Consistency of prostate biopsy and radical prostatectomy Gleason grade groups and nomograms establishment for predicting upgrading and downgrading

Abstract

Objective To evaluate the consistency between prostate biopsy and postoperative pathological grade, analyze the influencing factors that may lead to upgrade or downgrade, and to establish a prediction model. Methods The clinical data of biopsy GS3+ 3=6(GR1, 330 cases) and GS3+ 4=7(GR2, 340 cases) patients from January 2013 to December 2018 in the first affiliated hospital, College of Medicine of Zhejiang university were retrospectively analyzed. The median age was 67 years old(ranging 35 to 100 years old). The median BMI was 23.74 kg/m2(ranging 16.22-38.74 kg/m2). The Median tPSA was 10.266 ng/ml(ranging 0.017-147.575 ng/ml). The median prostate volume was 29.43 ml(5.92-187.20 ml). The median PSAD was 0.34 (ranging 0.01-4.02). The median percentage of positive puncture cores was 0.25 (ranging 0.08-1.00). There were 161 patients in clinical stage ≤T1c, 344 patients in T2a-T2c and 165 patients in clinical stage ≥T3. 670 cases all accepted the radical prostatectomy. Consistency of prostate biopsy and radical prostatectomy Gleason grade was recorded. If the postoperative Gleason grade was higher than that in biopsy, it was defined as upgrade. Otherwise, it was defined as downgrade. Multivariate logistic regression model was used to evaluate the influencing factors leading to upgrades in GR1 patients or downgrades in GR2 patients. Nomograms were drawn based on the models with AUC and Horsmer-Lemeshaw test conducted to test the discrimination and calibration of the models. Results Among the 670 patients included, 165 cases (50.0% of GR1) upgrades and 27 cases (7.9% of GR2) downgrades. PSAD≥0.25(OR=3.015) and clinical stage≥T2b(OR=7.185)were independent influencing factors for the upgrade in GR1 patients, while PSAD<0.15(OR=4.208) and clinical stage≤T1c(OR=4.530) were independent influencing factors for downgrade. The nomograms were drawn with the above variables. The AUC of the model (0.781 for GR1 group, 0.741 for GR2 group) and the hosmer-remeshaw test results (P=0.993 for GR1 group, P=0.234 for GR2 group) show that the nomograms have good discrimination and calibration. Conclusions PSAD and clinical stage are independent influencing factors for the upgrade or downgrade. Nomograms may provide help for clinicians to judge the accuracy of prostate biopsy. However, the nomograms still needs to be verified in clinical practice Key words: Prostate neoplasms; Gleason score; Prostate biopsy; Radical prostatectomy