[833] Pathology of Organ-Confined (OC), Gleason Score (GS) 6 Prostate Carcinoma with Post-Radical Prostatectomy (RP) Biochemical Progression

H Miyamoto, JI Epstein. Johns Hopkins Hospital, Baltimore

Background: Prior studies of RPs have reported a small percentage of men with biochemical progression after RP showing OC, GS6. One might predict that this should virtually never occur.
Design: We identified 2,551 (1983-2005) RPs coded by the urologists as pathologically OC, GS6 cancer with >1 year follow-up. We reexamined histopathogically the serially sectioned and completely embedded RP specimens of 37 men who developed biochemical recurrence defined as a single PSA level of 0.2 ng/mL.
Results: In 26/37 (70%) of cases, pathology re-review showed higher grade or stage than coded by the urologists. In 10/26 there was OC with Gleason pattern 4 (3 + 4 = 7 in 7 cases; 4 + 3 = 7 in 2 cases; 2 + 4 = 6 in 1 case). There were another 8/26 cases with OC GS 3+3=6 with tertiary pattern 4; in 4 cases, tertiary pattern 4 was described in the initial pathology report but urologists considered the tumor GS 6. 1/26 cases had GS 3+3=6 with focal extraprostatic extension (EPE). 5/26 cases had GS 3+4=7 plus EPE (4 with focal and 1 with non-focal EPE). 2/26 cases had positive margins with capsular incision listed in the report, but were considered by urologists as OC. Undergraded Gleason patterns 4 included glands that were: poorly formed-fused (8 cases); large glomeruloid (2 cases); large irregular cribriform (2 cases); small/medium irregular cribriform (8 cases); and small/medium regular cribriform (4 cases). Undergraded pattern 4 tumor occupied on average 11% of the tumor area. Mean tumor volume of the 11 true OC, GS 6 tumors were 0.33 cm³ (range: 0.02 1.24). Tumor volume was <0.5 cm³ in 9 cases. 6/11 had biochemical progression 8 years following RP, which is unusual. 8/11(5 with radiation) had 0.4 ng/mL as their maximum post-RP PSA value. 2 of these men had maximum post-RP PSA of 0.2 ng/mL with tumor volumes of 0.02 cm³ and 0.07 cm³. 0/11 developed systemic disease.
Conclusions: Most prior reports of OC, GS6 with progression are undergraded (upgrading with revision of Gleason system), understaged (difficulty recognizing focal EPE), or suffer from situations with ambiguous staging (capsular incision) or grading (tertiary pattern 4 or 2+4=6). Even for the rare true OC, GS6 with no pattern 4 tumor with supposed biochemical progression, some may be false positive progression based on low post-RP PSA levels and minute tumors that seem highly improbable to progress. With accurate pathologic evaluation, men with OS, GS6 (no pattern 4) prostate cancer can be told that their risk of progression is exceptionally rare.
Category: Genitourinary (including renal tumors)

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 125, Wednesday Morning