Papillary urothelial neoplasm of low malignant potential (PUN-LMP): Still a meaningful histo-pathological grade category for Ta, noninvasive bladder tumors in 2019?

NMGrad: Advancing Histopathological Bladder Cancer Grading with Weakly Supervised Deep Learning

The most prevalent form of bladder cancer is urothelial carcinoma, characterized by a high recurrence rate and substantial lifetime treatment costs for patients. Grading is a prime factor for patient risk stratification, although it suffers from inconsistencies and variations among pathologists. Moreover, absence of annotations in medical imaging renders it difficult to train deep learning models. To address these challenges, we introduce a pipeline designed for bladder cancer grading using histological slides. First, it extracts urothelium tissue tiles at different magnification levels, employing a convolutional neural network for processing for feature extraction. Then, it engages in the slide-level prediction process. It employs a nested multiple-instance learning approach with attention to predict the grade. To distinguish different levels of malignancy within specific regions of the slide, we include the origins of the tiles in our analysis. The attention scores at region level are shown to correlate with verified high-grade regions, giving some explainability to the model. Clinical evaluations demonstrate that our model consistently outperforms previous state-of-the-art methods, achieving an F1 score of 0.85.

International Society of Urological Pathology Consensus Conference on Current Issues in Bladder Cancer: Main Conclusions and Recommendations

The 2022 International Society of Urological Pathology consensus conference on current issues in bladder cancer made recommendations regarding adoption of a three-tier grading system, grading of cancers with grade heterogeneity, grading and reporting of bladder cancers with subtype/divergent differentiation, and mandatory subcategorisation of T1 bladder cancers.

Validation of non-muscle-invasive bladder cancer risk stratification updated in the 2021 European Association of Urology guidelines

Objective

The objective of this study is to validate the predictive ability of the 2021 European Association of Urology (EAU) risk model compared to that of existing risk models, including the 2019 EAU model and risk scoring tables of the European Organization for Research and Treatment of Cancer, Club Urologico Espanol de Tratamiento Oncologico, and Japanese Nishinihon Uro-oncology Extensive Collaboration Group.

Patients and methods

This retrospective multi-institutional database study included two cohorts-3024 patients receiving intravesical bacillus Calmette-Guerin (BCG) treatment (BCG cohort) and 789 patients not receiving BCG treatment (non-BCG cohort). The Kaplan-Meier estimate and log-rank test were used to visualize and compare oncological survival outcomes after transurethral surgery among the risk groups. Harrell's concordance index (C-index) was used to evaluate the predictive ability of the models.

Results

We observed a risk shift from the 2019 EAU risk grouping to the 2021 EAU risk grouping in a substantial number of patients. For progression, the C-index of the 2021 EAU model was significantly higher than that of the 2019 EAU model in both the BCG (0.617 vs. 0.572; P = 0.011) and non-BCG (0.718 vs. 0.560; P < 0.001) cohorts. According to the 2021 EAU model, 731 (24%) and 130 (16%) patients in the BCG and non-BCG cohorts, respectively, were considered to have a very high risk. Survival analysis showed no significant differences among the five very high-risk subgroups in both cohorts. A major limitation was potential selection bias owing to the retrospective nature of this study.

Conclusions

The updated 2021 EAU model showed better stratification than the three existing risk models, especially for progression, in both cohorts, determining the most appropriate postoperative treatment and identifying patients requiring intensified surveillance or early cystectomy.

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.

Recent Advances in the Classification of Bladder Cancer - Updates from the 5th Edition of the World Health Organization Classification of the Urinary and Male Genital Tumors

BACKGROUND

The World Health Organization Classification (WHO) of Urinary and Male Genital Tumors has recently been updated to its 5th edition. The new edition presents a comprehensive approach to the classification of urinary and male genital tumors with an incorporation of morphologic, clinical, and genomic data.

OBJECTIVE

This review aims to update the new classification of bladder cancer in the 5th edition and to highlight important changes in nomenclatures, diagnostic criteria, and molecular characterization, as compared to the 4th edition.

METHODS

The pathologic classification of bladder cancer in the 5th edition of WHO Classification of Urinary and Male Genital Tumours was compared to that in the 4th edition. PubMed was searched using key words, including bladder cancer, WHO 1973, WHO 1998, WHO 2004, WHO 2016, histology, pathology, genomics, and molecular classification in the time frame from 1973 to August of 2022. Other relevant papers were also consulted, resulting in the selection of 81 papers as references.

RESULTS

The binary grading of papillary urothelial carcinoma (UC) is practical, but it may be oversimplified and contribute to "grade migration" in recent years. An arbitrary cutoff (5%) has been proposed for bladder cancers with mixed grades. The diagnosis of papillary urothelial neoplasm with low malignant potential has been dramatically reduced in recent years because of overlapping morphology and treatment with low-grade papillary UC. An inverted growth pattern should be distinguished from true (or destructive) stromal invasion in papillary UC. Several methods have been proposed for pT1 tumor substaging, but it is often challenging to substage pT1 tumors in small biopsy specimens. Bladder UC shows a high tendency for divergent differentiation, leading to several distinct histologic subtypes associated with an aggressive clinical behavior. Molecular classification based on the genomic analysis may be a useful tool in the stratification of patients for optimal treatment.

CONCLUSIONS

The 5th edition of WHO Classification of Urinary and Male Genital Tumours has made several significant changes in the classification of bladder cancer. It is important to be aware of these changes and to incorporate them into routine clinical practice.

Precursors of urinary bladder cancer: molecular alterations and biomarkers

Clinical surveillance and follow-up of patients diagnosed with or at risk for urinary bladder cancers represent long-term, invasive, and costly processes for which supplemental biomarker information could help provide objective, personalized risk assessment. In particular, there are several precursors and possible precursors to urinary bladder cancer for which clinical behavior is heterogenous and interobserver variability in histopathologic diagnosis make it difficult to standardize management. This review seeks to highlight these precursor lesions from a diagnostic perspective (including flat urothelial lesions, papillary urothelial lesions, squamous lesions, and glandular lesions) and qualify known multiomic biomarkers that may help explain their behavior, predict patient risk, and acknowledge the nuance inherent to the question of whether these lesions are "benign" or "preneoplastic."

Evaluation of grade and invasiveness of bladder urothelial carcinoma using infrared imaging and machine learning

Urothelial bladder carcinoma (BC) is primarily diagnosed with a subjective examination of biopsies by histopathologists, but accurate diagnosis remains time-consuming and of low diagnostic accuracy, especially for low grade non-invasive BC. We propose a novel approach for high-throughput BC evaluation by combining infrared (IR) microscopy of bladder sections with machine learning (partial least squares-discriminant analysis) to provide an automated prediction of the presence of cancer, invasiveness and grade. Cystoscopic biopsies from 50 patients with clinical suspicion of BC were histologically examined to assign grades and stages. Adjacent tissue cross-sections were IR imaged to provide hyperspectral datasets and cluster analysis segregated IR images to extract the average spectra of epithelial and subepithelial tissues. Discriminant models, which were validated using repeated random sampling double cross-validation, showed sensitivities (AUROC) ca. 85% (0.85) for the identification of cancer in epithelium and subepithelium. The diagnosis of non-invasive and invasive cases showed sensitivity values around 80% (0.84-0.85) and 76% (0.73-0.80), respectively, while the identification of low and high grade BC showed higher sensitivity values 87-88% (0.91-0.92). Finally, models for the discrimination between cancers with different invasiveness and grades showed more modest AUROC values (0.67-0.72). This proves the high potential of IR imaging in the development of ancillary platforms to screen bladder biopsies.

T1G1 Bladder Cancer: Prognosis for this Rare Pathological Diagnosis Within the Non-muscle-invasive Bladder Cancer Spectrum

BACKGROUND

The pathological existence and clinical consequence of stage T1 grade 1 (T1G1) bladder cancer are the subject of debate. Even though the diagnosis of T1G1 is controversial, several reports have consistently found a prevalence of 2-6% G1 in their T1 series. However, it remains unclear if T1G1 carcinomas have added value as a separate category to predict prognosis within the non-muscle-invasive bladder cancer (NMIBC) spectrum.

OBJECTIVE

To evaluate the prognostic value of T1G1 carcinomas compared to TaG1 and T1G2 carcinomas within the NMIBC spectrum.

DESIGN, SETTING, AND PARTICIPANTS

Individual patient data for 5170 primary Ta and T1 bladder tumors from 17 hospitals in Europe and Canada were analyzed. Transurethral resection (TUR) was performed between 1990 and 2018.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Time to recurrence and progression were analyzed using cumulative incidence functions, log-rank tests, and multivariable Cox regression models stratified by institution.

RESULTS AND LIMITATIONS

T1G1 represented 1.9% (99/5170) of all carcinomas and 5.3% (99/1859) of T1 carcinomas. According to primary TUR dates, the proportion of T1G1 varied between 0.9% and 3.5% per year, with similar percentages in the early and later calendar years. We found no difference in time to recurrence between T1G1 and TaG1 (p = 0.91) or between T1G1 and T1G2 (p = 0.30). Time to progression significantly differed between TaG1 and T1G1 (p < 0.001) but not between T1G1 and T1G2 (p = 0.30). Multivariable analyses for recurrence and progression showed similar results.

CONCLUSIONS

The relative prevalence of T1G1 diagnosis was low and remained constant over the past three decades. Time to recurrence of T1G1 NMIBC was comparable to that for other stage/grade NMIBC combinations. Time to progression of T1G1 NMIBC was comparable to that for T1G2 but not for TaG1, suggesting that treatment and surveillance of T1G1 carcinomas should be more like the approaches for T1G2 NMIBC in accordance with the intermediate and/or high risk categories of the European Association of Urology NMIBC guidelines.

PATIENT SUMMARY

Although rare, stage T1 grade 1 (T1G1) bladder cancer is still diagnosed in daily clinical practice. Using individual patient data from 17 centers in Europe and Canada, we found that time to progression of T1G1 cancer was comparable to that for T1G2 but not TaG1 cancer. Therefore, our results suggest that primary T1G1 bladder cancers should be managed with more aggressive treatment and more frequent follow-up than for low-risk bladder cancer.

French AFU Cancer Committee Guidelines - Update 2022-2024: Non-muscle-invasive bladder cancer (NMIBC)

OBJECTIVE

To update the ccAFU recommendations for the management of bladder tumours that do not infiltrate the bladder muscle (NBMIC).

METHODS

A systematic review (Medline) of the literature from 2020 to 2022 was performed, taking account of the diagnosis, treatment options and surveillance of NMIBC, while evaluating the references with their levels of evidence.

RESULTS

The diagnosis of NMIBC (Ta, T1, CIS) is made after complete full-thickness tumour resection. The use of bladder fluorescence and the indication of a second look (4-6 weeks) help to improve the initial diagnosis. The EORTC score is used to assess the risk of recurrence and/or tumour progression. Through the stratification of patients in low, intermediate and high-risk categories, adjuvant treatment can be proposed: intravesical chemotherapy (immediate postoperative, initiation regimen) or BCG (initiation and maintenance regimen) instillations, or even the indication of cystectomy for BCG-resistant patients.

CONCLUSION

Updating the ccAFU recommendations should contribute to improving patient management, as well as the diagnosis and treatment of NMIBC.

[Early cystectomy-patient selection and technique]

Early radical cystectomy (RC) is a therapeutic option for non-muscle invasive bladder cancer (NMIBC). The 15-year overall survival after early RC in NMIBC patients is about 70%. Nevertheless, RC is associated with significant morbidity and mortality and therefore requires careful patient selection. The aim of the following review is to assess the selection process for early RC in NMIBC. Especially, the new European Association of Urology (EAU) risk calculator identifying NMIBC patients with very high risk for disease progression is described in detail. Furthermore, the technical aspects of the procedure are evaluated. A review of the current literature (PubMed) and national and international guideline recommendations was also conducted.

Bladder cancer recurrence in papillary urothelial neoplasm of low malignant potential (PUNLMP) compared to G1 WHO 1999: a population-based study

OBJECTIVE

Papillary urothelial neoplasm of low malignant potential (PUNLMP) and stage TaG1 non-muscle invasive bladder cancer (NMIBC) represent separate categories in current WHO 1999 grade definitions. Similarly, PUNLMP and Ta low-grade are separate entities in the WHO 2004/2016 grading system. However, this classification is currently questioned by reports showing a similar risk of recurrence and progression for both categories.

PATIENTS AND METHODS

In this population-based study, risk estimates were evaluated in patients diagnosed with PUNLMP (n = 135) or stage TaG1 (n = 2176) NMIBC 2004-2008 with 5-year follow-up registration in the nation-wide Bladder Cancer Data Base Sweden (BladderBaSe). The risk of recurrence was assessed using multivariable Cox regression with adjustment for multiple confounders (age, gender, marital status, comorbidity, educational level, and health care region).

RESULTS

At five years, 28/135 (21%) patients with PUNLMP and 922/2176 (42%) with TaG1 had local recurrence. The corresponding progression rates were 0.7% (1/135) and 4.0% (86/2176), respectively. A higher relative risk of recurrence was detected in patients with TaG1 tumours compared to PUNLMP (Hazard Ratio 1.6, 95% CI 1.2-2.0) at 5-year follow-up, while progression events were too few to compare.

CONCLUSIONS

The difference in risk of recurrence between primary stage TaG1 and PUNLMP stands in contrast to the recently adapted notion that treatment and follow-up strategies can be merged into one low-risk group of NMIBC.

Recent Advances in the Management of Patients with Non-Muscle-Invasive Bladder Cancer Using a Multidisciplinary Approach: Practical Recommendations from the Spanish Oncology Genitourinary (SOGUG) Working Group

Simple Summary

This report presents clinically relevant advances in the management of non-muscle-invasive bladder cancer, which have been the focus of discussion of expert members of the Spanish Oncology Genitourinary (SOGUG) Multidisciplinary Working Group in the framework of the Genitourinary Alliance project (12GU), designed as a space for the integration of novel information in the care of bladder cancer patients. The present study is focused on different aspects regarding the evaluation of hematuria, assessment of second (or repeated) transurethral resection of bladder cancer, histopathological diagnosis and problems with tumor grading, importance of histological variants, shortage of drug supply, and the current role and influence of immunotherapy and biological markers on the oncological outcome of patients. All proposals and recommendations have a multidisciplinary practical approach and are intended to help clinicians in shared decision making for patients with non-muscle-invasive urothelial cancer.

Abstract

On the basis of the discussion of the current state of research on relevant topics of non-muscle-invasive bladder cancer (NMIBC) among a group of experts of the Spanish Oncology Genitourinary (SOGUG) Working Group, recommendations were proposed to overcome the challenges posed by the management of NMIBC in clinical practice. A unified definition of the term ‘microhematuria’ and the profile of the patient at risk are needed. Establishing a ‘hematuria clinic’ would contribute to a centralized and more efficient evaluation of patients with this clinical sign. Second or repeated transurethral resection (re-TUR) needs to be defined, including the time window after the first procedure within which re-TUR should be performed. Complete tumor resection is mandatory when feasible, with specification of the presence or absence of muscle. Budding should be used as a classification system, and stratification of T1 tumors especially in extensive and deep tumors, is advisable. The percentage of the high-grade component should always be reported, and, in multiple tumors, grades should be reported separately. Luminal and basal subtypes can be identified because of possibly different clinical outcomes. Molecular subtypes and immunotherapy are incorporated in the management of muscle-invasive bladder cancer but data on NMIBC are still preliminary.

European Association of Urology Guidelines on Non-muscle-invasive Bladder Cancer (Ta, T1, and Carcinoma in Situ)

CONTEXT

The European Association of Urology (EAU) has released an updated version of the guidelines on non-muscle-invasive bladder cancer (NMIBC).

OBJECTIVE

To present the 2021 EAU guidelines on NMIBC.

EVIDENCE ACQUISITION

A broad and comprehensive scoping exercise covering all areas of the NMIBC guidelines since the 2020 version was performed. Databases covered by the search included Medline, EMBASE, and the Cochrane Libraries. Previous guidelines were updated, and the level of evidence and grade of recommendation were assigned.

EVIDENCE SYNTHESIS

Tumours staged as Ta, T1 and carcinoma in situ (CIS) are grouped under the heading of NMIBC. Diagnosis depends on cystoscopy and histological evaluation of tissue obtained via transurethral resection of the bladder (TURB) for papillary tumours or via multiple bladder biopsies for CIS. For papillary lesions, a complete TURB is essential for the patient's prognosis and correct diagnosis. In cases for which the initial resection is incomplete, there is no muscle in the specimen, or a T1 tumour is detected, a second TURB should be performed within 2-6 wk. The risk of progression may be estimated for individual patients using the 2021 EAU scoring model. On the basis of their individual risk of progression, patients are stratified as having low, intermediate, high, or very high risk, which is pivotal to recommending adjuvant treatment. For patients with tumours presumed to be at low risk and for small papillary recurrences detected more than 1 yr after a previous TURB, one immediate chemotherapy instillation is recommended. Patients with an intermediate-risk tumour should receive 1 yr of full-dose intravesical bacillus Calmette-Guérin (BCG) immunotherapy or instillations of chemotherapy for a maximum of 1 yr. For patients with high-risk tumours, full-dose intravesical BCG for 1-3 yr is indicated. For patients at very high risk of tumour progression, immediate radical cystectomy should be considered. Cystectomy is also recommended for BCG-unresponsive tumours. The extended version of the guidelines is available on the EAU website at https://uroweb.org/guideline/non-muscle-invasive-bladder-cancer/.

CONCLUSIONS

These abridged EAU guidelines present updated information on the diagnosis and treatment of NMIBC for incorporation into clinical practice.

PATIENT SUMMARY

The European Association of Urology has released updated guidelines on the classification, risk factors, diagnosis, prognostic factors, and treatment of non-muscle-invasive bladder cancer. The recommendations are based on the literature up to 2020, with emphasis on the highest level of evidence. Classification of patients as having low, intermediate, or and high risk is essential in deciding on suitable treatment. Surgical removal of the bladder should be considered for tumours that do not respond to bacillus Calmette-Guérin (BCG) treatment and tumours with the highest risk of progression.

European Association of Urology (EAU) Prognostic Factor Risk Groups for Non-muscle-invasive Bladder Cancer (NMIBC) Incorporating the WHO 2004/2016 and WHO 1973 Classification Systems for Grade: An Update from the EAU NMIBC Guidelines Panel

BACKGROUND

The European Association of Urology (EAU) prognostic factor risk groups for non-muscle-invasive bladder cancer (NMIBC) are used to provide recommendations for patient treatment after transurethral resection of bladder tumor (TURBT). They do not, however, take into account the widely used World Health Organization (WHO) 2004/2016 grading classification and are based on patients treated in the 1980s.

OBJECTIVE

To update EAU prognostic factor risk groups using the WHO 1973 and 2004/2016 grading classifications and identify patients with the lowest and highest probabilities of progression.

DESIGN, SETTING, AND PARTICIPANTS

Individual patient data for primary NMIBC patients were collected from the institutions of the members of the EAU NMIBC guidelines panel.

INTERVENTION

Patients underwent TURBT followed by intravesical instillations at the physician's discretion.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Multivariable Cox proportional-hazards regression models were fitted to the primary endpoint, the time to progression to muscle-invasive disease or distant metastases. Patients were divided into four risk groups: low-, intermediate-, high-, and a new, very high-risk group. The probabilities of progression were estimated using Kaplan-Meier curves.

RESULTS AND LIMITATIONS

A total of 3401 patients treated with TURBT ± intravesical chemotherapy were included. From the multivariable analyses, tumor stage, WHO 1973/2004-2016 grade, concomitant carcinoma in situ, number of tumors, tumor size, and age were used to form four risk groups for which the probability of progression at 5 yr varied from <1% to >40%. Limitations include the retrospective collection of data and the lack of central pathology review.

CONCLUSIONS

This study provides updated EAU prognostic factor risk groups that can be used to inform patient treatment and follow-up. Incorporating the WHO 2004/2016 and 1973 grading classifications, a new, very high-risk group has been identified for which urologists should be prompt to assess and adapt their therapeutic strategy when necessary.

PATIENT SUMMARY

The newly updated European Association of Urology prognostic factor risk groups for non-muscle-invasive bladder cancer provide an improved basis for recommending a patient's treatment and follow-up schedule.

International Society of Urological Pathology Expert Opinion on Grading of Urothelial Carcinoma

CONTEXT

Grading is the mainstay for treatment decisions for patients with non-muscle-invasive bladder cancer (NMIBC).

OBJECTIVE

To determine the requirements for an optimal grading system for NMIBC via expert opinion.

EVIDENCE ACQUISITION

A multidisciplinary working group established by the International Society of Urological Pathology reviewed available clinical, histopathological, and molecular evidence for an optimal grading system for bladder cancer.

EVIDENCE SYNTHESIS

Bladder cancer grading is a continuum and five different grading systems based on historical grounds could be envisaged. Splitting of the World Health Organization (WHO) 2004 low-grade class for NMIBC lacks diagnostic reproducibility and molecular-genetic support, while showing little difference in progression rate. Subdividing the clinically heterogeneous WHO 2004 high-grade class for NMIBC into intermediate and high risk categories using the WHO 1973 grading is supported by both clinical and molecular-genetic findings. Grading criteria for the WHO 1973 scheme were detailed on the basis of literature findings and expert opinion.

CONCLUSIONS

Splitting of the WHO 2004 high-grade category into WHO 1973 grade 2 and 3 subsets is recommended. Provision of more detailed histological criteria for the WHO 1973 grading might facilitate the general acceptance of a hybrid four-tiered grading system or-as a preferred option-a more reproducible three-tiered system distinguishing low-, intermediate (high)-, and high-grade NMIBC.

PATIENT SUMMARY

Improvement of the current systems for grading bladder cancer may result in better informed treatment decisions for patients with bladder cancer.

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.

The performance of the Xpert Bladder Cancer Monitor Test and voided urinary cytology in the follow-up of urinary bladder tumors

BACKGROUND

Cystoscopy in complement with urinary cytology represents the gold standard for the follow-up of patients with urinary bladder tumours. Xpert Bladder Cancer Monitor Test (XBC) is a novel mRNA-based urine test for bladder cancer surveillance. The aim of the study was to evaluate the performance of the XBC and voided urinary cytology (VUC) in the follow-up of bladder tumours.

PATIENTS AND METHODS

The XBC was performed on stabilized voided urine and VUC was performed on urine samples. The results were compared to cystoscopic findings and histopathological results after transurethral resection of the bladder lesion.

RESULTS

For the prediction of malignant histopathological result sensitivity, the specificity and negative predictive value were 76.9%, 9 7.5% and 93.0% for the XBC and 38.4%, 9 7.5% and 83.3%, respectively for VUC. For the prediction of suspicious or positive cystoscopic finding sensitivity, the specificity and negative predictive value were 75.0%, 95.2%, and 93.0% respectively for the XBC and 41.7%, 97.6%, and 85.4% for VUC. The sensitivities for papilary urothelial neoplasms of low malignant potential (PUNLMP), low- and high-grade tumours were 0.0%, 66.7% an d 100.0% for the XBC and 0.0%, 66 .7% and 42.9%, respectively for VUC.

CONCLUSIONS

The XBC showed significantly higher overall sensitivity and negative predictive value than VUC and could be used to increase the recommended follow-up cystoscopy time intervals. Complementing the XBC and voided urinary cytology does not improve performance in comparison to the XBC alone.

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.