ULTRASENSITIVE DETECTION OF PROSTATE SPECIFIC ANTIGEN IN THE FOLLOWUP OF 422 PATIENTS AFTER RADICAL PROSTATECTOMY:

Usefulness of ultrasensitive prostate-specific antigen assay for early detection of biochemical failure after radical prostatectomy

BACKGROUND

In order to assess whether the prostate-specific antigen (PSA) nadir obtained with an ultrasensitive PSA assay can be used as a prognostic indicator for patients undergoing radical prostatectomy, we investigated it retrospectively.

METHODS

Between October 1997 and July 2003, 46 patients underwent radical prostatectomy for prostate cancer at our institution. None of them received preoperative treatment. Levels of PSA were measured with an ultrasensitive PSA assay every 1-3 months after prostatectomy. Biochemical recurrence was defined as a PSA level of 0.2 ng/mL or higher.

RESULTS

There was a significant difference in PSA nadir between the biochemical recurrence group and the no recurrence group (P < 0.001). The receiver operating characteristics (ROC) curve gave an optimal cut-off value for PSA nadir of 0.01 ng/mL, demonstrating a significant difference in biochemical recurrence after radical prostatectomy. No patient with a PSA nadir level <0.01 ng/mL showed biochemical failure, while 15 out of 22 patients with PSA nadir levels >or=0.01 ng/mL showed biochemical failure.

CONCLUSION

The PSA nadir level obtained using an ultrasensitive PSA assay is an excellent predictor of biochemical recurrence after radical prostatectomy. Early detection of recurrence offers the possibility of early salvage therapy.

Relapse and cure rates of prostate cancer patients after radical prostatectomy and 5 years of follow-up

OBJECTIVES

We have compared the ability of an ultrasensitive prostate specific antigen assay and a regular PSA assay to identify relapse and cure rates of prostate cancer patients after radical prostatectomy, during a 5-year follow-up period.

DESIGN AND METHODS

We measured PSA by an ultrasensitive assay (detection limit 0.001 ng/mL) and a conventional PSA assay (detection limit 0.1 ng/mL) in serial serum samples obtained from 197 patients who have undergone radical prostatectomy.

RESULTS

Based on ultrasensitive PSA analysis, we have identified three groups of patients: 62% of patients did not show any significant changes in serum PSA; 15% of patients demonstrated slow PSA increases over time but none of the measurements exceeded 0.1 ng/mL within 4 years; and 23% of the patients had relatively significant increases of serum PSA and were classified as having 'fast relapse'. The vast majority of these patients were subsequently identified to have relapse by the regular PSA assay. The ultrasensitive PSA assay detected relapse by an average of eighteen months earlier than the conventional PSA method. Fast relapsing patients were associated with other prognostic indicators of the disease including pre-operative PSA, tumor volume, Gleason score, clinical stage, surgical margin positivity, periprostatic tissue involvement, capsular invasion and seminal vesicle invasion. The group with slowly rising PSA had prognosis which was between the patients in remission and fast relapsing patients.

CONCLUSIONS

The use of ultrasensitive PSA analysis for monitoring patients after radical prostatectomy provides earlier detection of relapse (by 18 months) and identifies three distinct groups of patients. Fast relapsing patients should be good candidates for early therapeutic interventions.