External Validation of Briganti and Memorial Sloan-Kettering Cancer Centre Nomograms for Predicting Lymph Node Invasion in the Indian Cohort of Patients with Prostate Cancer

Briganti and Memorial Sloan-Kettering Cancer Centre (MSKCC) nomograms are the two commonly used models for predicting lymph node invasion (LNI) in patients with prostate cancer. However, they have never been validated in the Indian cohort of patients with prostate cancer. Hence, with this study, we aimed to externally validate Briganti (2012) and MSKCC nomograms in our dataset of patients who underwent robot-assisted radical prostatectomy (RARP). We reviewed our prospectively maintained RARP data to predict the probability of LNI using Briganti (2012) and MSKCC nomograms. The two models were validated by receiver operating characteristic (ROC) curve analysis, calibration plots, and decision curve analysis (DCA). Of the 482 patients included in this study, 127 (26.3%) had lymph nodal metastasis. ROC analysis revealed an area under the curve of 0.75 (0.70–0.80) and 0.76 (0.71–0.80) for the Briganti and MSKCC nomograms, respectively, in predicting LNI. Calibration plots for both Briganti and MSKCC nomograms showed under or overestimation at different predicted probabilities. DCA showed a net clinical benefit of both models at a threshold probability of 10%. Using 5% cut-off for threshold for lymph node dissection, Briganti nomogram would have sensitivity, specificity, PPV, and NPV of (126/127) 99.2%, (14/355) 3.9%, (126/467) 26.9%, and (14/15) 93.3%, respectively. Using the same cut-off, MSKCC nomogram would have sensitivity, specificity, PPV, and NPV of (126/127) 99.2%, (56/355) 15.7%, (126/425) 29%, and (56/57) 98%, respectively. With this study, we independently validated Briganti and MSKCC nomograms for predicting LNI in the Indian cohort of patients with prostate cancer.