title: The role of serum testosterone to prostate-specific antigen ratio as a predictor of prostate cancer risk.
abstract: We analyzed the ratio of serum total testosterone (sTT) to prostate-specific antigen (PSA) as a predictor of prostate cancer risk. One-hundred-four consecutive men with a normal digital rectal examination and a serum PSA level of 2.5-10 ng/ml underwent transrectal ultrasonography-guided biopsy using a 10-core scheme. The sTT level was determined before the procedure using a chemiluminescent assay, and the ratio of sTT to PSA (sTT/PSA) was calculated after transforming sTT measurements from ng/dL to ng/mL. The overall cancer detection rate was 17.3%. The median sTT level was 332 ng/dl in men with cancer and 413 ng/dL in those without (p = 0.032). The median sTT/PSA ratio in these groups was 0.55 and 0.74, respectively (p = 0.035). The receiver operator characteristic (ROC) method was used to evaluate the properties of the sTT/PSA ratio, with testosterone and PSA as predictors of prostate cancer risk. The accuracy of the sTT/PSA ratio in prostate cancer diagnosis, represented by the area under the curve (AUC), was 0.739 (95% CI 0.640-0.823, p < 0.05). Optimizing the sensitivity and specificity of the sTT/PSA ratio using the ROC provided a cutoff point of 0.60, which corresponded to 82% sensitivity and 62% specificity. When the patients were divided into normal- and low-sTT level groups according to testosterone value (300 ng/dl), the probability of detecting prostate cancer was 3.3-fold higher in hypogonadal men as compared with eugonadal men. These results support the use of the sTT-to-PSA ratio for predicting the risk of prostate cancer and increasing the specificity of PSA measurement.
authors.affiliation: Department of 2nd Urology, Istanbul Goztepe Training and Research Hospital, Istanbul, Turkey. gurbuzcenk@yahoo.com
authors.forename: Cenk
authors.initials: C
authors.lastname: Gurbuz
authors.forename: Lutfi
authors.initials: L
authors.lastname: Canat
authors.forename: Gokhan
authors.initials: G
authors.lastname: Atis
authors.forename: Bayram
authors.initials: B
authors.lastname: Guner
authors.forename: Turhan
authors.initials: T
authors.lastname: Caskurlu
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001706:Biopsy; D055088:Early Detection of Cancer / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000032:analysis*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis; D012372:ROC Curve; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D017430:Prostate-Specific Antigen