PSA density does not improve predictive accuracy of the UCSF-CAPRA score

Area of Science:

• Urology
• Oncology
• Medical Statistics

Background:

• The University of California, San Francisco Cancer of the Prostate Risk Assessment (CAPRA) score is a validated tool for predicting prostate cancer outcomes post-radical prostatectomy (RP).
• Prostate-specific antigen (PSA) density is an established prognostic variable, particularly in pre-diagnostic settings and for stratifying low-risk disease.

Purpose of the Study:

• To evaluate if replacing serum PSA with PSA density in the clinical CAPRA model enhances its predictive performance for prostate cancer outcomes after RP.
• To compare the predictive accuracy of the standard CAPRA score with an alternate CAPRA score incorporating PSA density.

Main Methods:

• A cohort of 2880 patients diagnosed with stage T1/T2 prostate cancer between 2000-2019 and treated with RP were analyzed.
• Two CAPRA scores were computed: standard (using serum PSA) and alternate (using PSA density).
• Recurrence-free survival was evaluated using life table and Kaplan-Meier analysis; Cox proportional hazards regression models assessed associations with recurrence risk.

Main Results:

• The alternate CAPRA model, using PSA density, showed shifts in risk scores for 16% of patients, with 7% increasing and 7% decreasing.
• Both standard and alternate CAPRA scores were associated with recurrence risk post-RP.
• Covariate fit statistics indicated a significantly better fit for the standard CAPRA model compared to the alternate model (p < 0.01).

Conclusions:

• The alternate CAPRA model using PSA density was associated with higher biochemical recurrence (BCR) risk but performed inferiorly to the standard CAPRA score in predicting BCR.
• Substituting PSA density for serum PSA does not improve the predictive accuracy of the CAPRA model for BCR across a range of prostate cancer risks.
• The standard CAPRA score remains the preferred tool for predicting BCR after RP in this cohort.