Presence of biopsy Gleason pattern 5 + 3 is associated with higher mortality after radical prostatectomy but not after external beam radiotherapy compared to other Gleason Grade Group IV patterns+

Background: We hypothesized that Gleason Grade Group (GGG) IV patients treated with radical prostatectomy (RP) or external beam radiotherapy (EBRT) exhibit different cancer-specific mortality (CSM) rates according to underlying Gleason patterns (GP): 4 + 4 versus 3 + 5 versus 5 + 3. Materials and Methods: We identified all GGG IV patients treated with either RP or EBRT within the Surveillance, Epidemiology, and End Results 2004–2016 database. The effect of biopsy GP on CSM (3 + 5 vs. 4 + 4 vs. 5 + 3) was tested in Kaplan–Meier and multivariable competing risks regression models (adjusted for PSA, age at diagnosis, cT-, and cN-stage). Results: Of 26,458 GGG IV patients, 14,203 (53.7%) were treated with EBRT and 12,255 (46.3%) with RP. Of RP patients, 15.3 versus 81.2 versus 3.4% exhibited biopsy GP 3 + 5 versus 4 + 4 versus 5 + 3 and respective 10-year CSM rates were 6.5 versus 6.2 versus 12.6% (p <.001). In multivariable analyses addressing RP patients, GP 5 + 3 was associated with two-fold higher CSM rate than GP 4 + 4 (p <.001), but not GP 3 + 5 (p =.1). Of EBRT patients, 7.6 versus 89.8 versus 2.6% exhibited biopsy GP 3 + 5 versus 4 + 4 versus 5 + 3 and respective 10-year CSM rates were 12.2 versus 13.8 versus 17.8% (p <.001). In multivariable analyses addressing EBRT patients, no CSM differences according to GP were observed (all p ≥.4). Conclusion: In GGG IV RP candidates, the presence of biopsy GP 5 + 3 purports a significantly higher CSM than in GP 4 + 4 or 3 + 5. In GGG IV EBRT candidates, no significant CSM differences according to GP were recorded.