Correlation of modified Gleason grading with pT stage of prostatic carcinoma after radical prostatectomy

OBJECTIVE: To study the correlation between modified Gleason score (GS) and pT stage of radical prostatectomy (RP) specimens. STUDY DESIGN: Six hundred forty-nine consecutive RP specimens were graded according to the conventional and the modified Gleason grading systems. RESULTS: A total of 29% of the tumors were upgraded. Both variants of GS correlated with pathologic stage. Stage pT2 tumors were assigned a GS of 3-6 less often with modified grading than with conventional grading (29% and 84%, respectively). The only significant difference of stage distribution between conventional and modified GS was for GS 7, where pT2 was the most common stage with modified grading (54%) and pT3 was most common with conventional grading (67%). Of GS 3 + 4 = 7a tumors, 95% were stage pT2, while 79% of GS 4 + 3 = 7b tumors were stage pT3-4. CONCLUSION: The stage distribution of modified GSs of RP specimens differs from that of conventional GSs, but a good correlation exists between grade and pT stage. Notably, GS 4 + 3 = 7b was more often associated with high stage than was GS 3 + 4 7a.