Validation of International Society of Urological Pathology (ISUP) grading for prostatic adenocarcinoma in thin core biopsies using TROG 03.04 'RADAR' trial clinical data

Gleason score 3+3=6 prostatic adenocarcinoma is not benign and the current debate is unhelpful to clinicians and patients

Prostate adenocarcinoma is a common malignancy associated with a significant morbidity and mortality. In both prostate biopsies and radical prostatectomy specimens Gleason scoring informs both treatment and outcome prediction. The current convention is that in needle biopsies, Gleason patterns 3, 4 and 5 are considered to be malignant. Despite this there is debate as to whether or not Gleason score (GS) 3+3=6 should be diagnosed as cancer due to potential over-treatment and the psychological impact on patients. It is apparent that GS 3+3=6 is indolent disease with a low risk of metastasis. However, it does have the histological features of malignancy and is capable of infiltrating the prostate gland, extraprostatic extension, and metastatic spread. Furthermore GS 3+3=6 carcinoma has immunohistochemical and molecular genetic features similar to those of higher grade prostatic carcinoma. If GS 3+3=6 tumour is considered benign, the question arises should a benign label be given to the Gleason pattern 3 component of tumour that includes Gleason patterns of higher grade? This would seem a logical step as GS 3+3=6 cancers and the pattern 3 component in cancers with multiple patterns are morphologically identical. If pattern 3 is considered to be benign, then Gleason scoring would be limited to 4+4=8, 4+5=9, 5+4=9 and 5+5=10 which is clearly inappropriate. The correct strategy to address potential over-treatment of patients with low-grade cancer is clinician and patient education, not the recalibration of Gleason grading to reclassify malignant tumours as benign.

International Society of Urological Pathology (ISUP) Gleason Grade Groups stratify outcomes in the CHHiP Phase 3 prostate radiotherapy trial

OBJECTIVES

To compare the results of Gleason Grade Group (GGG) classification following central pathology review with previous local pathology assessment, and to examine the difference between using overall and worst GGG in a large patient cohort treated with radiotherapy and short-course hormone therapy.

PATIENTS AND METHODS

Patients with low- to high-risk localized prostate cancer were randomized into the multicentre CHHiP fractionation trial between 2002 and 2011. Patients received short-course hormone therapy (≤6 month) and radical intensity-modulated radiotherapy (IMRT). Of 2749 consented patients, 1875 had adequate diagnostic biopsy tissue for blinded central pathology review. The median follow-up was 9.3 years. Agreement between local pathology and central pathology-derived GGG and between central pathology-derived overall and worst GGG was assessed using kappa (κ) statistics. Multivariate Cox regression and Kaplan-Meier methods were used to compare the biochemical/clinical failure (BCF) and distant metastases (DM) outcomes of patients with GGG 1-5.

RESULTS

There was poor agreement between local pathology- and central pathology-derived GGG (κ = 0.19) but good agreement between overall and worst GGG on central pathology review (κ = 0.89). Central pathology-derived GGG stratified BCF and DM outcomes better than local pathology, while overall and worst GGG on central pathology review performed similarly. GGG 3 segregated with GGG 4 for BCF, with BCF-free rates of 90%, 82%, 74%, 71% and 58% for GGGs 1-5, respectively, at 8 years when assessed using overall GGG. There was a progressive decrease in DM-free rates from 98%, 96%, 92%, 88% and 83% for GGGs 1-5, respectively, at 8 years with overall GGG. Patients (n = 57) who were upgraded from GGG 2-3 using worst GS had BCF-free and DM-free rates of 74% and 92% at 8 years. CHHiP eligibility criteria limit the interpretation of these results.

CONCLUSION

Contemporary review of International Society of Urological Pathology GGG successfully stratified patients treated with short-course hormone therapy and IMRT with regard to both BCF-free and DM-free outcomes. Patients upgraded from GGG 2 to GGG 3 using worst biopsy GS segregate with GGG 3 on long-term follow-up. We recommend that both overall and worst GS be used to derive GGG.

Prognostic Utility of the Gleason Grading System Revisions and Histopathological Factors Beyond Gleason Grade

Background

The International Society of Urological Pathology (ISUP) revised the Gleason system in 2005 and 2014. The impact of these changes on prostate cancer (PCa) prognostication remains unclear.

Objective

To evaluate if the ISUP 2014 Gleason score (GS) predicts PCa death better than the pre-2005 GS, and if additional histopathological information can further improve PCa death prediction.

Patients and Methods

We conducted a case–control study nested among men in the National Prostate Cancer Register of Sweden diagnosed with non-metastatic PCa 1998–2015. We included 369 men who died from PCa (cases) and 369 men who did not (controls). Two uro-pathologists centrally re-reviewed biopsy ISUP 2014 Gleason grading, poorly formed glands, cribriform pattern, comedonecrosis, perineural invasion, intraductal, ductal and mucinous carcinoma, percentage Gleason 4, inflammation, high-grade prostatic intraepithelial neoplasia (HGPIN) and post-atrophic hyperplasia. Pre-2005 GS was back-transformed using i) information on cribriform pattern and/or poorly formed glands and ii) the diagnostic GS from the registry. Models were developed using Firth logistic regression and compared in terms of discrimination (AUC).

Results

The ISUP 2014 GS (AUC = 0.808) performed better than the pre-2005 GS when back-transformed using only cribriform pattern (AUC = 0.785) or both cribriform and poorly formed glands (AUC = 0.792), but not when back-transformed using only poorly formed glands (AUC = 0.800). Similarly, the ISUP 2014 GS performed better than the diagnostic GS (AUC = 0.808 vs 0.781). Comedonecrosis (AUC = 0.811), HGPIN (AUC = 0.810) and number of cores with ≥50% cancer (AUC = 0.810) predicted PCa death independently of the ISUP 2014 GS.

Conclusion

The Gleason Grading revisions have improved PCa death prediction, likely due to classifying cribriform patterns, rather than poorly formed glands, as Gleason 4. Comedonecrosis, HGPIN and number of cores with ≥50% cancer further improve PCa death discrimination slightly.

Prostate-Specific Antigen Kinetics Effects on Outcomes of Low-Volume Metastatic Prostate Cancer Patients Receiving Androgen Deprivation Therapy

Background

The present study aimed to analyse factors influencing the effects of androgen deprivation therapy (ADT) in patients with newly diagnosed metastatic castration-naïve prostate cancer (mCNPC), especially in low-volume disease (LVD), according to subclassification of metastatic prostate cancer established by the CHAARTED trial.

Materials and Methods

We reviewed 648 patients with newly diagnosed mCNPC receiving ADT at Chang Gung Memorial Hospital from January 2007 to December 2016. Basic characteristics and PSA kinetics profile were subsequently evaluated.

Results

48.3% of LVD patients progressed to castration-resistant prostate cancer (mCRPC). Among them, CRPC group had significantly shorter time to PSA nadir (TTN) and faster time from PSA nadir to CRPC (TFNTC) (p < 0.001) compared to non-CRPC group. PSA doubling time (PSADT) < 4 months tended to be associated with faster disease progression and shorter overall survival (OS). Among all patients with metastatic prostate cancer, those with shorter TTN <9 months, higher nadir PSA level ≥1 ng/mL, and shorter PSADT <3 months had increased tendency for biochemical progression.

Conclusions

PSADT is an effective clinical predictor for disease progression and survival in LVD. Other PSA kinetics including TTN and TFNTC, though not the major predictors for disease progression or OS in LVD, might be the predictors for disease control status.

Assessing ISUP prostate cancer grade groups in patients treated with definitive dose escalated external beam radiation

PURPOSE

The five grade group system has been validated for men treated with radical prostatectomy. However, the prognostic value for men treated with radiation therapy is uncertain, with prior studies utilising old techniques and doses. We aimed to validate the International Society of Urological Pathology (ISUP) groupings for men treated with contemporary radiation therapy.

METHODS

Men with localised prostate cancer treated with image-guided, dose-escalated (≥78 Gy) external beam radiation were identified across four institutions. Primary outcome was time to biochemical failure. Harrell's C index assessed performance of the ISUP system against other grading stratifications.

RESULTS

2205 men were included, withmedian follow-up of 5.6 years. Seven-year actuarial rates of biochemical failure for grade groups 1-5 were 9.3%, 10.4%, 13.2%, 12.4% and 23.4%. On multivariate analysis, hazard ratios for biochemical failure were1.19, 1.00, 1.10, 1.05 and 2.10 for grade groups 1-5, relative to 2. P values were only significant for grade group 5. Harrell's C index favoured an alternative three group model (comprising Gleason scores [6 and 3 + 4 = 7] vs [4 + 3 = 7 and 8] vs [9 and 10]) over ISUP grade groups.

CONCLUSIONS

The ISUP grade groups were not validated in a contemporary cohort treated with dose-escalated, image-guided radiation therapy. Grade groups 1-4 were not statistically different from each other; however, grade group 5 had a significantly worse prognosis. We identified a new three group model that better predicted biochemical outcomes. Further work is requiredto validate optimal groupings for modern radiation therapy and investigate the contrasting prognostic capability of grade groups in surgical and radiation therapy patients.

Narrative review of prostate cancer grading systems: will the Gleason scores be replaced by the Grade Groups?

The Gleason grading system, proposed by Dr. Donald F. Gleason in 1966, is one of the most important prognostic factors in men with prostate cancer (PCa). At consensus conferences held in 2005 and 2014, organized by the International Society of Urological Pathology (ISUP), the system was modified to reflect the current diagnostic and therapeutic approaches. In particular, in the 2014 Conference, it was recognized that there were weaknesses with the original and the 2005 ISUP modified Gleason systems. Based on the results of a research conducted by Prof. JI Epstein and his group, a new grading system was proposed by the ISUP in order to address some of such deficiencies: i.e., the five distinct Grade Groups (GGs). Since 2014, results of studies have been published by different groups and societies, including the Genitourinary Pathology Society (GUPS), giving additional support to the prognostic role of the architectural Gleason patterns and, in particular, of the GGs. A revised GG system, taking into account the percentage of Gleason pattern (GP) 4, cribriform and intraductal carcinoma, tertiary GP 5, and reactive stroma grade, has shown to have some advantages, however not ready for adoption in the current practice. The aim of this contribution was to review the major updates and recommendations regarding the GPs and GSs, as well as the GGs, trying to give an answer to the following questions: “How has the grade group system been used in the routine?” and “will the Gleason scoring system be replace by the grade groups?” We also discussed the potential implementation in the future of molecular pathology and artificial intelligence in grading to further define risk groups in patients with PCa.

Prostate Cancer, Version 2.2019, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Prostate Cancer include recommendations regarding diagnosis, risk stratification and workup, treatment options for localized disease, and management of recurrent and advanced disease for clinicians who treat patients with prostate cancer. The portions of the guidelines included herein focus on the roles of germline and somatic genetic testing, risk stratification with nomograms and tumor multigene molecular testing, androgen deprivation therapy, secondary hormonal therapy, chemotherapy, and immunotherapy in patients with prostate cancer.

Updates in Histologic Grading of Urologic Neoplasms

CONTEXT.—

Tumor histology offers a composite view of the genetic, epigenetic, proteomic, and microenvironmental determinants of tumor biology. As a marker of tumor histology, histologic grading has persisted as a highly relevant factor in risk stratification and management of urologic neoplasms (ie, renal cell carcinoma, prostatic adenocarcinoma, and urothelial carcinoma). Ongoing research and consensus meetings have attempted to improve the accuracy, consistency, and biologic relevance of histologic grading, as well as provide guidance for many challenging scenarios.

OBJECTIVE.—

To review the most recent updates to the grading system of urologic neoplasms, including those in the 2016 4th edition of the World Health Organization (WHO) Bluebook, with emphasis on issues encountered in routine practice.

DATA SOURCES.—

Peer-reviewed publications and the 4th edition of the WHO Bluebook on the pathology and genetics of the urinary system and male genital organs.

CONCLUSIONS.—

This article summarizes the recently updated grading schemes for renal cell carcinoma, prostate adenocarcinomas, and bladder neoplasms of the genitourinary tract.

Perineural invasion by prostate adenocarcinoma in needle biopsies predicts bone metastasis: Ten year data from the TROG 03.04 RADAR Trial

AIMS

Perineural invasion (PNI) by prostatic adenocarcinoma is debated as a prognostic parameter. This study investigates the prognostic predictive value of PNI in a series of patients with locally advanced prostate cancer treated with radiotherapy and androgen deprivation using 10 years outcome data from the TROG 03.04 RADAR trial.

METHODS

Diagnostic prostate biopsies from 976 patients were reviewed and the presence of PNI noted. Patients were followed for 10 years according to the trial protocol or until death. The primary endpoint for the study was time to bone metastasis. Secondary endpoints included time to soft tissue metastasis, transition to castration resistance, prostate cancer-specific mortality and all-cause mortality.

RESULTS

PNI was detected in 449 cases (46%), with 234 cases (24%) having PNI in more than one core. The presence of PNI was significantly associated with higher ISUP grade, clinical T staging category, National Comprehensive Cancer Network risk group, and percent positive biopsy cores. The cumulative probability of bone metastases according to PNI status was significant over the 10 years follow-up interval of the study (log-rank test P < 0.0001). PNI was associated with all endpoints on univariable analysis. After adjusting for baseline clinicopathological and treatment factors, bone metastasis was the only endpoint in which PNI retained its prognostic significance (hazard ratio 1.42, 95% confidence interval 1.05-1.92, P = 0.021).

CONCLUSIONS

The association between PNI and the development of bone metastases supports the inclusion of this parameter as a component of the routine histology report. Further this association suggests that evaluation of PNI may assist in selecting those patients who should be monitored more closely during follow-up.

Identification of areas of grading difficulties in prostate cancer and comparison with artificial intelligence assisted grading

The International Society of Urological Pathology (ISUP) hosts a reference image database supervised by experts with the purpose of establishing an international standard in prostate cancer grading. Here, we aimed to identify areas of grading difficulties and compare the results with those obtained from an artificial intelligence system trained in grading. In a series of 87 needle biopsies of cancers selected to include problematic cases, experts failed to reach a 2/3 consensus in 41.4% (36/87). Among consensus and non-consensus cases, the weighted kappa was 0.77 (range 0.68-0.84) and 0.50 (range 0.40-0.57), respectively. Among the non-consensus cases, four main causes of disagreement were identified: the distinction between Gleason score 3 + 3 with tangential cutting artifacts vs. Gleason score 3 + 4 with poorly formed or fused glands (13 cases), Gleason score 3 + 4 vs. 4 + 3 (7 cases), Gleason score 4 + 3 vs. 4 + 4 (8 cases) and the identification of a small component of Gleason pattern 5 (6 cases). The AI system obtained a weighted kappa value of 0.53 among the non-consensus cases, placing it as the observer with the sixth best reproducibility out of a total of 24. AI may serve as a decision support and decrease inter-observer variability by its ability to make consistent decisions. The grading of these cancer patterns that best predicts outcome and guides treatment warrants further clinical and genetic studies. Results of such investigations should be used to improve calibration of AI systems.

Risk factors for progression to castration-resistant prostate cancer in metastatic prostate cancer patients

Purpose: To investigate the risk factors for progression to castration-resistant prostate cancer (CRPC) in metastatic prostate cancer (mPCa) patients who underwent androgen deprivation therapy (ADT).

Methods: We analyzed 216 patients with mPCa who underwent ADT between January 2006 and December 2015 at the First Affiliated Hospital of Fujian Medical University. Univariate and multivariate Cox regression analysis were used to explore the risk factors for progression to CRPC. Kaplan-Meier analysis and log-rank test were used to evaluate the difference in progression-free survival (PFS).

Results: A total of 121 (56.0%) patients who underwent ADT showed progression to CRPC. Multivariate Cox regression analysis demonstrated that Gleason grade group, prostate-specific antigen nadir (nPSA), and time to PSA nadir (TTN) were risk factors for progression to CRPC in mPCa patients. Kaplan-Meier analysis demonstrated that patients in Gleason grade group ≥3, nPSA >0.2 ng/ml and TTN <6 months had shorter PFS.

Conclusion: This study demonstrated that Gleason grade group, nPSA and TTN were risk factors for progression to CRPC. Patients with higher Gleason grade group, higher nPSA and shorter TTN have shorter PFS and higher risk of progression to CRPC after ADT.

Concordance of "Case Level" Global, Highest, and Largest Volume Cancer Grade Group on Needle Biopsy Versus Grade Group on Radical Prostatectomy

The practice of assigning "case level" biopsy Grade Group (GG) or Gleason Score is variable. To our knowledge, a comparison of the concordance of different biopsy "case level" GG with the prostatectomy GG has not been done in a post-2005 prostate cancer cohort. We evaluated the GG in 2527 patients who had biopsy and radical prostatectomy performed at our institution between 2005 and 2014. We compared the agreements, the upgrades, and the downgrades of 3 different "case level" biopsy GG, with the final GG: (1) Global GG (sum of most prevalent and highest Gleason grade in any biopsy part/site-specific specimen); (2) Highest GG (found in any biopsy part/site-specific specimen); and (3) Largest Volume Cancer GG (found in any biopsy part/site-specific specimen). The concordance between the biopsy and the final GG were evaluated using weighted kappa (κ) coefficient. The biopsy Global GG, Highest GG, and Largest Volume Cancer GG were the same as the final GG in 60.4%, 57.1%, and 54.3% cases, respectively (weighted κ values: 0.49, 0.48, and 0.44, respectively). When final GG contained tertiary 5, the overall GG agreement decreased: Global GG 41.5%, Highest GG 40.3%, and Largest Volume Cancer GG 37.1% (weighted κ: 0.22, 0.21, and 0.18, respectively). A subset analysis for cases in which the biopsy Global GG and Highest GG were different (n=180) showed an agreement of 62.4% (weighted κ: 0.37) and 18.8% (weighted κ: 0.16), respectively. In patients without a tertiary Gleason pattern on radical prostatectomy, the Global GG and the Highest GG were identical in 92.4% of biopsies. Assigning a biopsy "case level" Global GG versus using the Highest GG and the Largest Volume Cancer GG resulted in comparable and slightly improved agreement with the final GG in this cohort.

The validation of the 2014 International Society of Urological Pathology (ISUP) grading system for patients with high-risk prostate cancer: a single-center retrospective study

Introduction

Since the new 2014 grading system was recommended by the International Society of Urological Pathology (ISUP), it has been validated in patients with localized prostate cancer (PCa) and it has shown excellent prognostic value. However, its predictive power in high-risk PCa remains unclear.

Methods

A total of 420 patients with high-risk PCa who underwent radical prostatectomy (RP) were included in this study. Biochemical recurrence-free survival (BRFS) was set as the endpoint.

Results

Biochemical recurrence occurred in 84/420 (20.0%) patients at the end of follow-up. Compared to the three-tier grouping system, the five-tier grouping system could more effectively distinguish the BRFS of patients with higher predictive accuracy (C-index: 0.599 vs 0.646). The BRFS of patients with grade group (GG) 1 and GG 2 was similar (P=0.593). Also, the prognosis between those with GG 2 and GG 3 could be clearly distinguished (P=0.001). However, the discrimination capacity between patients with GG 3 and GG 4 was limited (P=0.681). When tertiary Gleason pattern (TGP5) and intraductal carcinoma of the prostate (IDC-P) were excluded, the HR value of the GG 4 group vs the GG 3 group increased from 1.15 (95% CI: 0.59–2.22) to 1.49 (95% CI: 0.72–3.10) and 1.36 (95% CI:0.65–2.83), respectively.

Conclusions

This study is the first to validate the new 2014 ISUP grading system in patients with high-risk PCa who underwent RP. The 2014 system could effectively classify patients into five groups with high predictive accuracy. Notably, the existence of TGP5 and IDC-P needs to be routinely reported in clinical practice, which could help to support the predictive value of the new grading system.

Controversial issues in Gleason and International Society of Urological Pathology (ISUP) prostate cancer grading: proposed recommendations for international implementation

The Gleason Grading system has been used for over 50 years to prognosticate and guide the treatment for patients with prostate cancer. At consensus conferences in 2005 and 2014 under the guidance of the International Society of Urological Pathology (ISUP), the system has undergone major modifications to reflect modern diagnostic and therapeutic practices. The 2014 consensus conference yielded recommendations regarding cribriform, mucinous, glomeruloid and intraductal patterns, the most significant of which was the removal of any cribriform pattern from Gleason grade 3. Furthermore, a Gleason score grouping system was endorsed which consisted of five grades where Gleason score 6 (3+3) was classified as grade 1 which better reflected the mostly indolent behaviour of these tumours. Another issue discussed at the meeting and subsequently endorsed was that in Gleason score 7 cases, the percentage pattern 4 should be recorded. This is especially important in situations where modern active surveillance protocols expand to include men with low volume pattern 4. While major progress was made at the conference, several issues were either not resolved or not discussed at all. Most of these items relate to details of assignment of Gleason score and ISUP grade in specific specimen types and grading scenarios. This detailed review looks at the 2014 ISUP conference results and subsequent literature from an international perspective and proposes several recommendations. The specific issues addressed are percentage pattern 4 in Gleason score 7 tumours, percentage patterns 4 and 5 or 4/5 in Gleason score 8-10 disease, minor (≤5%) high grade patterns when either 2 or 3 patterns are present, level of reporting (core, specimen, case), dealing with grade diversity among site (highest and composite scores) and reporting scores in radical prostatectomy specimens with multifocal disease. It is recognised that for many of these issues, a strong evidence base does not exist, and further research studies are required. The proposed recommendations mostly reflect consolidated expert opinion and they are classified as established if there was prior agreement by consensus and provisional if there was no previous agreement or if the item was not discussed at prior consensus conferences. For some items there are reporting options that reflect the local requirements and diverse practice models of the international urological pathology community. The proposed recommendations provide a framework for discussion at future consensus meetings.

Essential Updates in Grading, Morphotyping, Reporting, and Staging of Prostate Carcinoma for General Surgical Pathologists

CONTEXT.—

Within this decade, several important updates in prostate cancer have been presented through expert international consensus conferences and influential publications of tumor classification and staging.

OBJECTIVE.—

To present key updates in prostate carcinoma.

DATA SOURCES.—

The study comprised a review of literature and our experience from routine and consultation practices.

CONCLUSIONS.—

Grade groups, a compression of the Gleason system into clinically meaningful groups relevant in this era of active surveillance and multidisciplinary care management for prostate cancer, have been introduced. Refinements in the Gleason patterns notably result in the contemporarily defined Gleason score 6 cancers having a virtually indolent behavior. Grading of tertiary and minor higher-grade patterns in radical prostatectomy has been clarified. A new classification for prostatic neuroendocrine tumors has been promulgated, and intraductal, microcystic, and pleomorphic giant cell carcinomas have been officially recognized. Reporting the percentage of Gleason pattern 4 in Gleason score 7 cancers has been recommended, and data on the enhanced risk for worse prognosis of cribriform pattern are emerging. In reporting biopsies for active surveillance criteria-based protocols, we outline approaches in special situations, including variances in sampling or submission. The 8th American Joint Commission on Cancer TNM staging for prostate cancer has eliminated pT2 subcategorization and stresses the importance of nonanatomic factors in stage groupings and outcome prediction. As the clinical and pathology practices for prostate cancer continue to evolve, it is of utmost importance that surgical pathologists become fully aware of the new changes and challenges that impact their evaluation of prostatic specimens.

Updates on Grading and Staging of Prostate Cancer

Since its development between 1966 and 1977, the Gleason grading system has remained one of the most important prognostic indicators in prostatic acinar adenocarcinoma. The grading system was first majorly revised in 2005 and again in 2014. With the publication of the 8th edition of the American Joint Committee on Cancer TNM staging manual in 2018, the classification of prostate cancer and its reporting have further evolved and are now included as part of staging criteria. This article reflects the aspects that are most influential on daily practice. A brief summary of 3 ancillary commercially available genomic tests is also provided.

Histopathology of Prostate Cancer

This review focuses on histopathological aspects of carcinoma of the prostate. A tissue diagnosis of adenocarcinoma is often essential for establishing a diagnosis of prostate cancer, and the foundation for a tissue diagnosis is currently light microscopic examination of hematoxylin and eosin (H&E)-stained tissue sections. Markers detected by immunohistochemistry on tissue sections can support a diagnosis of adenocarcinoma that is primary in the prostate gland or metastatic. Histological variants of carcinoma of the prostate are important for diagnostic recognition of cancer or as clinicopathologic entities that have prognostic and/or therapeutic significance. Histological grading of adenocarcinoma of the prostate, including use of the 2014 International Society of Urological Pathology (ISUP) modified Gleason grades and the new grade groups, is one of the most powerful prognostic indicators for clinically localized prostate cancer, and is one of the most critical factors in determination of management of these patients.

Oncological outcomes in an Australian cohort according to the new prostate cancer grading groupings

Background

A new 5-tiered grading grouping system has recently been endorsed for reporting of prostate cancer (PCa) grade to better reflect escalating risk of progression and cancer death. While several validations of the new grade groupings have been undertaken, most have involved centralised pathological review by specialist urological pathologists.

Methods

Participants included 4268 men with non-metastatic PCa diagnosed between 2006 and 2013 from the multi-institutional South Australia Prostate Cancer Clinical Outcomes Collaborative registry. PCa-specific survival and biochemical recurrence-free survival were compared across the five grade groups using multivariable competing risk regression.

Results

For the entire cohort, risk of PCa death increased with increasing grade groups (at biopsy) Adjusted subdistribution-hazard ratios [sHR] and 95% confidence intervals [95%CI] were: 2.2 (1.5–3.6); 2.5 (1.6–4.2); 4.1 (2.6–6.7) and 8.7 (4.5–14.0) for grade groups II (pattern 3 + 4), III (pattern 4 + 3), IV (total score 8) and V (total score 9–10) respectively, relative to grade group I (total score < =6). Clear gradients in risk of PCa death were observed for radical prostatectomy (RP), but were less clear for those who had radiotherapy (RT) with curative intent and those who were managed conservatively. Likewise, risk of biochemical recurrence increased across grade groups, with a strong and clear gradient for men undergoing RP [sHR (95%CI): 2.0 (1.4–2.8); 3.8 (2.9–5.9); 5.3 (3.5–8.0); 11.2 (6.5–19.2) for grade groups II, III, IV and V respectively, relative to grade group I], and a less clear gradient for men undergoing RT.

Conclusion

In general, the new five-tiered grade groupings distinguished PCa survival and recurrence outcomes for men with PCa. The absence of a clear gradient for RT may be due to heterogeneity in this patient group.

Contemporary grading of prostate cancer: 2017 update for pathologists and clinicians

The Gleason grading system for prostate cancer (PCa) was developed in the 1960s by DF Gleason. Due to changes in PCa detection and treatment, the application of the Gleason grading system has changed considerably in pathology routine practice. Two consensus conferences were held in 2005 and in 2014 to update PCa Gleason grading. This review provides a summary of the changes in the grading of PCa from the original Gleason grading system to the prognostic grade grouping, as well as a discussion of the clinical significance of the percentage of Gleason patterns 4 and 5.

Prognostic Significance of Percentage and Architectural Types of Contemporary Gleason Pattern 4 Prostate Cancer in Radical Prostatectomy

The International Society of Urological Pathology (ISUP) 2014 consensus meeting recommended a novel grade grouping for prostate cancer that included dividing Gleason score (GS) 7 into grade groups 2 (GS 3+4) and 3 (GS 4+3). This division of GS 7, essentially determined by the percent of Gleason pattern (GP) 4 (< or >50%), raises the question of whether a more exact quantification of the percent GP 4 within GS 7 will yield additional prognostic information. Modifications were also made by ISUP regarding the definition of GP 4, now including 4 main architectural types: cribriform, glomeruloid, poorly formed, and fused glands. This study was conducted to analyze the prognostic significance of the percent GP 4 and main architectural types of GP 4 according to the 2014 ISUP grading criteria in radical prostatectomies (RPs). The cohort included 585 RP cases of GS 6 (40.2%), 3+4 (49.0%), and 4+3 (10.8%) prostate cancers. Significantly different 5-year biochemical recurrence (BCR)-free survival rates were observed among GS 6 (99%, 95% confidence interval [CI]: 97%-100%), 3+4 (81%, 95% CI: 76%-86%), and 4+3 (60%, 95% CI: 45%-71%) cancers (P<0.01). Dividing the GP 4 percent into quartiles showed a 5-year BCR-free survival of 84% (95% CI: 78%-89%) for 1% to 20%, 74% (95% CI: 62%-83%) for 21% to 50%, 66% (95% CI: 50%-78%) for 51% to 70%, and 32% (95% CI: 9%-59%) for >70% (P<0.001). Among the GP 4 architectures, cribriform was the most prevalent (43.7%), and combination of architectures with cribriform present was more frequently observed in GS 4+3 (60.3%). Glomeruloid was mostly (67.1%) seen combined with other GP 4 architectures. Unlike the other GP 4 architectures, glomeruloid as the sole GP 4 was observed only as a secondary pattern (ie, 3+4). Among patients with GS 7 cancer, the presence of cribriform architecture was associated with decreased 5-year BCR-free survival when compared with GS 7 cancers without this architecture (68% vs. 85%, P<0.01), whereas the presence of glomeruloid architecture was associated with improved 5-year BCR-free survival when compared with GS 7 cancers without this architecture (87% vs. 75%, P=0.01). However, GS 7 disease having only the glomeruloid architecture had significantly lower 5-year BCR-free survival than GS 6 cancers (86% vs. 99%, P<0.01). Multivariable Cox proportional hazards regression model for factors associated with BCR among GS 7 cancers identified age (hazard ratio [HR] 0.95, P<0.01), preoperative prostate-specific antigen (HR 1.07, P<0.01), positive surgical margin (HR 2.70, P<0.01), percent of GP 4 (21% to 50% [HR 2.21], 51% to 70% [HR 2.59], >70% [HR 6.57], all P<0.01), presence of cribriform glands (HR 1.78, P=0.02), and presence of glomeruloid glands (HR 0.43, P=0.03) as independent predictors. In conclusion, our study shows that increments in percent of GP 4 correlate with increased risk for BCR supporting the ISUP recommendation of recording the percent of GP 4 in GS 7 prostate cancers at RP. However, additional larger studies are needed to establish the optimal interval for reporting percent GP 4 in GS 7 cancers. Among the GP 4 architectures, cribriform independently predicts BCR, whereas glomeruloid reduces the risk of BCR. Distinction should be made between cribriform and glomeruloid architectures, despite glomeruloid being considered as an early stage of cribriform, as cribriform confers a higher risk for poorer outcome.

Gleason grade grouping of prostate cancer is of prognostic value in Asian men

AIM

The International Society of Urological Pathology made recommendations for the use of Grade Groups (GG) originally described by Epstein and colleagues over Gleason score (GS) alone in 2014, which was subsequently adopted by the WHO classification in 2016. The majority of studies validating this revision have been in Caucasian populations. We therefore asked whether the new GG system was retrospectively associated with biochemical disease-free survival in a mixed-ethnicity cohort of Asian men.

METHODS

A total of 680 radical prostatectomies (RPs) from 2005 to 2014 were included. GS from initial biopsy and RP were compared and used to allocate cases to GG, defined as: 1 (GS≤6); 2 (GS 3+4=7); 3 (GS 4+3=7); 4 (GS 4+4=8/5+3=8/3+5=8) and 5 (GS 9-10). Biochemical recurrence was defined as two consecutive post-RP prostate-specific antigen (PSA) levels of >0.2 ng/mL after post-RP PSA reaching the nadir of <0.1 ng/mL.

RESULTS

Our data showed that Kaplan-Meier analysis revealed significant differences in biochemical recurrence within Gleason GG based on either biopsy or prostatectomy scoring. Multivariate analysis further confirmed that a higher GG was significantly associated with risk of biochemical recurrence. This GG system had a higher prognostic discrimination for both initial biopsy and RP than GS.

CONCLUSIONS

Our study validates the use of the revised and updated GG system in a mixed-ethnicity population of Asian men. Higher GG was significantly associated with increased risk of biochemical recurrence. We therefore recommend its use to inform clinical management for patients with prostate cancer.

Prostate cancer: from Gleason scoring to prognostic grade grouping

The Gleason grading system was developed in the late 1960s by Dr. Donald F. Gleason. Due to changes in prostatic adenocarcinoma (PAC) detection and treatment, newer technologies to better characterize prostatic pathology, subsequently described variants of PAC and further data relating various morphologic patterns to prognosis, the application of the Gleason grading system changed substantially in surgical pathology. First in 2005 and more recently in 2014, consensus conferences were held to update PAC grading. Here, we review of the successive changes in the grading of PAC from the original system, with emphasis on the newest prognostic grade grouping.

One is the new six: The International Society of Urological Pathology (ISUP) patient-focused approach to Gleason grading

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Predictive efficacy of the 2014 International Society of Urological Pathology Gleason grading system in initially diagnosed metastatic prostate cancer

We compared the predictive ability of the 2014 and 2005 Gleason grading systems in 568 patients initially diagnosed with metastatic prostate cancer (PCa). Outcomes included the duration of castration-resistant prostate cancer-free survival (CFS) and overall survival (OS). Univariate analyses and log-rank tests were used to identify prognosis indicators and assess univariable differences in CFS and OS in Gleason score (GS) groups. Cox proportional hazards and area under the curves of receiver operator characteristics methods were used to evaluate the predictive efficacy of the 2005 and 2014 ISUP grading systems. Univariate analyses showed that the 2005 and 2014 grading systems were prognosticators for CFS and OS; both systems could distinguish the clinical outcome of patients with GS 6, GS 7, and GS 8–10. Using the 2014 criteria, no statistical differences in patient survival were observed between GS 3 + 4 and GS 4 + 3 or GS 8 and GS 9–10. The predictive ability of the 2014 and 2005 grading systems was comparable for CFS and OS (P = 0.321). However, the 2014 grading system did not exhibit superior predictive efficacy in patients initially diagnosed with PCa and bone metastasis; trials using larger cohorts are required to confirm its predictive value. To the best of our knowledge, ours is the first study to compare the 2005 and 2014 grading systems in initially diagnosed PCa with bone metastasis. At present, we recommend that both systems should be used to predict the prognosis of patients with metastatic PCa.

From Gleason to International Society of Urological Pathology (ISUP) grading of prostate cancer

Gleason grading of prostate cancer has gained worldwide acceptance since its introduction 50 years ago. This system has fulfilled the role of a powerful prognostic indicator for many years and this has influenced treatment. There have been numerous changes to the management and diagnosis of prostate cancer since 1966, including prostate-specific antigen screening, resulting in the early detection of prostate cancer, This has resulted in the evolution of Gleason grading with the informal adoption of a number of alterations. Significant changes to Gleason grading were made in 2005 through a consensus conference convened by the International Society of Urological Pathology (ISUP). In more recent times, the necessity for further changes to prostate cancer grading has been apparent and a follow-up ISUP consensus conference was held in 2014. Changes resulting from this conference included the classifying of all cribriform cancer and glomeruloid patterns as Gleason grade 4, the grading of mucinous adenocarcinoma based on underlying architecture rather than uniformly considering these tumors as pattern 4, and the introduction of a Gleason score (GS)-based 5 grade system, which incorporated the 2014 modifications to the Gleason grading system. Designated ISUP grade, this system consists of five grades: grade 1 (GS ≤3 + 3), grade 2 (GS 3 + 4), grade 3 (GS 4 + 3), grade 4 (GS 4 + 4, 3 + 5, 5 + 3) and grade 5 (GS 9-10). With further advances recently reported in the literature, it is apparent that amendments to the current system are likely to be necessary in the future.

International Society of Urological Pathology (ISUP) grading of prostate cancer - An ISUP consensus on contemporary grading

The International Society of Urological Pathology (ISUP) has issued guidelines for the grading of prostate cancer based on a consensus conference held in 2014. The recommendations resulting from the 2014 consensus conference were a further development of 2005 ISUP modified Gleason grading. In the 2014 system, morphological criteria are clarified, including updated definitions of Gleason pattern 4. In addition to the continued reporting of Gleason scores, we also recommend that Gleason scores ≤6, 3 + 4 = 7, 4 + 3 = 7, 8 and 9-10, respectively, be reported as five groups, i.e. ISUP grades 1-5. This new grading system has the dual benefit of predicting patient outcome as well as facilitating patient communication.

Gleason and Fuhrman no longer make the grade

Grading is an important prognostic parameter for prostate adenocarcinoma and renal cell carcinoma (RCC); however, the most frequently used classifications fail to account for advances in our understanding of the diagnostic features, classification and/or behaviour of these tumours. In 2005 and 2014, the International Society of Urological Pathology (ISUP) proposed changes to Gleason scoring with the adoption of the ISUP grading for prostate cancer in 2014 (grade 1, score 3 + 3; grade 2, score 3 + 4; grade 3, score 4 + 3; grade 4, score 8; grade 5, score 9-10). Internationally the Fuhrman grading system is widely employed despite criticisms related to its application, validity, and reproducibility. In 2012, the ISUP established a grading system for RCC (grade 1, the nucleolus is not seen or is inconspicuous and basophilic at ×400 magnification; grade 2, nucleoli are eosinophilic and clearly visible at ×400 magnification; grade 3, nucleoli are clearly visible at ×100 magnification; grade 4, tumours show extreme pleomorphism or rhabdoid and/or sarcomatoid morphology). This grading has been validated for clear cell RCC and papillary RCC. It was further recommended that chromophobe RCC not be graded. For other morphotypes of RCC, ISUP grading has not been validated as a prognostic parameter, but can be used for descriptive purposes.