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.
Gurbuz C, Canat L, Atis G, Guner B, Caskurlu T. Are you the author?
Department of 2nd Urology, Istanbul Goztepe Training and Research Hospital, Istanbul, Turkey.
Reference: Kaohsiung J Med Sci. 2012 Dec;28(12):649-53.