title: Is a decreased serum testosterone level a risk factor for prostate cancer? A cohort study of korean men.
abstract: OBJECTIVE
  To investigate patients who had transrectal ultrasonography (TRUS)-guided prostate biopsy to define the role of the serum testosterone level in predicting prostate cancer risk and its association with a high Gleason score.
  
  
  METHODS
  A total of 568 patients who underwent prostate biopsy were entered in this study. We divided the patients into two groups according to serum testosterone level (median level, 3.85 ng/ml): the high-testosterone group (n=285) and the low-testosterone group (n=283). Multivariate regression analysis was used to define the effect of age, prostate volume, serum prostate-specific antigen (PSA) level and PSA density, and serum testosterone level on the risk of prostate cancer and a high Gleason score.
  
  
  RESULTS
  Baseline characteristics did not differ significantly between the two groups. Compared with the high-testosterone group, the low-testosterone group had a significantly higher prostate cancer incidence (38.9% vs. 29.5%, p=0.018). Factors associated with an increased risk of prostate cancer were increased age (odds ratio [OR]=1.08, 95% confidence interval [CI]=1.25-3.16, p=0.001), a high serum PSA level (OR=3.35, 95% CI=2.63-4.25, p=0.001), a low prostate volume (OR=0.183, 95% CI=0.11-0.30, p=0.001), and a low serum testosterone level (OR=1.99, 95% CI=1.25-3.16, p=0.001). Among these, only the serum PSA level was a strong predictor of high-grade prostate cancer (Gleason score ≥7) (OR=2.19, 95% CI=1.57-2.95, p=0.001).
  
  
  CONCLUSIONS
  Patients with lower levels of serum testosterone had a higher risk of prostate cancer than did patients with high serum testosterone. Even though a lower serum testosterone level was a predictor of prostate cancer risk, it was not associated with an increased risk of high-grade prostate cancer.
authors.affiliation: Department of Urology, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Bo Sung
authors.initials: BS
authors.lastname: Shin
authors.forename: Eu Chang
authors.initials: EC
authors.lastname: Hwang
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Im
authors.forename: Sun-Ouck
authors.initials: SO
authors.lastname: Kim
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Jung
authors.forename: Taek Won
authors.initials: TW
authors.lastname: Kang
authors.forename: Dong Deuk
authors.initials: DD
authors.lastname: Kwon
authors.forename: Kwangsung
authors.initials: K
authors.lastname: Park
authors.forename: Soo Bang
authors.initials: SB
authors.lastname: Ryu