The predictive factor for pathological downgrading after prostatectomy in patients with biopsy Gleason score 4+3 or 4+4 prostate cancer

The proportion of Gleason pattern (GP) 4 prostate cancers at prostate biopsy has a clinically significant impact on risk stratification for patients with prostate cancer. In pathological diagnosis including GP 4, a biopsy Gleason score (GS) of 3+4 has a more favorable prognosis than a GS of 4+3 and 4+4. However, the discrepancy between biopsy and prostatectomy specimens is well known. The current study investigated the clinical parameters and biopsy specimens associated with pathological downgrading after prostatectomy in biopsies with a GS of 4+3 or 4+4 prostate cancer. A total of 302 patients with prostate cancer who underwent robot-assisted radical prostatectomy between August 2013 and May 2019 were retrospectively reviewed. A total of 103 patients had biopsies with GSs of 4+3 and GS 4+4 (unfavorable pathology). The proportion of patients who were downgraded from unfavorable disease to GS ≤3+4 (favorable pathology) in prostatectomy specimens was investigated. Logistic regression analysis was used to explore the association between clinical parameters and downgrading in prostatectomy specimens. A total of 43 patients (41.7%) were downgraded from biopsy GS to prostatectomy GS. The proportions of downgrade in biopsy GS 4+4 and 4+3 were 14.6 and 27.1%, respectively. The percentage of highest GS out of positive biopsy cores and the maximum percentage of cancer involvement within a positive core with the highest GS were lower in the downgrade group than in the no downgrade group (45 vs. 66.7%, P=0.025; 20 vs. 30%, P=0.048, respectively). When performing multivariate logistic regression analysis, the only significant predictor for downgrade was lower percentage of highest GS cores out of positive biopsy cores (odds ratio, 2.469; 95% confidence interval, 1.029-5.925 P=0.043). In conclusion, patients with biopsy GS 4+4 and 4+3 often exhibit a downgrade to GS 3+4 or less in prostatectomy specimens. The lower percentage of highest GS cores out of positive biopsy cores was associated with downgrade.