Metabolic syndrome and prostate cancer
Background. The association between metabolic syndrome (MetS) and prostate cancer, two major public health problems, carries with it potentially significant implications. Chronic inflammation, which correlates with MetS, might also promote cancer growth. The related data remain controversial. We aimed to help solve the debates using a prospective study in Taiwan.
Methods. This dissertation contains three separate parts related to MetS and prostate cancer. Part I is a literature review on the interested association. Part II is a case-cohort study that tested the hypothesis if the MetS (WHO-criteria) altered risk of prostate cancer death using a health screening population of 54,751 cancer-free men enrolled between 1996 and 2003. We followed up their mortality status via the National Death Registry through 2005. Four thousand men were randomly selected as the subcohort. Part III is a case-cohort study that tested whether high-sensitivity C-reactive protein (hsCRP), a marker of inflammation, increased risk of death from overall cancer including prostate cancer, using the same study population in part II.
Results. Part I: data on the interested association are limited and inconsistent. Part II and III: After a median 7.1 years of follow-up, 36 cases of prostate cancer death and 1,170 cases of overall cancer death were ascertained. Among the MetS components, only hyperglycemia was a significant risk factor for prostate cancer death; but the MetS alone was not. Compared to men without hyperglycemia, men with pre-diabetes, the MetS before onset of diabetes, and new-onset diabetes, had increased risk, but men with known diabetes at baseline had lower risk of prostate cancer death. High hsCRP at baseline was positively associated with risk of death from overall cancer (statistically significant) including prostate cancer (marginally significant), even with multivariate-adjustment.
Conclusions. The effects of each MetS components on risk of prostate cancer death were heterogeneous. Men in early stages of glycemia disorders had higher risk, while men in late stages of glycemia disorders had lower risk of prostate cancer death. Elevated hsCRP predicted increased risk of death from overall cancer, including prostate cancer. Measures that aim at reducing hyperglycemia and chronic inflammation deserve serious attention in cancer prevention programs.