When should we expect no residual tumor (pT0) once we submit incidental T1a-b prostate cancers to radical prostatectomy?

Objectives: To date, no tool exists to predict pT0 at radical prostatectomy (RP) in patients with T1a-T1b prostate cancer (PCa) after surgery for benign prostatic hyperplasia (SxBPH). We aimed to fill this gap by developing a user-friendly flowchart to assist urologists when incidental PCa is diagnosed and a clinical decision is required. Methods: We analyzed 158 T1a-T1b prostate cancers patients who underwent RP between 1996 and 2009. A risk stratification tool was developed applying the tree modeling technique of classification and regression tree analysis (CART) and relying on all the available pre-RP characteristics (age, prostate-specific antigen [PSA] before SxBPH, PSA after SxBPH, cT1a-T1b stage, prostate volume and Gleason sum at SxBPH). Then, the accuracy of the proposed model using 200 bootstrap resamples for internal validation was calculated. Results: A total of 95 patients (60.1%) were stage T1a, and 63 (39.9%) were stage T1b. The median values of PSA before and after SxBPH were 4.2 and 1.1ng/mL, respectively. A total of 22 patients (13.9%) showed no residual tumor (pT0) at RP. The CART analyses identified three groups at risk of having residual disease at RP: (i) PSA after SxBPH>1.0ng/mL (pT0 prevalence: 3.8%); (ii) PSA after SxBPH2.0ng/mL (pT0 prevalence: 14.8%); and (iii) PSA after SxBPH