Prostate-Specific Antigen Doubling Time in Prediction of Prostate Cancer on Negative-Needle Biopsy

Abstract

Objective: To identify the role of prostatic specific antigen doubling time (PSADT) in predicting for cancer detection in patients with persistently elevated PSA after a previous negative biopsy.
Methods: From 2009 to 2011, 110 patients with the initial negative transrectal ultrasound guided prostate biopsy were followed with sequential PSA and repeated biopsy if indicated (persistently elevated PSA more than 4 ng/ml). The patient evaluation included age, prostate characteristics by digital rectal examination (DRE), total PSA (tPSA), percent free PSA (%fPSA), PSADT (month), PSA velocity (PSAV) (ng/ml/y), interval between first and second biopsy (month), prostate volume by ultrasound, number of core biopsy, and pathologic result of the second biopsy.
Result: Fourteen patients (12.7%) were diagnosed adenocarcinoma of prostate after the second biopsy. The mean age (66.1,66.1), tPSA (15.6,9.7), %freePSA (21.1,23.8) and prostate volume (47.1,56.9) in the group of positive biopsy were comparable with the negative biopsy group. The mean PSAV of the positive biopsy group was 1.8 ng/ml/yr versus 0.38 ng/ml/yr for the negative group (p<0.001) while the mean PSADT of the positive biopsy group was 6.4 months versus 27.8 months for the negative group (p<0.001). The prevalence of prostate cancer among PSADT groups (<5, 5-10, >10 month) was 4.5%, 8.2% and 0%, respectively. There was no positive biopsy in patients with PSADT more than 10 months.
Conclusion: The mean value of PSADT in the patients who needed to repeat biopsy differed significantly between men with and without prostate cancer, and this information can aid in the decision making for patients to avoid unnecessary repeat prostate biopsies.