Abstract
OBJECTIVE: • To investigate the predictive ability of nomograms at the extremes of preoperative clinical parameters by examining the predictive ability across all prostate cancer risk groups. PATIENTS AND METHODS: • The Columbia University Urologic Oncology Database was reviewed: 3663 patients underwent radical prostatectomy from 1988 to 2008. Patients who had received neoadjuvant or adjuvant therapy, or had insufficient clinical parameters for estimation of 5-year progression-free probability using the preoperative Kattan nomogram were excluded. • A total of 1877 patients were included and stratified by D'Amico risk criteria. Mean estimated nomogram progression rates were compared with actuarial Kaplan-Meier survival statistics. • A regression model to predict progression-free survival was fitted with estimated nomogram score and concordance indices were calculated for the entire model and subsequently for each risk group. RESULTS: • Of 1877 patients, 857 (45.6%) were low risk, 704 (37.5%) were intermediate risk, and 316 (16.8%) were high risk by D'Amico criteria. • Mean estimated nomogram survival and actuarial Kaplan-Meier survival at 5 years were 90.5% and 92.2% (95% CI 89.2-94.3) for low-risk, 76.7% and 77.8% (73.3-81.7) for intermediate-risk, and 65.8% and 60.4% (52.0-67.7) for high-risk groups, respectively. Using nomogram score in the regression model, the c-index for the full model was 0.61. • For low-, intermediate- and high-risk patients independently the c-index was 0.60, 0.59 and 0.57, respectively. When low-, intermediate- and high-risk patients were independently removed from the model the c-index was 0.64, 0.65 and 0.55, respectively. • The c-index for the full model using the categorical nomogram risk scores was 0.67. Similar to the D'Amico model, the c-index improved to 0.69 when intermediate-risk patients were removed from the model. CONCLUSIONS: • The study confirms the ability of preoperative nomograms to accurately predict actuarial survival across all risk groups. • The predictive ability of the nomogram varies by risk group, yet even at the extremes of high-risk and low-risk prostate cancer the nomogram accurately predicts outcome.