A novel nomogram provides improved accuracy for predicting biochemical recurrence after radical prostatectomy

Abstract

Background: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 (BCRFS).Methods:A total of 337 patients who underwent RP between January 2010 and March 2017 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 BCRFS at 3 and 5 years after RP. Time-dependent receiver operating characteristic (ROC) curve and decision curve analyses were performed to identify the advantage of the new nomogram in comparison with the cancer of the prostate risk assessment post-surgical (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), considering these variables were significantly associated with BCR in both univariate and multivariate analyses (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 curve 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 BCRFS after RP.

Investigation of radiomics models for predicting biochemical recurrence of advanced prostate cancer on pretreatment MR ADC maps based on automatic image segmentation

“…Similarly, Riaz et al 22 concluded that tumor size of the dominant lesion measured on pretreatment MRI was associated with BCR in intermediate and high-risk PCa patients treated with RT, while Gleason score and the presence of extracapsular extension on MRI were the only significant predictors. Xia et al 8 retrospectively collected a total of 337 patients who underwent RP and considered that maximum diameter of the index lesion measured on pretreatment MRI was an independent predictor of BCR. Usually PCa is multifocal, so the measurement of tumor volume is complex and time-consuming and difficult to achieve in clinical practice.…”

“…BCR was defined as any PSA increase >2 ng/mL compared to the PSA nadir value for men who underwent RT with or without HT. For patients only received HT, BCR was define as castrate serum testosterone <1.7 nmol/L with either three consecutive increases in PSA at least one week apart resulting in two times exceeding the nadir by 50% and a PSA >2 ng/mL or radiological progression in appearance of new lesions 8 . The exclusion criteria were as followings: (a) Patients who received any treatment before their initial MRI examination.…”

“…For patients only received HT, BCR was define as castrate serum testosterone <1.7 nmol/L with either three consecutive increases in PSA at least one week apart resulting in two times exceeding the nadir by 50% and a PSA >2 ng/mL or radiological pro-gression in appearance of new lesions. 8 The exclusion criteria were as followings:…”

“…Its basis is to extract quantitative features (called radiomics features) from radiology images that cannot be observed by radiologists, and use these data to create a clinical decision support system 3 . Many studies were devoted to exploring the pretreatment MRI features to predict the recurrence of PCa and results were encouraging 4–8 . However, these research objects were mainly localized PCa treated with RP and/or RT.…”

“… 3 Many studies were devoted to exploring the pretreatment MRI features to predict the recurrence of PCa and results were encouraging. 4 , 5 , 6 , 7 , 8 However, these research objects were mainly localized PCa treated with RP and/or RT. In actual clinical work, many cancers are diagnosed in advanced stages.…”