External evaluation of the Briganti nomogram to predict lymph node metastases in intermediate-risk prostate cancer patients

Purpose The Briganti nomogram can be used with a threshold of 5% to decide when to offer lymph node dissection during radical prostatectomy. The objective of the study was to assess the accuracy of the Briganti nomogram on intermediate-risk prostate cancer patients managed in a single academic department. Methods We retrospectively reviewed the files of all patients managed by radical prostatectomy (RP) and bilateral pelvic lymph node dissection (BPLND) in our center between 2005 and 2017. The overall accuracy of the model in predicting metastatic lymph node disease was quantified by the construction of a receiver-operator characteristic (ROC) curve. A calibration plot was drawn to represent the relationship between the predicted and observed frequencies. Results We included 285 patients, among whom 175 (61.4%) were classified as intermediate risk as defined by D’Amico. The median follow-up was 60 (34–93) months. Twenty-seven patients (9.5%) were diagnosed with lymph node metastases. The median number of lymph nodes removed was 10 (7–14). The mean Briganti score was 19.3% in patients with lymph node involvement (LNI) and 6.3% in patients without LNI. Focusing on intermediate-risk patients, 91(52%) and 84 (48%) had a Briganti score