Diabetes mellitus and risk of bladder cancer: a meta-analysis

Abstract

Aims/hypothesis Epidemiological evidence indicates that individuals with diabetes mellitus have an increased risk of several cancers. We performed a systematic review with meta-analysis to evaluate the association between diabetes and risk of bladder cancer. Methods Pertinent studies were identified by searching MEDLINE (from January 1966 to July 2006) and by reviewing the reference lists of retrieved articles. We included case-control and cohort studies reporting relative risk (RR) estimates with 95% CIs (or data to calculate them) of bladder cancer associated with diabetes. Studies of type 1 diabetes were not included. Summary RRs were calculated using a random-effects model. Results A total of 16 studies (seven case-control studies, three cohort studies and six cohort studies of diabetic patients) fulfilled the inclusion criteria. Analysis of all studies showed that diabetes was associated with an increased risk of bladder cancer, compared with no diabetes (RR=1.24, 95% CI 1.08-1.42). There was strong evidence of heterogeneity among these studies (p<0.0001). Stratification by study design found that diabetes was associated with an increased risk of bladder cancer in case-control studies (RR=1.37, 95% CI 1.04-1.80, p heterogeneity =0.005) and cohort studies (RR=1.43, 95% CI 1.18-1.74, p heterogeneity =0.17), but not in cohort studies of diabetic patients (RR=1.01, 95% CI 0.91-1.12, p heterogeneity =0.35). Conclusions/interpretation Findings from this meta-analysis suggest that individuals with diabetes may have a modestly increased risk of bladder cancer.

Cancer Risk Among People With Type 1 and Type 2 Diabetes: Disentangling True Associations, Detection Bias, and Reverse Causation

“…Our lower estimates relative to this study may be attributed to the use of national population rates as the comparator (rather than a nondiabetic population). SIR estimates for type 2 diabetes obtained in our study are also comparable to previous meta-analyses performed on sitespecific cancer incidence (4,(14)(15)(16)(17)(18)(19)(20). We add to the current literature around type 2 diabetes and cancer incidence more precise risk estimates for some of the less common cancers.…”

Glucose-lowering agents and cancer mortality rates in type 2 diabetes: assessing effects of time-varying exposure

“…There is substantial evidence indicating that patients with type 2 diabetes have an increased risk of cancer and cancer mortality [1][2][3][4][5][6]. The relationship between type 2 diabetes and various forms of cancer is biologically plausible, with insulin resistance, hyperinsulinaemia and elevated levels of IGF-1 in patients with type 2 diabetes involved in promotion of tumour cell growth [7,8].…”

Diabetes and cancer (1): evaluating the temporal relationship between type 2 diabetes and cancer incidence

“…Numerous epidemiological studies have identified associations between diabetes and several types of cancer in various populations [9][10][11][12][13][14][15][16][17][18][19] (Table 2). While the literature indicates a strong and consistent increased risk of cancer in people with type 2 diabetes, the strength of association depends on the specific cancer site.…”