetes Mellitus an Independent Risk Factor for Colon Cancer and Rectal Cancer?

Abstract

OBJECTIVES Diabetes mellitus (DM) has been associated with an increased risk of colorectal cancer (CRC). The American College of Gastroenterology Guidelines for Colorectal Cancer Screening 2008 recommend that clinicians be aware of an increased CRC risk in patients with smoking and obesity, but do not highlight the increase in CRC risk in patients with DM. To provide an updated quantitative assessment of the association of DM with colon cancer (CC) and rectal cancer (RC), we conducted a meta-analysis of case–control and cohort studies. We also evaluated whether the association varied by sex, and assessed potential confounders including obesity, smoking, and exercise. METHODS We identified studies by searching the EMBASE and MEDLINE databases (from inception through 31 December 2009) and by searching bibliographies of relevant articles. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated with fixed- and random-effects models. Several subgroup analyses were performed to explore potential study heterogeneity and bias. RESULTS DM was associated with an increased risk of CC (summary RR 1.38, 95% CI 1.26–1.51; n = 14 studies) and RC (summary RR 1.20, 95% CI 1.09–1.31; n = 12 studies). The association remained when we limited the meta-analysis to studies that either controlled for smoking and obesity, or for smoking, obesity, and physical exercise. DM was associated with an increased risk of CC for both men (summary RR 1.43, 95% CI 1.30–1.57; n = 11 studies) and women (summary RR 1.35, 95% CI 1.14–1.53; n = 10 studies). For RC, there was a significant association between DM and cancer risk for men (summary RR 1.22, 95% CI 1.07–1.40; n = 8 studies), but not for women (summary RR 1.09, 95% CI = 0.99–1.19; n = 8 studies). CONCLUSIONS These data suggest that DM is an independent risk factor for colon and rectal cancer. Although these findings are based on observational epidemiological studies that have inherent limitations due to diagnostic bias and confounding, subgroup analyses confirmed the consistency of our findings across study type and population. This information can inform risk models and specialty society CRC screening guidelines.

Self-rated health and cancer risk – a prospective cohort study among Danish women

“…Nevertheless, certain chronic diseases, e.g. diabetes, have been identified as risk factors for colon cancer [24].…”

Exploring opportunities for colorectal cancer screening and prevention in the context of diabetes self-management: an analysis of the 2010 National Health Interview Survey

“…While over 11 % of adults aged 20 years and older (25.6 million) have been diagnosed with or have undiagnosed diabetes, this figure is over 25 % for adults aged 65 years and older [2], and the prevalence of diabetes is increasing [3]. Diabetes has been linked with an increased risk of several cancers, including CRC [4][5][6]. Furthermore, diabetes has been associated with increased mortality and poorer clinical outcomes among persons with CRC [7,8].…”

Impact of Project SCOPE on Racial/Ethnic Disparities in Screening Colonoscopies

“…In addition to insurance, other covariates such as age, gender, smoking, diabetes mellitus, obesity, aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), and personal and family history of colonic neoplasia have been identified as a risk factor for colonic neoplasia [15][16][17][18][19][20][21][22][23]; therefore, these covariates were also abstracted from the medicals records. Smoking history and family history of colonic neoplasia were self-defined in the medical records.…”