The Shared Equal Access Regional Cancer Hospital (SEARCH) nomogram for risk stratification in intermediate risk group of men with prostate cancer: validation in the Duke Prostate Center database

OBJECTIVES To validate the Shared Equal Access Regional Cancer Hospital (SEARCH) nomogram to better risk stratify men with intermediate-risk pathology after prostatectomy (positive surgical margins, PSM, and/or extracapsular disease, ECE, without seminal vesicle or lymph node involvement) in a tertiary referral centre (the Duke Prostate Center, DPC). PATIENTS AND METHODS We retrospectively analysed 485 men in the DPC cohort with PSM and/or ECE but without seminal vesicle or lymph node involvement. The predicted risk of biochemical progression-free probability at 1, 3 and 5 years was estimated by the SEARCH and updated Kattan postoperative nomograms. Calibration plots were generated and accuracy assessed with the concordance index. RESULTS The SEARCH nomogram appeared to be well calibrated, with the highest-risk quartile having a predicted < 60% progression-free probability at 5 years, vs > 80% for the lowest risk. In comparison, overall external calibration appeared to be similar for the updated Kattan nomogram, although there was less separation between the highest- and lowest-risk quartiles. The SEARCH model had an overall predictive accuracy of 0.65, which compared favourably with the updated Kattan nomogram (0.57). CONCLUSION In an external dataset, the SEARCH nomogram to predict progression-free probability for men at intermediate risk after prostatectomy was well calibrated and performed better than the updated postoperative Kattan nomogram.