The metabolic syndrome and the risk of prostate cancer under competing risks of death from other causes.

BACKGROUND: Associations between metabolic syndrome (MetS) components and prostate cancer development have not been studied comprehensively; results have been divergent. Using the National Cholesterol Education Program Adult Treatment panel III (NCEP) and International Diabetes Federation (IDF) definitions of the MetS, we investigated such associations taking competing risks of death into consideration.

METHODS: In the prospective Uppsala Longitudinal Study of Adult Men of 2,322 Caucasian men with 34 years of follow-up baseline, MetS measurements at age 50 years were used. Cumulative incidence of prostate cancer and death with/without the MetS were calculated. Competing risk of dying was taken into account by calculating the conditional probability of prostate cancer with/without the MetS.

RESULTS: Two hundred and thirty-seven prostate cancers were identified. Prostate cancer probability by age 80 years with baseline MetS compared with without MetS was nonsignificantly higher [5.2 percent units (confidence interval (CI), -0.8% to 11.3%; NCEP); 2.7 percent units (CI, -2.7% to 8.0%; IDF)]; cumulative incidence proportions of death was significantly higher [19.3 percent units (CI, 13.4-25.3%; NCEP); 15.3 percent units (CI, 9.5-21.1%; IDF)]; and conditional probability of prostate cancer considering death from other causes was significantly higher [7.3 percent-units (CI, 0.2-14.5%); odds ratio of 1.64 (CI, 1.03-2.23; NCEP)] and nonsignificantly higher [5.0 percent-units (CI, -1.6% to 11.6%); odds ratio of 1.43 (CI, 0.89-1.90; IDF].

CONCLUSIONS: The MetS by the NCEP definition is associated with prostate cancer, taking the competing risk of early death from other causes into account.

IMPACT: The results further highlight the public health effect of the increasing prevalence of MetS and the importance of considering competing risks when studying risk factors for cancer.