The accuracy of ultrasensitive PSA in predicting disease progression after radical prostatectomy

Abstract

Objectives: To assess the role of ultrasensitive PSA values (usPSA) after radical prostatectomy in predicting the subsequent biochemical recurrence (BCR).

Material and methods: The study included 1836 patients who underwent open or robot-assisted RP at Turku University Hospital between 2003 and 2018. Exclusion criteria involved patients with adjuvant treatments and those who did not reach a PSA nadir <0.1 ng/ml, resulting in a final cohort of 1313 patients. The prognostic impact of the optimal usPSA nadir cut-off value 6 months after RP was investigated to predict subsequent BCR for the whole cohort (N = 1313). The optimal usPSA cut-off value was determined for patients at 3-5 years post-surgery (N = 806) and beyond 5 years (N = 493) of follow-up. We used the area under the curve (AUC) calculation and the Kaplan-Meier method.

Results: In a cohort with a median age of 64, primarily featuring Gleason score 7 prostate cancer. uPSA nadir of 0.01 ng/ml (AUC = 0.80) at the first monitoring post-surgery emerged as the optimal cut-off for identifying subjects at low (80%) or high (20%) risk of BCR within the first 3 years. Beyond this period, uPSA values during the first 3 [(AUC = 0.89; 3-5 years post-surgery) and (AUC = 0.81; beyond 5 years)] and 5 post-surgery years (AUC = 0.85) outperformed uPSA nadir in predicting subsequent BCR. Notably, EAU-defined high-risk patients with low uPSA nadir maintained substantial BCR-free survival.

Conclusion: In conclusion, a low usPSA predicts minimal BCR risk over the next 2-3 years post-measurement. Patients with low usPSA can benefit from reduced post-surgery PSA monitoring at 2- to 3-year intervals without compromising outcomes. This strategic approach optimizes resource allocation in busy urological outpatient clinics, especially valuable in publicly reimbursed healthcare systems like Finland.

Keywords: biochemical recurrence; prostate‐specific antigen; prostatic neoplasms; radical prostatectomy; ultrasensitive prostate‐specific antigen.

FIGURE 1

A study flowchart.

FIGURE 2

Biochemical progression free survival stratified by low usPSA levels and EAU prostate cancer risk groups. (A) Time point 1, that is, usPSA nadir. Under, usPSA nadir <0.010 ng/ml; over, usPSA nadir ≥0.010. (B) Time point 2, that is, usPSA level during first 3 years post‐surgery. Under, usPSA nadir <0.025 ng/ml; over, usPSA nadir ≥0.025. (C) Time point 3 i.e. usPSA level during first 5 years post‐surgery. Under, usPSA nadir <0.023 ng/ml; over, usPSA‐nadir ≥0.023. Prostate cancer risk group based on EAU guidelines: low risk, PSA ≤ 20, Gleason <8 or pathological T‐stage (pT) < 3; high risk, PSA > 20, Gleason ≥8 or pT ≥ 3. Lines: Red, high EAU risk and usPSA over cut‐off; green, high EAU risk and usPSA under cut‐off; blue, low EAU risk and usPSA under cut‐off; purple, low EAU risk and usPSA under cut‐off.