Stage T1 bladder cancer: diagnostic criteria and pitfalls

International Society of Urological Pathology (ISUP) Consensus Conference on Current Issues in Bladder Cancer: Working Group 3: Subcategorization of T1 Bladder Cancer

Emerging data on T1 bladder cancer subcategorization (aka substaging) suggests a correlation with oncological outcomes. The International Society of Urological Pathology (ISUP) organized the 2022 consensus conference in Basel, Switzerland to focus on current issues in bladder cancer and tasked working group 3 to make recommendations for T1 subcategorization in transurethral bladder resections. For this purpose, the ISUP developed and circulated a survey to their membership querying approaches to T1 bladder cancer subcategorization. In particular, clinical relevance, pathological reporting, and endorsement of T1 subcategorization in the daily practice of pathology were surveyed. Of the respondents of the premeeting survey, about 40% do not routinely report T1 subcategory. We reviewed literature on bladder T1 subcategorization, and screened selected articles for clinical performance and practicality of T1 subcategorization methods. Published literature offered evidence of the clinical rationale for T1 subcategorization and at the conference consensus (83% of conference attendants) was obtained to report routinely T1 subcategorization of transurethral resections. Semiquantitative T1 subcategorization was favored (37%) over histoanatomic methods (4%). This is in line with literature findings on practicality and prognostic impact, that is, a shift of publications from histoanatomic to semiquantitative methods or by reports incorporating both methodologies is apparent over the last decade. However, 59% of participants had no preference for either methodology. They would add a comment in the report briefly stating applied method, interpretation criteria (including cutoff), and potential limitations. When queried on the terminology of T1 subcategorization, 34% and 20% of participants were in favor of T1 (microinvasive) versus T1 (extensive) or T1 (focal) versus T1 (nonfocal), respectively.

Micro-mechanical fingerprints of the rat bladder change in actinic cystitis and tumor presence

Tissue mechanics determines tissue homeostasis, disease development and progression. Bladder strongly relies on its mechanical properties to perform its physiological function, but these are poorly unveiled under normal and pathological conditions. Here we characterize the mechanical fingerprints at the micro-scale level of the three tissue layers which compose the healthy bladder wall, and identify modifications associated with the onset and progression of pathological conditions (i.e., actinic cystitis and bladder cancer). We use two indentation-based instruments (an Atomic Force Microscope and a nanoindenter) and compare the micromechanical maps with a comprehensive histological analysis. We find that the healthy bladder wall is a mechanically inhomogeneous tissue, with a gradient of increasing stiffness from the urothelium to the lamina propria, which gradually decreases when reaching the muscle outer layer. Stiffening in fibrotic tissues correlate with increased deposition of dense extracellular matrix in the lamina propria. An increase in tissue compliance is observed before the onset and invasion of the tumor. By providing high resolution micromechanical investigation of each tissue layer of the bladder, we depict the intrinsic mechanical heterogeneity of the layers of a healthy bladder as compared with the mechanical properties alterations associated with either actinic cystitis or bladder tumor.

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.

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.

Survival Outcome of Partial Cystectomy versus Transurethral Bladder Tumor Resection in T1 High-Grade Bladder Cancer Patients: A Propensity Score Matching Study

PURPOSE

Partial cystectomy was investigated as a method of bladder preservation with better disease outcomes than transurethral bladder tumor resection in T1 high-grade bladder cancer patients. Method and materials. The national Surveillance, Epidemiology, and End Results database (SEER) (2004-2015) were used to obtain patients diagnosed with T1 high-grade bladder cancer, and finally, 25263 patients were enrolled in our study. The Kaplan-Meier method with the log-rank test was performed to analyze the outcome of overall survival (OS) and cancer-specific survival (CSS) between patients undergoing partial cystectomy (PC), transurethral resection of bladder tumor (TURBT), or radical cystectomy (RC). Moreover, the propensity score matching (PSM) and multivariable Cox proportional hazard model were also utilized in the study.

RESULTS

Ultimately, 24635 patients were undergoing TURBT, while 190 and 438 patients were, respectively, assigned to the PC and RC groups. Compared with patients with TURBT, a tendency of a higher proportion of higher older and male patients was observed in the PC group. When matching with RC patients, patients in the PC group were commonly older and had bigger tumor sizes and single tumors (All P < 0.05). After 1 : 1 PSM, 190 patients with TURBT and 160 patients receiving PC were selected. In survival analysis, the patients in the PC group had a higher survival probability of both OS and CSS before and after PSM compared with those in the TURBT group. Meanwhile, no significant differences were observed between the RC and PC groups in OS and CSS analysis. Moreover, multivariable Cox regression showed that PC was a protective factor for overall mortality (ACM) and cancer-specific mortality (CSM) compared with TURBT in T1 high-grade patients (All P < 0.05).

CONCLUSION

Patients undergoing partial cystectomy were shown to have a better outcome compared with those with transurethral bladder tumor resection in T1 high-grade bladder cancer patients. Partial cystectomy could be the more worthwhile choice for bladder preservation in T1 high-grade bladder cancer patients.

Intermediate-risk Non-muscle-invasive Bladder Cancer: Updated Consensus Definition and Management Recommendations from the International Bladder Cancer Group

CONTEXT

Intermediate-risk (IR) non-muscle-invasive bladder cancer (NMIBC) is a heterogeneous disease.

OBJECTIVE

To update the International Bladder Cancer Group (IBCG) guidance and provide practical recommendations on IR NMIBC management.

EVIDENCE ACQUISITION

A collaborative review of published randomized clinical trials, meta-analyses, systematic reviews, and clinical practice guidance on IR NMIBC published before January 2022 was undertaken using PubMed/Medline.

EVIDENCE SYNTHESIS

Variation exists between guidelines in defining IR NMIBC. The IBCG recommends defining IR NMIBC as any TaLG tumor that is either recurrent or multifocal or has size ≥3 cm, OR any T1LG tumor. If the 3 tier grading system is used, than any TaG2 tumor would also be considered IR diease regardless of whether new diagnosis or recurrent. Accurate grading and staging of tumor, particularly in ruling out HG/G3 disease and/or carcinoma in situ, are crucial. The IBCG recommends that management of IR NMIBC should be further based on the following risk factors: multifocal tumor (more than one), early recurrence (<1 yr), frequent recurrence (>1/yr), tumor size (≥3 cm), and failure of prior intravesical treatment. Patients with no risk factors are best managed by one dose of postoperative intravesical chemotherapy. Patients with one to two risk factors should be offered additional adjuvant induction intravesical chemotherapy (or bacillus Calmette-Guérin (BCG) if prior chemotherapy has been used). Patients with three or more risk factors should be offered induction plus 1-yr maintenance BCG. Where BCG is not available or recurrent disease following BCG is present, alternative intravesical treatments such as chemotherapy (single agent, combination, or chemohyperthermia) or a clinical trial are recommended.

CONCLUSIONS

Standardizing the definition of IR NMIBC is critical for appropriate management of patients and for allowing a comparison of outcomes across clinical trials. The IBCG recommends defining IR NMIBC as any TaLG tumor that is either recurrent or multifocal or  ≥3 cm, OR any T1LG tumor. If the 3 tier grading system is used, than any TaG2 tumor would also be considered IR disease regardless of whether new diagnosis or recurrent.  Adjunctive management should then be based on established risk factors.

PATIENT SUMMARY

Standardizing the definition of intermediate-risk (IR) non-muscle-invasive bladder cancer (NMIBC), which is a heterogeneous disease, is critical for appropriate management of patients. The International Bladder Cancer Group recommends classification of IR NMIBC tumors and personalized management based on the following risk factors: multifocal tumor (more than one), early recurrence (<1 yr), frequent recurrence (>1/yr), tumor size (≥3 cm), and previous intravesical treatment.

Bladder Cancer Sample Handling and Reporting: Pathologist's Point of View

The aim of this narrative review is to provide adequate information on handling and reporting of the bladder cancer samples to improve the closely collaboration between pathologists and urologists. The main (but not exclusive) research tool used was PubMed and 87 references were selected and quoted in the text. We have considered handling of biopsies, transurethral resection (TUR), and cystectomy specimens to summarize the different methods of sampling and the related issues. Moreover, we considered and discussed the main prognostic factors, such as histological tumor type, grade, and stage of bladder cancer, that should be described in the pathological report. In addition, critical issues encountered in the interpretation of histological samples were discussed.

Distinctive morphological and molecular features of urothelial carcinoma with an inverted growth pattern

Urothelial carcinoma with an inverted growth pattern (UC-IGP) is a peculiar entity within the spectrum of urothelial lesions. While efforts have been made over the last few decades to unravel its carcinogenesis and relationship with conventional urothelial carcinoma, the exact classification of inverted urothelial lesions is a matter of debate. The morphological features of UC-IGP pose several issues in differential diagnosis with other mostly benign lesions. Various techniques, including immunohistochemistry, UroVysion, and many molecular methods, have been employed to study the exact nature of this lesion. The aim of this review is to provide a comprehensive overview of the morphological and immunophenotypical aspects of UC-IGP. Moreover, we present and discuss the immunohistochemical and molecular markers involved in diagnosis and prognosis of UC-IGP lesions.