External validation of a nomogram for identification of pathologically favorable disease in intermediate risk...

To establish an external validation of the new nomogram from Gandaglia et al which provides estimates of the probability of pathological favorable disease in pre-operatively defined intermediate-risk PCa.

Overall, 2928 intermediate-risk PCa patients according to the D'Amico classification undergoing RP and bilateral lymph node dissection in seven academic centres between 2000 and 2011. Pathologically favorable PCa was defined as low-grade organ-confined disease. The Receiver Operating Characteristic (ROC) curve was obtained to quantify the overall accuracy (Area Under the Curve, AUC) of the model to predict specimen-confined (SC) disease. Calibration curve was then constructed to illustrate the relationship between the risk-estimates obtained by the model and the observed proportion of SC disease. Kaplan-Meier method was used for PSA recurrence-free survival (PSA-RFS) assessment.

Median age was 68 years. 10.6% patients finally presented pathologically favorable disease characteristics at RP. A higher PSAD (OR = 0.01; 95%CI = 0.00-0.04; P < 0.0001) and percentage of positive cores (OR = 0.97; 95%CI = 0.96-0.98; P < 0.0001) were associated with a reduced probability of favorable disease at RP in multivariate analysis. ROC curve analysis showed strongest accuracy of the model (AUC = 0.82; 95%CI = 0.79-0.84). Favorable PCa had a significantly better PSA recurrence-free survival rates as compared to unfavorable PCa after RP (94.2% vs 74.4% at 4 years, P < 0.0001).

This external validation of the Gandaglia nomogram shows relevant accuracy with one out of ten patients in this intermediate risk PCa group with pathologically proven organ-confined disease. This validated risk calculator can help physician to distinguish favorable intermediate risk PCa that can be treated by conservative approach or safer nerve-sparing surgery.