Reproducibility and Prognostic Performance of the 1973 and 2004 World Health Organization Classifications for Grade in Non-muscle-invasive Bladder Cancer: A Multicenter Study in 328 Bladder Tumors

Impact of pathologic re-review on grade, clinical stage, and risk stratification for patients with nonmuscle invasive bladder cancer

OBJECTIVES

Pathologic re-review of transurethral resection of bladder tumor (TURBT) specimen is a common practice at our tertiary care center, but its impact on disease risk stratification remains unknown. We sought to determine how pathologic re-review of specimen initially read at an outside institution changed grade, clinical T (cT) stage, and AUA non-muscle-invasive bladder cancer (NMIBC) risk stratification.

METHODS AND MATERIALS

The laboratory information system was searched for patients who underwent TURBT from 2021 to 2022, yielding 561 records. 173 patients met inclusion criteria: 113 with

RESULTS

For

CONCLUSIONS

Re-review of TURBT pathology by a dedicated GU pathologist led to change in AUA NMIBC risk stratification in over one-fifth of patients, with potential for changing management.

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Key Words

• Non-muscle-invasive bladder cancer
• Pathologic grade
• Risk stratification

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MESH Headings

• Humans
• Urinary Bladder Neoplasms/pathology
• Risk Assessment/methods
• Neoplasm Staging
• Male
• Neoplasm Grading
• Female
• Aged
• Neoplasm Invasiveness
• Middle Aged
• Retrospective Studies
• Aged, 80 and over

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Affiliation(s)

Rebecca A Campbell Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Andrew Wood Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Patrick D Michael Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
David Shin Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Nikhil Pramod Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Samuel C Haywood Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Mohamed Eltemamy Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Christopher Weight Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Georges-Pascal Haber Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Byron Lee Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Jonathan Myles Department of Anatomic Pathology, Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH
Jesse McKenney Department of Anatomic Pathology, Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH
Jane Nguyen Department of Anatomic Pathology, Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH
Sean R Williamson Department of Anatomic Pathology, Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH
Christopher Przybycin Department of Anatomic Pathology, Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH
Reza Alaghehbandan Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH
Nima Almassi Glickman Urologic and Kidney Institute, Cleveland Clinic, Cleveland, OH.

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International Society of Urological Pathology (ISUP) Consensus Conference on Current Issues in Bladder Cancer. Working Group 1: Comparison of Bladder Cancer Grading System Performance

Grade is a key prognostic factor in determining progression in nonmuscle invasive papillary urothelial carcinomas. The 2 most common grading methods in use worldwide are the World Health Organization (WHO) 2004 and 1973 schemes. The International Society of Urological Pathology (ISUP) organized the 2022 consensus conference in Basel, Switzerland on current issues in bladder cancer and tasked working group 1 to make recommendations for future iterations of bladder cancer grading. For this purpose, the ISUP developed in collaboration with the European Association of Urology a 10-question survey for their memberships to understand the current use of grading schemes by pathologists and urologists and to ascertain the areas of potential improvements. An additional survey was circulated to the ISUP membership for their opinion on interobserver variability in grading, reporting of urine cytology, and challenges encountered in grade assignment. Comprehensive literature reviews were performed on bladder cancer grading prognosis and interobserver variability along with The Paris System for urine cytology. There are notable differences in practice patterns between North American and European pathologists in terms of used grading scheme and diagnosis of papillary urothelial neoplasm of low malignant potential. Areas of common ground include difficulty in grade assignment, a desire to improve grading criteria, and a move towards subclassifying high-grade urothelial carcinomas. The surveys and in-person voting demonstrated a strong preference to refine current grading into a 3-tier scheme with the division of WHO 2004 high grade into clinically relevant categories. More variable opinions were voiced regarding the use of papillary urothelial carcinoma with low malignant potential.

International Opinions on Grading of Urothelial Carcinoma: A Survey Among European Association of Urology and International Society of Urological Pathology Members

Background

Grade of non-muscle-invasive bladder cancer (NMIBC) is an important prognostic factor for progression. Currently, two World Health Organization (WHO) classification systems (WHO1973, categories: grade 1-3, and WHO2004 categories: papillary urothelial neoplasm of low malignant potential [PUNLMP], low-grade [LG], high-grade [HG] carcinoma) are used.

Objective

To ask the European Association of Urology (EAU) and International Society of Urological Pathology (ISUP) members regarding their current practice and preferences of grading systems.

Design setting and participants

A web-based, anonymous questionnaire with ten questions on grading of NMIBC was created. The members of EAU and ISUP were invited to complete an online survey by the end of 2021. Thirteen experts had previously answered the same questions.

Outcome measurements and statistical analysis

The submitted answers from 214 ISUP members, 191 EAU members, and 13 experts were analyzed.

Results and limitations

Currently, 53% use only the WHO2004 system and 40% use both systems. According to most respondents, PUNLMP is a rare diagnosis with management similar to Ta-LG carcinoma. The majority (72%) would consider reverting back to WHO1973 if grading criteria were more detailed. Separate reporting of WHO1973-G3 within WHO2004-HG would influence clinical decisions for Ta and/or T1 tumors according the majority (55%). Most respondents preferred a two-tier (41%) or a three-tier (41%) grading system. The current WHO2004 grading system is supported by a minority (20%), whereas nearly half (48%) supported a hybrid three- or four-tier grading system composed of both WHO1973 and WHO2004. The survey results of the experts were comparable with ISUP and EAU respondents.

Conclusions

Both the WHO1973 and the WHO2004 grading system are still widely used. Even though opinions on the future of bladder cancer grading were strongly divided, there was limited support for WHO1973 and WHO2004 in their current formats, while the hybrid (three-tier) grading system with LG, HG-G2, and HG-G3 as categories could be considered the most promising alternative.

Patient summary

Grading of non-muscle-invasive bladder cancer (NMIBC) is a matter of ongoing debate and lacks international consensus. We surveyed urologists and pathologists of European Association of Urology and International Society of Urological Pathology on their preferences regarding NMIBC grading to generate a multidisciplinary dialogue. Both the "old" World Health Organization (WHO) 1973 and the "new" WHO2004 grading schemes are still used widely. However, continuation of both the WHO1973 and the WHO2004 system showed limited support, while a hybrid grading system composed of both the WHO1973 and the WHO2004 classification system may be considered a promising alternative.

The impact of grading scheme on non-muscle invasive bladder cancer progression: potential utility of hybrid grading schemes

Non-muscle invasive bladder cancer (NMIBC) grade is a major determinant of progression risk. The most widely utilised grading systems are the World Health Organization (WHO) 1973 and 2004 schemes. Recent publications suggest the utility of combining both into a four-tier or a hybrid three-tier system, subdividing WHO 2004 high grade into two separate categories while maintaining low grade as a single group. We identified two retrospective cohorts of bladder resections/biopsies of papillary urothelial NMIBC with long term clinical follow-up. The sentinel specimen was assessed for WHO 2004 and 1973 grade, along with pathological stage and carcinoma in situ. Each case was additionally stratified into a hybrid three-tier system (low grade; high grade, grades 2 and 3) and a four-tier system (low grade, grades 1 and 2; high grade, grades 2 and 3). Uni- and multivariable analysis for progression and event free survival (PFS/EFS) were calculated along with the time dependent area under the curve (AUC) for each grading scheme. There were 609 cases (Cohort A, n=343; Cohort B, n=266), including 449 (74%) pTa, 156 pT1 (26%) and four pTx with 338 (56%) low grade (177, grade 1; 161, grade 2) and 271 (44%) high grade (137, grade 2; 134, grade 3). A total of 108 patients progressed (17.7%): 97 high grade, (grade 3, n=59; grade 2, n=38). Multivariable analyses of PFS with the hybrid 3- and 4-tier systems showed higher Harrell's concordance indices (0.851 and 0.853, respectively) than WHO 1973 (0.844) and WHO 2004 (0.846). In both cohorts AUC values were higher (0.77-0.85) for the two hybrid grading systems compared to WHO 1973 or WHO 2004 (0.72-0.82). Similar results were seen on analysis of EFS. The data support the use of a hybrid three-tier or four-tier grading system to improve stratification of NMIBC patients.

Diagnostic and prognostic implications of a three-antibody molecular subtyping algorithm for non-muscle invasive bladder cancer

Intrinsic molecular subtypes may explain marked variation between bladder cancer patients in prognosis and response to therapy. Complex testing algorithms and little attention to more prevalent, early‐stage (non‐muscle invasive) bladder cancers (NMIBCs) have hindered implementation of subtyping in clinical practice. Here, using a three‐antibody immunohistochemistry (IHC) algorithm, we identify the diagnostic and prognostic associations of well‐validated proteomic features of basal and luminal subtypes in NMIBC. By IHC, we divided 481 NMIBCs into basal (GATA3⁻/KRT5⁺) and luminal (GATA3⁺/KRT5 variable) subtypes. We further divided the luminal subtype into URO (p16 low), URO‐KRT5⁺ (KRT5⁺), and genomically unstable (GU) (p16 high) subtypes. Expression thresholds were confirmed using unsupervised hierarchical clustering. Subtypes were correlated with pathology and outcomes. All NMIBC cases clustered into the basal/squamous (basal) or one of the three luminal (URO, URO‐KRT5⁺, and GU) subtypes. Although uncommon in this NMIBC cohort, basal tumors (3%, n = 16) had dramatically higher grade (100%, n = 16, odds ratio [OR] = 13, relative risk = 3.25) and stage, and rapid progression to muscle invasion (median progression‐free survival = 35.4 months, p = 0.0001). URO, the most common subtype (46%, n = 220), showed rapid recurrence (median recurrence‐free survival [RFS] = 11.5 months, p = 0.039) compared to its GU counterpart (29%, n = 137, median RFS = 16.9 months), even in patients who received intravesical immunotherapy (p = 0.049). URO‐KRT5⁺ tumors (22%, n = 108) were typically low grade (66%, n = 71, OR = 3.7) and recurred slowly (median RFS = 38.7 months). Therefore, a simple immunohistochemical algorithm can identify clinically relevant molecular subtypes of NMIBC. In routine clinical practice, this three‐antibody algorithm may help clarify diagnostic dilemmas and optimize surveillance and treatment strategies for patients.

STAG2 as a prognostic biomarker in low-grade non-muscle invasive bladder cancer

OBJECTIVE

Improvements to bladder cancer risk stratification guidelines are needed to better tailor post-operative surveillance and adjuvant therapy to individual patients. We previously identified STAG2 as a commonly mutated tumor suppressor gene in bladder cancer and an independent predictor of progression in NMIBC. Here we test the value of combining STAG2 immunostaining with other risk stratification biomarkers in NMIBC, and as an individual biomarker in MIBC.

MATERIALS AND METHODS

STAG2 immunohistochemistry was performed on a progressor-enriched cohort of tumors from 297 patients with NMIBC, and on tumors from 406 patients with MIBC from Aarhus University Hospital in Denmark. Survival analysis was performed using Kaplan-Meier survival analysis, the log rank test, and Cox proportional hazards models.

RESULTS

STAG2-negative low-grade NMIBC tumors were 2.5 times less likely to progress to muscle invasion than STAG2-positive low-grade NMIBC tumors (Log-rank test, P = 0.008). In a composite group of patients with AUA intermediate and high-risk NMIBC tumors, STAG2-negative tumors were less likely to progress (Log-rank test, P = 0.02). In contrast to NMIBC, we show that STAG2 is not useful as a prognostic biomarker in MIBC.

CONCLUSIONS

STAG2 immunostaining can be used to subdivide low-grade NMIBC tumors into two groups with substantially different risks of disease progression. Furthermore, STAG2 immunostaining may be useful to enhance NMIBC risk stratification guidelines, though larger cohorts are needed to solidify this conclusion in individual risk groups. STAG2 is not useful as a biomarker in MIBC. Further study of the use of STAG2 immunostaining as a biomarker for predicting the clinical behavior in NMIBC is warranted.

The Genitourinary Pathology Society Update on Classification and Grading of Flat and Papillary Urothelial Neoplasia With New Reporting Recommendations and Approach to Lesions With Mixed and Early Patterns of Neoplasia

The Genitourinary Pathology Society (GUPS) undertook a critical review of the recent advances in bladder neoplasia with a focus on issues relevant to the practicing surgical pathologist for the understanding and effective reporting of bladder cancer, emphasizing particularly on the newly accumulated evidence post-2016 World Health Organization (WHO) classification. The work is presented in 2 manuscripts. Here, in the first, we revisit the nomenclature and classification system used for grading flat and papillary urothelial lesions centering on clinical relevance, and on dilemmas related to application in routine reporting. As patients of noninvasive bladder cancer frequently undergo cystoscopy and biopsy in their typically prolonged clinical course and for surveillance of disease, we discuss morphologies presented in these scenarios which may not have readily applicable diagnostic terms in the WHO classification. The topic of inverted patterns in urothelial neoplasia, particularly when prominent or exclusive, and beyond inverted papilloma has not been addressed formally in the WHO classification. Herein we provide a through review and suggest guidelines for when and how to report such lesions. In promulgating these GUPS recommendations, we aim to provide clarity on the clinical application of these not so uncommon diagnostically challenging situations encountered in routine practice, while also importantly advocating consistent terminology which would inform future work.

Prognostic Value of the WHO1973 and WHO2004/2016 Classification Systems for Grade in Primary Ta/T1 Non-muscle-invasive Bladder Cancer: A Multicenter European Association of Urology Non-muscle-invasive Bladder Cancer Guidelines Panel Study

BACKGROUND

In the current European Association of Urology (EAU) non-muscle-invasive bladder cancer (NMIBC) guideline, two classification systems for grade are advocated: WHO1973 and WHO2004/2016.

OBJECTIVE

To compare the prognostic value of these WHO systems.

DESIGN, SETTING, AND PARTICIPANTS

Individual patient data for 5145 primary Ta/T1 NMIBC patients from 17 centers were collected between 1990 and 2019. The median follow-up was 3.9 yr.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Univariate and multivariable analyses of WHO1973 and WHO2004/2016 stratified by center were performed for time to recurrence, progression (primary endpoint), cystectomy, and duration of survival, taking into account age, concomitant carcinoma in situ, gender, multiplicity, tumor size, initial treatment, and tumor stage. Harrell's concordance (C-index) was used for prognostic accuracy of classification systems.

RESULTS AND LIMITATIONS

The median age was 68 yr; 3292 (64%) patients had Ta tumors. Neither classification system was prognostic for recurrence. For a four-tier combination of both WHO systems, progression at 5-yr follow-up was 1.4% in low-grade (LG)/G1, 3.8% in LG/G2, 7.7% in high grade (HG)/G2, and 18.8% in HG/G3 (log-rank, p < 0.001). In multivariable analyses with WHO1973 and WHO2004/2016 as independent variables, WHO1973 was a significant prognosticator of progression (p <  0.001), whereas WHO2004/2016 was not anymore (p =  0.067). C-indices for WHO1973, WHO2004, and the WHO systems combined for progression were 0.71, 0.67, and 0.73, respectively. Prognostic analyses for cystectomy and survival showed results similar to those for progression.

CONCLUSIONS

In this large prognostic factor study, both classification systems were prognostic for progression but not for recurrence. For progression, the prognostic value of WHO1973 was higher than that of WHO 2004/2016. The four-tier combination (LG/G1, LG/G2, HG/G2, and HG/G3) of both WHO systems proved to be superior, as it divides G2 patients into two subgroups (LG and HG) with different prognoses. Hence, the current EAU-NMIBC guideline recommendation to use both WHO classification systems remains correct.

PATIENT SUMMARY

At present, two classification systems are used in parallel to grade non-muscle-invasive bladder tumors. Our data on a large number of patients showed that the older classification system (WHO1973) performed better in terms of assessing progression than the more recent (WHO2004/2016) one. Nevertheless, we conclude that the current guideline recommendation for the use of both classification systems remains correct, since this has the advantage of dividing the large group of WHO1973 G2 patients into two subgroups (low and high grade) with different prognoses.

Reappraisal of the papillary urothelial neoplasm of low malignant potential (PUNLMP)

Although the papillary urothelial neoplasm of low malignant potential (PUNLMP) diagnostic category was retained in the updated 2016 World Health Organisation (WHO) classification of tumours of the urinary system, there still exists a great deal of controversy regarding the biological behaviour of these tumours. We review PUNLMP tumours and histological grading with an emphasis on the histomorphological, genetic and clinical similarities between PUNLMP and low-grade non-invasive papillary urothelial carcinoma. A literature search using PubMed was performed. All relevant literature concerning PUNLMP and the grading of urothelial tumours was reviewed. PUNLMPs cannot be reliably distinguished from low-grade non-invasive papillary urothelial carcinomas based on the histomorphological criteria outlined in the WHO 2004/2016 classification system. PUNLMPs and low-grade non-invasive papillary urothelial carcinomas are not only morphologically similar, but also share similar molecular genetic alterations and a similar risk of recurrence and progression. In addition, there are no consensus recommendations for a different method of treatment and follow-up for these two tumour types. Attempting to distinguish PUNLMP from low-grade papillary urothelial carcinoma adds an unnecessary level of complexity to the grading and classification of urothelial tumours. We feel that PUNLMP terminology should be abandoned and that all such tumours should be classified as low-grade carcinomas until more objective determinants of clinical outcome can be established.

Automated Detection and Grading of Non-Muscle-Invasive Urothelial Cell Carcinoma of the Bladder

Accurate grading of non-muscle-invasive urothelial cell carcinoma is of major importance; however, high interobserver variability exists. A fully automated detection and grading network based on deep learning is proposed to enhance reproducibility. A total of 328 transurethral resection specimens from 232 patients were included, and a consensus reading by three specialized pathologists was used. The slides were digitized, and the urothelium was annotated by expert observers. The U-Net-based segmentation network was trained to automatically detect urothelium. This detection was used as input for the classification network. The classification network aimed to grade the tumors according to the World Health Organization grading system adopted in 2004. The automated grading was compared with the consensus and individual grading. The segmentation network resulted in an accurate detection of urothelium. The automated grading shows moderate agreement (κ = 0.48 ± 0.14 SEM) with the consensus reading. The agreement among pathologists ranges between fair (κ = 0.35 ± 0.13 SEM and κ = 0.38 ± 0.11 SEM) and moderate (κ = 0.52 ± 0.13 SEM). The automated classification correctly graded 76% of the low-grade cancers and 71% of the high-grade cancers according to the consensus reading. These results indicate that deep learning can be used for the fully automated detection and grading of urothelial cell carcinoma.

Simultaneously Quantifying Both Young's Modulus and Specific Membrane Capacitance of Bladder Cancer Cells with Different Metastatic Potential

Both Young's modulus and specific membrane capacitance (SMC) are two important physical parameters for characterizing cell status. In this paper, we utilized a thin-neck-micropipette aspiration system to simultaneously quantify Young's modulus and SMC value of six types of cell lines in different progression grades, which include four grades from the lowest metastatic potential G1 to the highest potential G4. We investigated how these two physical properties possess heterogeneities in bladder cancer cells with different grades and what roles they might play in grading bladder cancer. The characterization results of these cells of different cancer grades is linearly correlated with the cancer grades, showing that the Young's modulus is negatively linearly correlated with bladder cancer grades, while SMC shows a positive linear correlation. Furthermore, the combination of these two physical properties on a scatter diagram clearly shows the cell groups with different cancer grades, which means that this combination could be a potential tumor grading marker to identify cancer cells with different metastatic potential.

A noninvasive urine-based methylation biomarker panel to detect bladder cancer and discriminate cancer grade

BACKGROUND

Highly sensitive and specific urinary biomarkers for the early detection of bladder cancer (BC) to improve the performance of urinary cytology are needed.

OBJECTIVE

To investigate the usefulness of methylation markers in voided urine to identify BC presence and grade.

DESIGN, SETTINGS, AND PARTICIPANTS

Using genome-wide methylation strategies in Toronto, Canada and Liège, Belgium, we have identified differentially methylated genes (TWIST1, RUNX3, GATA4, NID2, and FOXE1) in low-grade vs. high-grade BC tissue and urine. We accrued urine samples from 313 patients using a 2:1 ratio in a case-control setting from Toronto, Canada, Halifax, Canada, and Zurich, Switzerland. We studied the usefulness of these 5 methylated genes to identify BC and discriminate cancer grade in voided urine specimens. Urinary cell sediment DNA was evaluated using qPCR-based MethyLight assay. Multivariable logistic regression prediction models were created.

RESULTS AND LIMITATIONS

We included 211 BC patients (180 nonmuscle invasive) and 102 controls. In univariate analyses, all methylated genes significantly predicted BC vs. no BC, and high grade vs. low grade (all P < 0.05). In multivariable analysis, NID2, TWIST1, and age were independent predictors of BC (all P < 0.05). Sensitivity of NID2 and TWIST1 to predict BC and BC grade was 76.2% and 77.6%, respectively, whereas specificity was 83.3% and 61.1%, respectively. Multivariable models predicting BC overall and discriminating between high-grade and low-grade BC reached area under the receiver operating characteristics curves of 0.89 and 0.78, respectively.

CONCLUSIONS

This multi-centric study in a real life scenario (different countries, techniques, and pathologists) supports the promise of epigenetic urinary markers in noninvasively detecting BC. With sensitivities and specificities in the range of 80%, the overall performance characteristics of this panel of methylated genes probably does not allow such signature to significantly alter clinical care at this stage but is worth further studying for instance in BC surveillance or screening in high-risk populations.

The 1973 WHO and 2004 WHO grading systems are not equal in prediction of survival among stage T1 bladder cancer patients

INTRODUCTION AND OBJECTIVES

The aim of this study was to analyse prognostic impact of tumour histological grade on survival differences between primary G2 and G3 WHO1973 stage T1 tumours which were graded as HG according to WHO2004 grading system.

MATERIALS AND METHODS

Data from 481 patients with primary T1HG bladder cancer who were treated between 1986 and 2016 in 2university centres were retrospectively reviewed. Log-rank test and Cox regression analysis was performed to compare the groups.

RESULTS

95 (19,8%) tumours were classified as G2 and 386 (80,2%) were G3. Median follow-up was 68 months. The recurrence was observed in 228 (47,5%), and progression in 109 patients (22,7%). Radical cystectomy was performed in 114 pts (23,7%) and there were 64 (13,3%) cancer specific deaths. Recurrence-free rates at 5-years follow-up for G2, G3 and all patients were 68,7%, 51,2% and 56,3% and progression-free rates were 89,3%, 73,2% and 78,1% respectively. For total observation period patients with G3 tumours presented also worse recurrence-free, and progression-free survival levels than patients with G2 tumours. In multivariate analysis, after adjustment for clinical features, the risk of recurrence and progression for G3 tumours was 1,65 and 2,42 fold higher than for G2 tumours.

CONCLUSIONS

It was shown that G3 T1 tumours are characterized by worse recurrence free and progression free survivals when compared to G2 cancers.