MP57-05: One novel nomogram to predict biochemical recurrence more accurate in radical prostatectomy

Jian Lu*, Ji De He, Ye Yan, Xue Hua Zhu, Ze Nan Liu, Hai Zhui Xia, Hai Bi, Bin Yang, Run Zhuo Ma, Wei He, Zhi Ying Zhang, Yu Ting Zhang, Lu Lin Ma, Xiao Fei Hou, Beijing, China, People's Republic of

Introduction: Various prediction tools have been developed to predict biochemical recurrence (BCR) after radical prostatectomy (RP), however, few of the previous prediction tools used serum prostate specific antigen (PSA) nadir after RP and maximum tumor diameter (MTD) at the same time. In this study, a nomogram incorporating MTD and PSA nadir was developed to predict BCR-free survival.

Methods: 337 patients who underwent RP were retrospectively enrolled in this study. The maximum diameter of the index lesion was measured on magnetic resonance imaging (MRI). Cox regression analysis was performed to evaluate independent predictors of BCR. A nomogram was subsequently developed for the prediction of BCR-free survival at 3 and 5 years after RP. Time-dependent receiver operating characteristic (ROC) curve and decision curve analysis were performed to identify the advantage of the new nomogram in comparison with the CAPRA-S score.

Results: A novel nomogram was developed to predict BCR by including PSA nadir, MTD, Gleason score, surgical margin (SM), and seminal vesicle invasion (SVI), since these variables were significantly associated with BCR in both univariate and multivariate analysis (p <0.05). In addition, a basic model including Gleason score, SM, and SVI was developed and used as a control to assess the incremental predictive power of the new model. The concordance index of our model was slightly higher than CAPRA-S model (0.76 vs. 0.70, p =0.02) and it was significantly higher than that of the basic model (0.76 vs. 0.66, p =0.001). Time-dependent ROC curves and decision curve analyses also demonstrated the advantages of the new nomogram.

Conclusions: PSA nadir after RP and MTD based on MRI before surgery are independent predictors of BCR. By incorporating PSA nadir and MTD into the conventional predictive model, our newly developed nomogram significantly improved the accuracy in predicting BCR-free survival after RP.

Source of Funding: This work was supported by grants from the National Natural Science Foundation of

China (No.61871004); National key research and development program of China (No.

2018YFC0115900) and Peking University Medicine Fund of Fostering Young Scholars’

Scientific & Technological Innovation and the Fundamental Research Funds for the

Central Universities (No. BMU2020PYB002). Funds were used for the collection and

analysis of data.