Poorly differentiated prostate cancer treated with radical prostatectomy: Long-term outcome and incidence of pathological downgrading

Purpose: Patients with high grade (Gleason score 8 to 10) prostate cancer on biopsy are at high risk for cancer recurrence after local treatment, such as radiation therapy and radical prostatectomy. We examined long-term outcomes in patients with high grade prostate cancer on biopsy who were treated with radical prostatectomy alone. We also investigated the impact on outcomes of changes in the radical prostatectomy Gleason score. Materials and Methods: Of 5,662 patients who underwent radical prostatectomy during 20 years 238 had a biopsy Gleason score of 8 to 10. We analyzed the rate of biochemical recurrence in this subgroup according to the Gleason grade of cancer in the radical prostatectomy specimen. Results: Ten-year biochemical recurrence-free probability in the cohort was 39%. However, 45% of patients (95% CI 38 to 51%) with Gleason score 8 to 10 cancer on biopsy had a Gleason score of 7 or less in the radical prostatectomy specimen. These patients had a 10-year biochemical recurrence-free probability of 56% compared to 27% in those with a final Gleason score that remained 8 to 10 (p = 0.0004). On multivariate analysis neither prostate specific antigen nor biopsy features, including total number of cores, number of cores with cancer and percent of cancer in the cores, was a significant predictor of downgrading. However, clinical stage and biopsy Gleason score were significant with 58% of cT1c and 51% of biopsy Gleason score 8 cancers downgraded. Almost 65% of cT1c Gleason score 8 cancers were downgraded compared to 11% of cT3 Gleason score 9 cancers. Conclusions: Patients diagnosed with poorly differentiated prostate cancer (Gleason score 8 to 10) on biopsy do not uniformly have a poor prognosis. Of the patients 39% remain free of cancer recurrence 10 years after radical prostatectomy. Of these cancers 45% have a lower Gleason score in the radical prostatectomy specimen and a correspondingly more favorable long-term outcome. Predictors of downgrading are lower clinical stage (cT1c) and Gleason score 8 in the biopsy specimen.