Dissecting the association between metabolic syndrome and prostate cancer risk: analysis of a large clinical cohort.

BACKGROUND A biologic rationale exists for the association between metabolic syndrome (MetS) and prostate cancer (PCa). However, epidemiologic studies have been conflicting. OBJECTIVE To evaluate the association between MetS and the odds of PCa diagnosis in men referred for biopsy. DESIGN, SETTING, AND PARTICIPANTS Patients without prior PCa diagnosis undergoing prostate biopsy were identified from a large prostate biopsy cohort (in Toronto, Canada). The definition of MetS was based on the most recent interim joint consensus definition, requiring any three of five components (obesity, elevated blood pressure, diabetes or impaired fasting glucose, low high-density lipoprotein-cholesterol, and hypertriglyceridemia). Both the individual components of MetS and the cumulative number of MetS components were evaluated. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The outcomes were PCa detection overall, clinically significant PCa (CSPC; defined as any Gleason pattern ≥ 4, >50% involvement of a single biopsy core, or more than one of three total number of cores involved), and intermediate- or high-grade PCa (I-HGPC; Gleason 7-10). Tests for trend and multivariable logistic regression analyses were performed. RESULTS AND LIMITATIONS Of 2235 patients, 494 (22.1%) had MetS. No individual MetS component was independently associated with PCa. However, increasing number of MetS components was associated with higher PCa grade (p<0.001), as well as progressively higher odds of PCa outcomes (three or more; ie, MetS) compared with no MetS components: Odds ratios were 1.54 for PCa overall (95% confidence interval [CI], 1.17-2.04; p=0.002), 1.56 for CSPC (95% CI, 1.17-2.08; p=0.002), and 1.56 for I-HGPC (95% CI, 1.16-2.10; p=0.003) in multivariable analyses. The main limitation is the retrospective design. CONCLUSIONS Although the individual MetS components are not independently associated with PCa outcomes, MetS is significantly associated with higher odds of PCa diagnosis, CSPC, and I-HGPC. There is a biologic gradient between the number of MetS components and the risk of PCa, as well as cancer grade. PATIENT SUMMARY Metabolic syndrome is a collection of metabolic abnormalities that increases one's risk for heart disease. Our study shows that an increasing degree of metabolic abnormality is also associated with an increased risk of diagnosis of overall and aggressive prostate cancer.