The impact of Gleason pattern 4 ratio on recurrence following radical prostatectomy in Japanese patients with prostate cancer.

Abstract

114 Background: The 2014 International Society of Urological Pathology (ISUP) classified the Gleason grade into five groups and the Gleason score (GS) 7 was divided into groups 2 (GS3+4) and 3 (GS4+3). The ISUP recommended recording the Gleason pattern (GP) 4 ratio. However, no data are available on Japanese patients, and no studies have reported any difference between GS3+3 and a part of GS3+4. In this study, we evaluated the effect of the GP 4 ratio on recurrence following radical prostatectomy in Japanese patients with prostate cancer and revealed the equivalent between GS3+3 and part of GS3+4. Methods: We retrospectively evaluated 1,000 patients with prostate cancer who underwent radical prostatectomy at the author’s affiliated hospitals between 2005 and 2013. All prostatectomy specimen slides were reviewed by a single genitourinary pathologist according to ISUP 2014. Recurrence following radical prostatectomy was defined according to American Urological Association guidelines. The endpoint was defined as an increase in prostate-specific antigen (PSA) level. Results: Median patient age was 67 years (range, 42–77 years). Median serum PSA level was 6.8 ng/mL (range, 0.4–82 ng/mL). Median follow-up period was 59 months (range, 0.2–134 months). PSA progression was observed in 13.9% of pT2, 39.5% of pT3a, and 59.5% of pT3b. There were 164 group 1 cases (GS6), 484 group 2 (GS3+4), 212 group 3 (GS4+3), 39 group 4 (GS8), and 95 group 5 (GS9–10) cases. PSA progression-free survival was significantly different among the five groups (log rank; P = 0.0001). A significant difference was observed among the four groups with regard to the proportion by which the GP4 ratio increased (P = 0.0001) when groups 2 and 3 were divided by the GP4 ratio ( < 20%, 236 cases; 20–50%, 240 cases; 51–80%, 188 cases; and 81–100%, 17 cases). On the other hand, no difference was detected between GS3+3 and GS3+4 (GS4 < 20%) (P = 0.481). Conclusions: An increase in the GP4 ratio was correlated with PSA progression following radical prostatectomy in Japanese patients with prostate cancer. In addition, no difference was observed between GS3+3 and GS3+4 (GP4 < 20%), and GS3+4 (GP4 < 20%) patients may be an indication for active surveillance.