Improving the prediction of biochemical recurrence after radical prostatectomy with the addition of detailed pathology of the positive surgical margin and cribriform growth

Abstract

The risk on biochemical recurrence (BCR) after radical prostatectomy (RP) is usually estimated using PSA and pathological stage and grading including the presence of positive surgical margins (PSM). Objective was to investigate whether the presence of cribriform growth in the primary tumor, Grade Group (GG) at the PSM, and length of the PSM have added value in the prognostication. We analyzed data of 835 patients initially treated with RP between 2000 and 2017. Cox regression models were developed to compare the baseline model (PSA, pT-stage, pN-stage, GG at RP, and presence of PSM) with an extended model (adding the presence of cribriform growth, length and GG at the PSM) using the likelihood ratio test. Discrimination was assessed at internal validation by the time-dependent area under the receiver operating characteristic curve (AUC) at 3- and 5-year. A total of 224 men experienced BCR. Median follow-up for men without BCR was 50.4 months (interquartile range, IQR 11.9–95.5). The extended model had a significant better fit, χ2(4) = 31.0, p < 0.001 than the baseline model. The AUC of the 3- and 5-year extended model was 0.85 (95% CI 0.81–0.88) compared to 0.83 (95% CI 0.79–0.87) for the baseline model. Importantly, the presence of cribriform growth in the primary tumor, and GG ≥ 2 at PSM were associated with a higher risk on BCR. In conclusion, the addition of pathological variables improved the prediction of the risk on BCR after RP slightly. However, the clinical implications of this model are important.