Postoperative Nomogram for Disease Recurrence After Radical Prostatectomy for Prostate Cancer

TLDR

Existing models group prostate cancer patients by recurrence risk, but none combine postoperative pathologic factors, and preoperative stage and Gleason grade only approximate postoperative findings, so incorporating postoperative data should improve prognostic accuracy. The study aimed to develop a postoperative nomogram to more accurately predict disease recurrence risk after radical prostatectomy compared to a prior preoperative model. Using Cox proportional hazards regression on 996 men, the nomogram incorporated pretreatment PSA, specimen Gleason sum, capsular invasion, margin status, seminal vesicle invasion, and lymph node status, with treatment failure defined by clinical recurrence, rising PSA, or adjuvant therapy, and was validated internally and on an external cohort. The nomogram predicted a 7‑year recurrence‑free probability of 73% (95% CI 68–76%) and achieved an AUC of 0.89, indicating accurate discrimination.

Abstract

Although models exist that place patients into discrete groups at various risks for disease recurrence after surgery for prostate cancer, we know of no published work that combines pathologic factors to predict an individual's probability of disease recurrence. Because clinical stage and biopsy Gleason grade only approximate pathologic stage and Gleason grade in the prostatectomy specimen, prediction of prognosis should be more accurate when postoperative information is added to preoperative variables. Therefore, we developed a postoperative nomogram that allows more accurate prediction of probability for disease recurrence for patients who have received radical prostatectomy as treatment for prostate cancer, compared with the preoperative nomogram we previously published.By Cox proportional hazards regression analysis, we modeled the clinical and pathologic data and disease follow-up for 996 men with clinical stage T1a-T3c NXM0 prostate cancer who were treated with radical prostatectomy by a single surgeon at our institution. Prognostic variables included pretreatment serum prostate-specific antigen level, specimen Gleason sum, prostatic capsular invasion, surgical margin status, seminal vesicle invasion, and lymph node status. Treatment failure was recorded when there was either clinical evidence of disease recurrence, a rising serum prostate-specific antigen level (two measurements of 0.4 ng/mL or greater and rising), or initiation of adjuvant therapy. Validation was performed on this set of men and a separate sample of 322 men from five other surgeons' practices from our institution.Cancer recurrence was noted in 189 of the 996 men, and the recurrence-free group had a median follow-up period of 37 months (range, 1 to 168 months). The 7-year recurrence-free probability for the cohort was 73% (95% confidence interval, 68% to 76%). The predictions from the nomogram appeared to be accurate and discriminating, with a validation sample area under the receiver operating characteristic curve (ie, a comparison of the predicted probability with the actual outcome) of 0.89.A postoperative nomogram has been developed that can be used to predict the 7-year probability of disease recurrence among men treated with radical prostatectomy.