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

Abstract

Aims/hypothesis. The association of diabetes mellitus with prostate cancer has been controversial. This study examines the strength of this association by conducting a detailed meta-analysis of the studies published in peer-reviewed literature on the subject. Methods. A comprehensive search for articles published up to 2003 was performed, reviews of each study were conducted and data were abstracted. Prior to meta-analysis, the studies were evaluated for publication bias and heterogeneity. Pooled relative risk (RR) was calculated using the random-and the fixedeffects models. Subgroup and sensitivity analyses were also performed. Results. We included 14 studies, published between 1971 and 2002, in the meta-analysis (five case-control studies, nine cohort studies). We found no evidence of publication bias (p=0.89) or heterogeneity among the studies (p=0.38). The association of diabetes with prostate cancer was statistically significant, both on the basis of a random-effects model (RR=0.91, 95% CI: 0.86 to 0.96), and on the basis of a fixed-effects model (RR=0.91, 95% CI: 0.88 to 0.94). When the analysis was stratified into subgroups according to study design, the association was inverse in both cohort and case-control studies, but only in the former was it statistically significant. The sensitivity analysis strengthened our confidence in the validity of this association. Conclusions/interpretation. Our meta-analysis findings provide strong evidence that people with diabetes have a significant decrease in risk of developing prostate cancer. There is biological evidence to support this association.

Diabetes and the risk of prostate cancer: the role of diabetes treatment and complications

“…Although this result was not statistically significant, this decrease is consistent with (although slightly larger than) results from a meta-analysis of 14 studies (RR 0.91, CI 0.86-0.96). 6 We found that men with diabetes who used insulin had a 51% decreased risk of prostate cancer, With the following exception, o5% of data were missing and there was o1% difference in missing data between diabetic and non-diabetic men for any given characteristic: income (15.5% missing for non-diabetic men, 16.3% missing for diabetic men). b Coronary artery disease defined as history of heart attack, coronary bypass surgery, angioplasty or physician-diagnosed angina.…”

“…6 Of the 14 studies in the meta-analysis, two found significantly decreased risk, six found non-significantly decreased risk and none reported a significant positive association. 6 Four of six studies published subsequently 3-5,7-9 also reported a significantly decreased risk of prostate cancer among diabetic men, with approximately a 30-40% reduction in risk. [3][4][5]7 Although there appears to be a growing consensus based on epidemiologic studies that diabetes is associated with a decreased risk of prostate cancer, both the meta-analysis and individual studies of this association leave many questions unanswered.…”

“…[1][2][3][4][5][6][7] A meta-analysis of 14 studies published before 2003 found a small but significant decreased risk (relative risk 0.91, 95% confidence interval (CI) 0.88-0.94). 6 Of the 14 studies in the meta-analysis, two found significantly decreased risk, six found non-significantly decreased risk and none reported a significant positive association. 6 Four of six studies published subsequently 3-5,7-9 also reported a significantly decreased risk of prostate cancer among diabetic men, with approximately a 30-40% reduction in risk.…”

Diabetes mellitus, hyperglycaemia and cancer

“…Taking as a reference the subjects in the 2 nd and 3 rd quartiles of FPG (4.2 and 5.2 mmol/l), in both sexes subjects having diabetes at inclusion (FPG ≥ 7.0 mmol/l) had a significantly increased risk for incident cancer and, combining men and women, a significantly increased risk for liver cancer and gall bladder and bile duct cancer (Table 4) [18]. [19,20] A first, well conducted meta-analysis which included 14 studies (9 cohort studies and 5 casecontrol studies) published between 1971 and 2002, showed a slight but significant reduction of risk to develop prostate cancer in diabetic patients, with a relative risk of 0.91 (0.85-0.98) for the five cohort studies and 0.92 (0.70-1.22) for the nine case-control studies [19]. This result was confirmed by a second meta-analysis [20] which included 19 studies, 12 of which were included in the first meta-analysis: the relative risk was 0.84 (0.76-0.93).…”

Diabetes Mellitus and HbA1c Levels Associated with High Grade Prostate Cancer

“…An inverse association of diabetes with prostatic cancer has been noted in several studies, which may be due to reduced testosterone levels in diabetes, altered insulin and leptin concentrations, statins and metformin use, and changes in diet and lifestyle in controlling diabetes (Kasper and Giovannucci, 2006;Avci et al, 2013;Fall et al, 2013;Demir et al, 2014). Several studies have reported decreased PCa risk among those with DM, and others found either no protective effect or even an elevated risk (Bonovas et al, 2004;Gong et al, 2006;Leitzmann et al, 2008;Hong et al, 2011;Wu et al, 2011;Long et al, 2012 lower risk of developing prostate cancer. In addition, the mechanism through which DM and prostate cancer are related has not been fully elucidated.…”