A PROSPECTIVE STUDY TO EVALUATE THE ROLE OF COMPLEXED PROSTATE SPECIFIC ANTIGEN AND FREE/TOTAL PROSTATE SPECIFIC ANTIGEN RATIO FOR THE DIAGNOSIS OF PROSTATE CANCER:

Complexed prostate-specific antigen for the diagnosis of biochemical recurrence after radical prostatectomy

OBJECTIVES

To determine the validity of using complexed prostate-specific antigen (cPSA) levels for diagnosing biochemical recurrence after radical prostatectomy (RP).

PATIENTS AND METHODS

With linear regression modelling, we determined threshold cPSA levels for biochemical recurrence in patients after RP for clinically localized prostate cancer. We calculated sensitivity, specificity, predictive values, and likelihood ratio tests of each threshold for diagnosing biochemical recurrence using total PSA (tPSA) as the reference standard.

RESULTS

In the regression models, tPSA and cPSA were highly correlated (r = 0.99). For the diagnosis of biochemical recurrence, tPSA thresholds of 0.20 and 0.40 ng/mL corresponded to cPSA thresholds of 0.12 ng/mL (95% confidence interval 0.08-0.17) and 0.29 (0.22-0.28) ng/mL, respectively. For the detection of biochemical recurrence, a cPSA threshold of 0.12 ng/mL had a sensitivity of 96%, specificity of 88%, positive predictive value of 89%, negative predictive value of 88%, positive likelihood ratio of 8, and negative likelihood ratio of 0.05; the respective values for a cPSA threshold of 0.29 ng/mL were 96%, 96%, 96%, 96%, 24 and 0.04.

CONCLUSIONS

cPSA has high validity for the diagnosis of biochemical recurrence after RP. Pending external validation, cPSA might be useful for biochemical surveillance after RP.

Prostate-specific antigen (PSA) complexed to alpha1-antichymotrypsin improves prostate cancer detection using total PSA in Japanese patients with total PSA levels of 2.0-4.0 ng/mL

OBJECTIVE

To assess the utility of prostate-specific antigen (PSA) complexed to alpha1-antichymotrypsin (PSA-ACT) in prostate cancer screening in Japanese men with a total PSA level of 2.0-4.0 ng/mL, as improving cancer detection in men with these total PSA levels is a challenge for clinical urologists.

PATIENTS AND METHODS

Total PSA and PSA-ACT were prospectively assessed and prostate biopsy recommended for patients who met either of two thresholds, i.e. a total PSA of > or = 2.0 ng/mL or a PSA-ACT of > or= 1.5 ng/mL. The diagnostic ability of total PSA and PSA-ACT, and free-to-total PSA ratio and prostate volume-adjusted density were evaluated by receiver operating characteristic (ROC) analysis.

RESULTS

Of 1003 men enrolled, 547 met the biopsy criteria and a biopsy was taken in 315 (57.6%) patients. The area under the ROC curve for PSA-ACT (0.679) was significantly greater than that for total PSA (0.601, P = 0.04) and equivalent to that for the free-to-total ratio (0.686, P = 0.911) in 116 men, including 27 with cancer with total PSA levels of 2.0-4.0 ng/mL. PSA-ACT was more specific than the free-to-total ratio at a sensitivity of 95% (36% vs 18%, P < 0.05). The best variable for discriminating between cancer and benign disease in men with PSA levels of 2.0-4.0 ng/mL was PSA-ACT density (area under the curve 0.852) which provided 66% specificity at a sensitivity of 90%.

CONCLUSIONS

PSA-ACT is better than total PSA and equivalent to the free-to-total ratio for detecting prostate cancer in men with PSA levels of 2.0-4.0 ng/mL, and is thus useful for reducing the number of unnecessary biopsies.