External Validation of the Martini-Klinik Nomogram Predicting the Indication for Adjuvant Radiation Therapy According...

To externally validate the Martini-Klinik nomogram based on patient and clinical tumor characteristics predicting the indication for adjuvant radiation therapy after radical prostatectomy according to guideline recommendations of the European Association of Urology (EAU) in high-risk prostate cancer patients treated with radical prostatectomy.

Relying on a tertiary-care database, we identified high-risk prostate cancer patients treated with radical prostatectomy (01/2014-12/2024). External validation was assessed in terms of accuracy, calibration and net benefit, using decision curve analyses.

Of 404 high-risk prostate cancer patients, 182 (45%) had the indication for adjuvant radiation therapy according to current EAU guidelines. The nomogram predicted the outcome with 79% accuracy. A high level of agreement between the predicted and observed probability of indication for adjuvant radiation therapy was observed. Minimal overestimation from the ideal predictions were noted for predicted probabilities between 25% and 50%, as well as a minimal underestimation between the predicted probability of 0% and 20% as well as 75% and 100%. In decision curve analyses, the use of the nomogram resulted in greater net benefit for all threshold probabilities between 25% and 95%, relative to both competing strategies - none or all treated.

This external validation within a contemporary tertiary-care cohort confirmed the ability of the Martini-Klinik nomogram to predict the indication for adjuvant radiation therapy after radical prostatectomy according to current EAU guideline recommendations in high-risk prostate cancer patients. The present nomogram may support clinicians in preoperative patient counseling about the risk for adjuvant treatment.