The Absolute Volume of Gleason Pattern 4 on Radical Prostatectomy Is More Strongly Associated With Advanced Stage and Biochemical Recurrence Than Gleason Grade Groups.

PURPOSE: International Society of Urological Pathology (ISUP) Grade Group (GG) is based on the relative proportion of Gleason patterns 3 and 4. We investigated whether absolute pattern 4 volume is more strongly associated with advanced stage and biochemical recurrence than GG in patients with pattern 4 but not 5.

MATERIALS AND

METHODS

Overall, 1171 men received radical prostatectomy. Advanced stage definitions were extraprostatic extension (EPE) or seminal vesicle invasion (SVI) or lymph nodal invasion (LNI), and SVI or LNI. We explored the association between pattern 4 volume and percentage, and GG with advanced stage and recurrence using logistic and Cox regressions. We examined whether incorporating pattern 4 percentage improved the accuracy of a model including pattern 4 volume, PSA, and cT stage.

RESULTS

Overall, 649, 381, and 141 patients had GG2, GG3, and GG4. EPE, SVI, and LNI were in 643, 84, and 57 men. For the EPE, SVI, or LNI outcome, pattern 4 volume showed higher discrimination (0.748) than ISUP (0.693) and pattern 4 percentage (0.724). Results were strengthened when outcome was SVI or LNI and excluded patients without nodal dissection. Pattern 4 volume showed higher discrimination for recurrence (0.705) than ISUP (0.675) or pattern 4 percentage (0.680). Pattern 3 volume did not increase discrimination when added to pattern 4. PSA levels were driven by pattern 4 volume, with pattern 3 and benign volumes having less impact.

CONCLUSIONS

The total amount of pattern 4 provides superior prognostic information to the relative proportion of patterns 3 and 4. Further research should investigate the best pattern 4 quantification method.