[997] Do Adenocarcinomas of the Prostate with Gleason Score (GS) ≤6 Have the Potential To Metastasize to Lymph Nodes?

Hillary M Ross, Oleksandr N Kryvenko, Jeffry P Simko, Thomas M Wheeler, Jonathan I Epstein. The Johns Hopkins Hospital, Baltimore; Baylor College of Medicine, Houston; Henry Ford Hospital, Detroit; UCSF, San Francisco

Background: Although rare, GS≤6 in radical prostatectomies (RP) have been reported with pelvic lymph node (LN) metastases. However, there are no studies as to whether pelvic LN metastases occur in tumors GS≤6 using the ISUP modified Gleason scoring system.
Design: We searched the RP databases at 4 large academic centers for entirely submitted RPs GS≤6. 14,444 cases from 1975-2010 were identified. Cases from Institution #1 were split into two groups with December 2004 as the breakpoint, reflecting when the modified ISUP Gleason grading scheme was in press.
Results: Institution #1: 10,935 men were identified with GS≤6 at RP: 7,332 pre-ISUP and 3,603 post-ISUP. In the pre-ISUP group, there were 19 (0.26%) cases with positive LNs, whereas there was only 1 case (0.03%) with a positive LN in the post-ISUP group. 18/19 pre-ISUP cases had non-focal extraprostatic extension (EPE) with 4 invading seminal vesicles. The 1 post-ISUP case had focal EPE. Histological review of 17/19 cases (2 cases unavailable for review) pre-ISUP and the one post-ISUP case showed higher grade than originally reported. Of the 17 pre-ISUP reviewed cases, 3 were upgraded to 4+3=7 with small/large cribriform and poorly formed glands. 10 cases were upgraded to 3+4=7 with either glomeruloid structures, small/large cribriform glands, or ductal features. 3 cases had tertiary pattern 4 with small cribriform glands. 1 case had a prominent colloid component that had been previously left ungraded that currently would be graded as 4+5=9 with large cribriform glands and solid sheets of cells within mucin. The single post-ISUP case had a cribriform gland of tertiary pattern 4. Institutions 2-4: Out of 3,509 men with GS ≤6 at RP, 1 pre-ISUP (slides not available for review) and 1 post-ISUP had a positive LN. The post-ISUP case was called 3+4=7 on biopsy. Although the RP was initially graded as 3+3=6, review showed GS 3+4=7 with small cribriform glands.
Conclusions: Under-grading primarily accounts for lymph node positivity with GS ≤6, which has decreased significantly since the adoption of the ISUP grading system in 2005. Out of over 14,000 totally embedded RPs from multiple institutions, there was not a single case of a GS≤6 tumor with LN metastases. In contrast to prevailing assumptions, Gleason score ≤6 tumors do not appear to metastasize to lymph nodes. Rather, Gleason patterns 4 or 5, as better defined by the current ISUP modified grading system, is required for metastatic disease.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 2:00 PM

Platform Session: Section A, Monday Afternoon


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