Prostate Cancer Grading: A Decade After the 2005 Modified Gleason Grading System

Since 1966, when Donald Gleason, MD, first proposed grading prostate cancer based on its histologic architecture, there have been numerous changes in clinical and pathologic practices relating to prostate cancer. Patterns 1 and 2, comprising more than 30% of cases in the original publications by Gleason, are no longer reported on biopsy and are rarely diagnosed on radical prostatectomy. Many of these cases may even have been mimickers of prostate cancer that were described later with the use of contemporary immunohistochemistry. The original Gleason system predated many newly described variants of prostate cancer and our current concept of intraductal carcinoma. Gleason also did not describe how to report prostate cancer on biopsy with multiple cores of cancer or on radical prostatectomy with separate tumor nodules. To address these issues, the International Society of Urological Pathology first made revisions to the grading system in 2005, and subsequently in 2014. Additionally, a new grading system composed of Grade Groups 1 to 5 that was first developed in 2013 at the Johns Hopkins Hospital and subsequently validated in a large multi-institutional and multimodal study was presented at the 2014 International Society of Urological Pathology meeting and accepted both by participating pathologists as well as urologists, oncologists, and radiation therapists. In the present study, we describe updates to the grading of prostate cancer along with the new grading system.

SOCS3 immunohistochemical expression to support the 2005 International Society of Urological Pathology (ISUP) modified Gleason grading system.

216 Background: In the 2005 International Society of Urological Pathology (ISUP) Consensus Conference, a modified Gleason grading system for prostate cancer was proposed. (Epstein JI et al. Am J Surg Pathol 2005; 29:1228-1242) Afterwards an interobserver study among experts in genitourinary pathology proposed some modifications and refinements to the 2005 ISUP modified grading system concerning the cribriform pattern carcinoma that it should never be diagnosed as Gleason pattern 3, assigning Gleason pattern 4 to cribriform glands (Latour M et al. Am J Surg Pathol 2008; 32: 1532-1539; Epstein J I Journal of Urology 2010: 183:433-440). Methods: The study population consisted of 80 patients undergoing biopsies at the Institute of Urology of our hospital, between February 2012 and January 2013 stratified into 3 different categories on the basis of histologic pattern: 1) 20 patients with classical and modified Gleason score 3+3 = 6; 2) 30 patients with classical Gleason score 3+3 = 6 upgraded to Gleason score 7 according to the ISUP modified grading system; and 3) 30 patients with classical and modified Gleason score 3+4 = 7. We evaluate the immunohistochemical protein expression of the suppressor of cytokine signaling (SOCS) proteins 3 (SOCS3) in these three different group of prostatic cancer biopsies. Results: We found that the SOCS3 pattern staining negative (-) or with SOCS3 negative staining with weak intensity staining in less than 50% of neoplastic glands (+/-) increases progressively in concomitance with the rise of Gleason score and SOCS3 positivity (+), correlates with classical or modified Gleason score 6 (P = 0,0004 Fisher’s exact tests) and with classical Gleason score 3+3 = 6 upgraded to Gleason score 7 (P = 0,0010 Fisher’s exact tests). Conclusions: In conclusion our data seem to support from a molecular point of view the modified criteria by 2005 International Society of Urological Pathology (ISUP) Consensus Conference as well as the hypothesis that the diagnosis of Gleason cribriform pattern 3 virtually does not exist and cribriform glands-regardless of their size-are nearly always considered pattern 4.

Comparison of Classic and International Society of Urological Pathology 2005 Modified Gleason Grading Using Needle Biopsies From the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) Trial

Context.—Use of the International Society of Urological Pathology (ISUP) 2005 modified Gleason score may result in higher scores compared with the classic Gleason scoring system. Objective.—To compare scores derived using the 2 scoring systems. Design.—On-study and for-cause biopsies were centrally reviewed and assigned a classic Gleason score in the Reduction by Dutasteride of prostate Cancer Events trial. Positive biopsies were reviewed by an independent pathologist in a secondary review using the ISUP 2005 modified Gleason score. The independent pathologist also recorded a classic Gleason score. Results.—In total, 1482/1507 (98%) positive biopsy results were independently reviewed. Scores assigned by the 2 pathologists (classic versus modified) agreed in 83% (1230 of 1481) of cases; 99% (1471 of 1481) of cancers were within ±1 of their previous score. Of discordant cases, similar numbers of biopsies were upgraded and downgraded in the secondary review, with minor differences in the score distributions. Interobserver agreement was good, with κ values ranging from 0.62 (95% confidence interval [CI], 0.56–0.67) to 0.70 (95% CI, 0.65–0.76). The overall number of high-grade tumors (Gleason score 8–10; n = 48) remained constant between reviews, with 3 fewer cases in the placebo group (n = 16) and 3 more in the dutasteride group (n = 32) in the secondary review. When comparing the independent pathologist's modified scores versus the classic, 17 of 1481 cancers (1.1%) were upgraded (including 9 of 17 upgrades [53%] to high-grade tumors). Conclusions.—This analysis showed similar score distributions between the classic and modified Gleason scoring systems. The differences seen between the 2 pathologists' scores likely reflect differences in interpretation rather than the scoring system chosen.