Added value of PHI in predicting lymph node invasion in prostate cancer: an external validation

To determine the predictive performance of the Briganti 2017 and MSKCC nomograms with the addition of Prostate Health Index (PHI) in a Chinese cohort of prostate cancer patients undergoing robot-assisted radical prostatectomy and extended pelvic lymph node dissection.

This single-center retrospective study included 473 prostate cancer patients who underwent robot-assisted radical prostatectomy with extended pelvic lymph node dissection from Dec. 2021 to Dec. 2025. The two nomograms were validated, and PHI was incorporated as a continuous variable. Model performance was assessed using AUC, calibration plots, and decision curve analysis, with the DeLong test for AUC comparison. This study was registered in the Medical Research Registration and Filing Information System of the National Health Security Information Platform of China (Registration No.: MR-50-25-036796, retrospectively registered).

Lymph node invasion (pN1) was confirmed in 26.0% (123/473) of the cohort. The original Briganti 2017 and MSKCC nomograms had AUCs of 0.69 (95% CI: 0.61-0.79) and 0.71 (95% CI: 0.62-0.78) with satisfactory calibration. PHI incorporation significantly improved discrimination, raising their AUCs to 0.787 (absolute improvement 0.093, P < 0.01) and 0.782 (absolute improvement 0.077, P < 0.01), respectively. Decision curve analysis showed PHI expanded the threshold probability range of positive net benefit from 10% to 30% to 10%-40% for both models.

The Briganti 2017 and MSKCC nomograms showed acceptable predictive performance for lymph node invasion in Chinese prostate cancer patients. PHI enhances their discriminatory ability and clinical utility, supporting its use as a valuable preoperative biomarker for pN1 in prostate cancer.