Report From the International Society of Urological Pathology (ISUP) Consultation Conference On Molecular Pathology Of Urogenital Cancers. II. Molecular Pathology of Bladder Cancer: Progress and Challenges

Ureter mixed neuroendocrine-non-neuroendocrine neoplasm: a case report and literature review

Cases of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) of the urinary system are rare, and reports of primary MiNENs in the ureter are lacking. Herein, we present the case of a 71-year-old man who presented with painless gross hematuria and weight loss. Contrast-enhanced abdominal computed tomography (CT) revealed a tumor, comprising small cell neuroendocrine carcinoma (SCNEC) and adenocarcinomatous components, attached to the ureter. The SCNEC components were strongly positive for synaptophysin, CD56 and INSM1 and adenocarcinomatous components were strongly positive for CDX2 and cytokeratin 20, respectively. Four weeks post-surgery, the patient received four cycles of cisplatin-based chemotherapy; the 7-month follow-up CT confirmed that he was healthy without disease recurrence. The occurrence of MiNEN in the ureter with SCNEC and adenocarcinomatous components is extremely rare, wherein histopathological and immunohistochemical features aid in the diagnosis MiNEN. With its aggressive nature, MiNEN can only be effectively treated by early diagnosis and radical surgery.

Molecular Subtypes of Bladder Cancer: Component Signatures and Potential Value in Clinical Decision-making

Bladder cancer may be classified into "molecular subtypes" based on gene expression. These are associated with treatment response and patient outcomes. The gene expression signatures that define these subtypes are diverse, including signatures of epithelial differentiation, stromal involvement, cell cycle activity, and immune cell infiltration. Multiple different systems are described. While earlier studies considered molecular subtypes to be intrinsic properties of cancer, recent data have shown molecular subtypes change as tumors progress and evolve, and often differ between histologically distinct regions of a tumor. The data also indicate that some signatures that define molecular subtypes may be treated as independent continuous variables, rather than categorical subtypes, and these individual signatures may be more clinically informative. This review describes molecular subtypes of urothelial carcinoma, including histologic subtypes and tumors with divergent differentiation, and explores potential future uses in patient management.

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.

The influence of the initial clinical presentation of upper tract urothelial carcinoma on histopathological tumor features

PURPOSE

To investigate the influence of the initial clinical presentation (symptomatic vs. asymptomatic) on histopathological tumor features in patients with upper tract urothelial carcinoma (UTUC).

METHODS

We conducted a single-center, cross-sectional, and retrospective study that enrolled 72 adults with primary UTUC who underwent radical nephroureterectomy at our institution over a period of 4 years (April 2019-April 2023).

RESULTS

Symptomatic patients exhibited significantly higher frequencies of high-grade UTUC (73.6% vs. 36.8%, p = 0.006), ≥ T2 stage UTUC (60.4% vs. 26.3%, p = 0.007), and larger tumor sizes (median 5 vs. 4 cm, p = 0.015) compared to asymptomatic patients. Multiple regression analyses demonstrated significant associations between symptomatic presentation and the presence of high-grade UTUC (OR 6.35, 95% CI 1.81-22.27, p = 0.004), ≥ T2 stage UTUC (OR 5.98, 95% CI 1.62-22.08, p = 0.007), and larger tumor size (B 3.14, 95% CI 0.62-5.66, p = 0.015). A subset of patients with hematuria was separately analyzed to assess the influence of hematuria severity (gross vs. microscopic) on UTUC characteristics. Patients with gross hematuria exhibited significantly higher frequencies of high-grade UTUC (72.9% vs. 33.3%, p = 0.048) and ≥ T2 stage UTUC (58.3% vs. 22.2%, p = 0.001). Multiple regression analyses showed significant associations between gross hematuria and the presence of high-grade UTUC (OR 6.34, 95% CI 1.15-34.95, p = 0.034) and ≥ T2 stage UTUC (OR 6.54, 95% CI 1.11-38.93, p = 0.039).

CONCLUSION

Initial symptomatic presentation was independently associated with adverse histopathological UTUC characteristics, potentially attributed to earlier detection of UTUC in asymptomatic patients, before the onset of symptoms.

International Society of Urological Pathology Consensus Conference on Current Issues in Bladder Cancer. Working Group 4: Molecular Subtypes of Bladder Cancer-Principles of Classification and Emerging Clinical Utility

Molecular subtyping has been a major focus of bladder cancer research over the past decade. Despite many promising associations with clinical outcomes and treatment response, its clinical impact has yet to be defined. As part of the 2022 International Society of Urological Pathology Conference on Bladder Cancer, we reviewed the current state of the science for bladder cancer molecular subtyping. Our review included several different subtyping systems. We derived the following 7 principles, which summarize progress and challenges of molecular subtyping: (1) bladder cancer has 3 major molecular subtypes: luminal, basal-squamous, and neuroendocrine; (2) signatures of the tumor microenvironment differ greatly among bladder cancers, particularly among luminal tumors; (3) luminal bladder cancers are biologically diverse, and much of this diversity results from differences in features unrelated to the tumor microenvironment, such as FGFR3 signaling and RB1 inactivation; (4) molecular subtype of bladder cancer associates with tumor stage and histomorphology; (5) many subtyping systems include idiosyncrasies, such as subtypes recognized by no other system; (6) there are broad fuzzy borders between molecular subtypes, and cases that fall on these fuzzy borders are often classified differently by different subtyping systems; and (7) when there are histomorphologically distinct regions within a single tumor, the molecular subtypes of these regions are often discordant. We reviewed several use cases for molecular subtyping, highlighting their promise as clinical biomarkers. Finally, we conclude that data are currently insufficient to support the routine use of molecular subtyping to guide bladder cancer management, an opinion shared with the majority of conference attendees. We also conclude that molecular subtype should not be considered an "intrinsic" property of a tumor but should instead be considered the result of a specific laboratory test, performed using a specific testing platform and classification algorithm, validated for a specific clinical application.

Urothelium-Specific Expression of Mutationally Activated Pik3ca Initiates Early Lesions of Noninvasive Bladder Cancer

Although approximately 70% of bladder cancers are noninvasive and have high recurrence rates, early-stage disease is understudied. The lack of models to validate the contribution of molecular drivers of bladder tumorigenesis is a significant issue. Although mutations in PIK3CA are frequent in human bladder cancer, an in vivo model for understanding their contribution to bladder tumorigenesis is unavailable. Therefore, a Upk2-Cre/Pik3caH1047R mouse model expressing one or two R26-Pik3caH1047R alleles in a urothelium-specific manner was generated. Pik3caH1047R functionality was confirmed by quantifying Akt phosphorylation, and mice were characterized by assessing urothelial thickness, nuclear atypia, and expression of luminal and basal markers at 6 and 12 months of age. While at 6 months, Pik3caH1047R mice developed increased urothelial thickness and nuclear atypia, progressive disease was not observed at 12 months. Immunohistochemistry showed urothelium maintained luminal differentiation characterized by high forkhead box A1 (Foxa1) and peroxisome proliferator-activated receptor γ expression. Surprisingly, Pik3caH1047R mice subjected to low-dose carcinogen exposure [N-butyl-N-(4-hydroxybutyl)nitrosamine] exhibited no significant differences after exposure relative to mice without exposure. Furthermore, single-sample gene set enrichment analysis of invasive human tumors showed those with mutant PIK3CA did not exhibit significantly increased phosphatidylinositol 3-kinase/AKT pathway activity compared with wild-type PIK3CA tumors. Overall, these data suggest that Pik3caH1047R can elicit early tumorigenic changes in the urothelium, but progression to invasion may require additional genetic alterations.

The Impact of the Initial Clinical Presentation of Bladder Cancer on Histopathological and Morphological Tumor Characteristics

This study investigated the impact of the initial clinical presentation of bladder cancer on tumor characteristics. A cross-sectional, retrospective study was performed, and it involved 515 patients who underwent transurethral bladder cancer resection at the University Hospital Center Split between April 2019 and April 2023, excluding recurrent cases. The association between symptomatic versus asymptomatic presentation and bladder cancer characteristics was analyzed. A subgroup analysis compared tumor characteristics between patients with gross and microscopic hematuria. Multiple regression analyses revealed a significant association between symptomatic presentation and the detection of high-grade bladder cancer (OR 3.43, 95% CI 2.22-5.29, p < 0.001), concomitant CIS (OR 3.41, 95% CI 1.31-8.88, p = 0.012), T2 stage bladder cancer (OR 5.79, 95% CI 2.45-13.71, p < 0.001), a higher number of tumors (IRR 1.24, 95% CI 1.07-1.45, p = 0.005), and larger tumor size (B 1.68, 95% CI 1.19-2.18, p < 0.001). In the subgroup analysis, gross hematuria was associated with the detection of high-grade bladder cancer (OR 2.07, 95% CI 1.12-3.84, p = 0.020), T2 stage bladder cancer (OR 6.03, 95% CI 1.42-25.49, p = 0.015), and larger tumor size (B 1.8, 95% CI 0.99-2.6, p < 0.001). The identified associations between symptomatic presentation and unfavorable bladder cancer characteristics, likely attributed to early detection in asymptomatic cases, underscore the importance of additional research in the development of bladder cancer screening strategies.

HER2 Expression in Bladder Cancer: A Focused View on Its Diagnostic, Prognostic, and Predictive Role

Bladder cancer (BC) is a heterogeneous disease from a molecular, morphological, and clinical standpoint. HER2 is a known oncogene involved in bladder carcinogenesis. Assessing HER2 overexpression as a result of its molecular changes in a routine pathology practice using immunohistochemistry might be a useful adjunct in several scenarios, namely (1) to correctly identify flat urothelial lesions and inverted urothelial lesions in the diagnostic setting; (2) to provide prognostic hints in both non-muscle invasive (NMI) and muscle invasive (MI) tumors, thus supplementing risk stratification tools, especially when evaluating higher-risk tumors such as those with variant morphology; (3) to improve antibody panels as a surrogate marker of BC molecular subtyping. Furthermore, the potential of HER2 as a therapeutic target has been only partly explored so far, in light of the ongoing development of novel target therapies.

Receptor Tyrosine Kinase Pathway and Infiltrating Urothelial Carcinoma

Receptor tyrosine kinase pathway is frequently searched for cancer causing mutations in tumors. Emerging targeted therapies are gleam of hope for them. Infiltrating urothelial carcinoma can have many morphological aspects according to their differentiation/variants. To evaluate KRAS, BRAF, and PIK3CA mutations and HER2, EGFR, and p16 expression, we divided urothelial carcinomas into two groups: differentiated/variants (n = 12) and conventional (n = 12). We compared results with clinical, demographic, histopathologic features and survival rates. No statistically significant results could be obtained in the comparison of histopathologic properties/survival rates with mutation analysis and EGFR, HER2, and p16 status. Differentiated/variants urothelial carcinoma showed higher EGFR expression (P < 0.001). Glandular differentiation was the most frequent type, followed by squamous and sarcomatoid differentiation. We observed the most common mutation at KRAS with a propensity for urothelial carcinoma with glandular differentiation. More than one mutation/high protein expression was seen in some tumors. Targeted therapies for KRAS mutation can be effective at urothelial carcinoma with glandular differentiation. Heterologous expression of relevant proteins and genes can be a cause for targeted treatment obstacle. The determination of the molecular characters of tumors is a guide in creating targeted treatment algorithms and in choosing the patient.

Concurrent durvalumab and radiation therapy (DUART) followed by adjuvant durvalumab in patients with localized urothelial cancer of bladder: results from phase II study, BTCRC-GU15-023

BACKGROUND

Patients with bladder cancer (BC) who are cisplatin ineligible or have unresectable disease have limited treatment options. Previously, we showed targeting programmed death-ligand 1 (PD-L1) with durvalumab (durva) and radiation therapy (RT) combination was safe in BC. We now report results from a phase II study evaluating the toxicity and efficacy of durva and RT in localized BC.

METHODS

This is a single-arm, multi-institutional phase II study; N=26. Enrolled patients had pure or mixed urothelial BC (T2-4 N0-2 M0) with unresectable tumors and were unfit for surgery or cisplatin ineligible. Patients received durva concurrently with RT ×7 weeks, followed by adjuvant durva × 1 year.

PRIMARY ENDPOINTS

(A) progression-free survival (PFS) at 1 year and (B) disease control rate (DCR) post adjuvant durva. Key secondary endpoints: (A) complete response (CR) post durvaRT (8 weeks), (B) overall survival (OS), (C) PFS and (D) toxicity. Correlative studies included evaluation of baseline tumor and blood (baseline, post durvaRT) for biomarkers.

RESULTS

Median follow-up was 27 months. Evaluable patients: 24/26 post durvaRT, 22/26 for DCR post adjuvant durva, all patients for PFS and OS. Post adjuvant durva, DCR was seen in 72.7%, CR of 54.5%. 1-year PFS was 71.5%, median PFS was 21.8 months. 1-year OS was 83.8%, median OS was 30.8 months. CR at 8 weeks post durvaRT was 62.5%. Node positive (N+) patients had similar median PFS and OS. DurvaRT was well tolerated. Grade ≥3 treatment-related adverse events: anemia, high lipase/amylase, immune-nephritis, transaminitis, dyspnea (grade 4-COPD/immune), fatigue, rash, diarrhea and scleritis. No difference in outcome was observed with PD-L1 status of baseline tumor. Patients with CR/PR or SD had an increase in naïve CD4 T cells, a decrease in PD-1+CD4 T cells at baseline and an increase in cytokine-producing CD8 T cells, including interferon gamma (IFNγ) producing cells, in the peripheral blood.

CONCLUSION

Durva with RT followed by adjuvant durva was safe with promising efficacy in localized BC patients with comorbidities, including N+ patients. Larger randomized studies, like S1806 and EA8185, are needed to evaluate the efficacy of combining immunotherapy and RT in BC.

TRIAL REGISTRATION NUMBER

NCT02891161.

Immunotherapy for Bladder Cancer: Latest Advances and Ongoing Clinical Trials

For nearly 50 years, immunotherapy has been used in patients with bladder cancer in the form of Mycobacterium bovis Bacillus Calmette-Guerin (BCG), which is still the first-line therapy for non-muscle invasive disease. However, the remarkable results obtained with checkpoint inhibitor drugs, including Pembrolizumab and Atezolizumab, have fueled the quest to optimize these and other forms of immunotherapy for both non-muscle invasive as well as advanced bladder cancer. In this review we summarize the current state of the rapidly evolving field of immunotherapy in bladder cancer highlighting novel approaches and ongoing trials in this exciting area of research.

Impact of classical and basal-like molecular subtypes on overall survival in resected pancreatic cancer in the SPACIOUS-2 multicentre study

BACKGROUND

The recently identified classical and basal-like molecular subtypes of pancreatic cancer impact on overall survival (OS). However, the added value of routine subtyping in both clinical practice and randomized trials is still unclear, as most studies do not consider clinicopathological parameters. This study examined the clinical prognostic value of molecular subtyping in patients with resected pancreatic cancer.

METHODS

Subtypes were determined on fresh-frozen resected pancreatic cancer samples from three Dutch centres using the Purity Independent Subtyping of Tumours classification. Patient, treatment, and histopathological variables were compared between subtypes. The prognostic value of subtyping in (simulated) pre- and postoperative settings was assessed using Kaplan-Meier and Cox regression analyses.

RESULTS

Of 199 patients with resected pancreatic cancer, 164 (82.4 per cent) were classified as the classical and 35 (17.6 per cent) as the basal-like subtype. Patients with a basal-like subtype had worse OS (11 versus 16 months (HR 1.49, 95 per cent c.i. 1.03 to 2.15; P = 0.035)) than patients with a classical subtype. In multivariable Cox regression analysis, including only clinical variables, the basal-like subtype was a statistically significant predictor for poor OS (HR 1.61, 95 per cent c.i. 1.11 to 2.34; P = 0.013). When histopathological variables were added to this model, the prognostic value of subtyping decreased (HR 1.49, 95 per cent c.i. 1.01 to 2.19; P = 0.045).

CONCLUSION

The basal-like subtype was associated with worse OS in patients with resected pancreatic cancer. Adding molecular classification to inform on tumor biology may be used in patient stratification.

A transcriptional network of cell cycle dysregulation in noninvasive papillary urothelial carcinoma

Human cancers display a restricted set of expression profiles, despite diverse mutational drivers. This has led to the hypothesis that select sets of transcription factors act on similar target genes as an integrated network, buffering a tumor’s transcriptional state. Noninvasive papillary urothelial carcinoma (NIPUC) with higher cell cycle activity has higher risk of recurrence and progression. In this paper, we describe a transcriptional network of cell cycle dysregulation in NIPUC, which was delineated using the ARACNe algorithm applied to expression data from a new cohort (n = 81, RNA sequencing), and two previously published cohorts. The transcriptional network comprised 121 transcription factors, including the pluripotency factors SOX2 and SALL4, the sex hormone binding receptors ESR1 and PGR, and multiple homeobox factors. Of these 121 transcription factors, 65 and 56 were more active in tumors with greater and less cell cycle activity, respectively. When clustered by activity of these transcription factors, tumors divided into High Cell Cycle versus Low Cell Cycle groups. Tumors in the High Cell Cycle group demonstrated greater mutational burden and copy number instability. A putative mutational driver of cell cycle dysregulation, such as homozygous loss of CDKN2A, was found in only 50% of High Cell Cycle NIPUC, suggesting a prominent role of transcription factor activity in driving cell cycle dysregulation. Activity of the 121 transcription factors strongly associated with expression of EZH2 and other members of the PRC2 complex, suggesting regulation by this complex influences expression of the transcription factors in this network. Activity of transcription factors in this network also associated with signatures of pluripotency and epithelial-to-mesenchymal transition (EMT), suggesting they play a role in driving evolution to invasive carcinoma. Consistent with this, these transcription factors differed in activity between NIPUC and invasive urothelial carcinoma.

Immunohistochemistry subtyping of urothelial carcinoma is feasible in the daily practice

The preferred treatment of choice in muscle-invasive bladder cancer (MIBC) is usually transurethral resection followed by cystectomy, with neoadjuvant chemotherapy being a second option. As the treatment is associated with relevant side effects, a great effort is being made to improve the selection of patients, with molecular subtyping being one of the main strategies. Our aim was to develop an immunohistochemical algorithm for subtyping MIBCs. After a literature review, we have developed a simple algorithm to subtype MIBCs based on their morphology and three common antibodies: GATA3, CK5/6, and p16. We applied it to 113 muscle-invasive carcinomas. The positivity threshold for GATA3 and CK5/6 was 20% with at least moderate intensity, while p16 was 70% with moderate to intense nuclear and cytoplasmic staining. Cases GATA3 + CK5/6 - were considered luminal, while cases GATA3 - CK5/6 + were classified as nonluminal/basal squamous. Luminal p16 + cases were labeled as genomically unstable and luminal p16 - as Uro-like. Cases GATA3 + CK5/6 + with a predominantly basal pattern were labeled luminal, while diffuse cases were labeled nonluminal/basal squamous. All GATA3-CK5/6 - cases were considered nonluminal and were divided into mesenchymal-like or neuroendocrine, depending on the morphology. We were able to classify the 113 cases as: 82 (72.57%) were luminal, being 47 Uro-like (41.59%) and 35 (30.97%) genomically unstable; 31 (27.43%) were nonluminal, being 24 basal/squamous (21.24%), two (1.76%) mesenchymal-like, and five (4.42%) neuroendocrine like. We have achieved a feasible and cost-effective algorithm to subtype MIBCs from morphological features and the use of three common antibodies. Further studies in external cohorts are necessary to validate these results.

New Directions and Challenges in Targeted Therapies of Advanced Bladder Cancer: The Role of FGFR Inhibitors

Simple Summary

The aim of this study was to present and analyze the up-to-date literature describing the epidemiology, genetics, and histopathology of bladder cancer, as well as the latest methods of bladder cancer treatment. The treatment of urothelial cancer was divided depending on its stage and advancement. FGFR3 mutations and overexpression occur more frequently in bladder cancer than any other malignancy, occurring in nearly 80% of the tumors. Closer acknowledgement of targeted therapy will help physicians to navigate specific groups of patients for whom this treatment strategy can be beneficial. To that end, intense clinical research was conducted, bringing evidence for effectiveness and safety of FGFR inhibitors. Recent years of research have truly set a positive perspective for the better understanding of the complex issue of urothelial carcinoma pathology and management.

Abstract

Bladder neoplasms, including the most common urothelial carcinoma, have been an escalating problem for years, especially in highly developed countries. Recent decades have brought us a steadily growing share of this cancer in terms of both morbidity and mortality statistics. Bladder neoplasms are not only a therapeutic challenge but also an economical one due to the demanding, costly diagnostics and treatment. The treatment of urothelial cancer can be divided depending on the stage and advancement; thus, we can distinguish three main categories: non-muscle invasive bladder cancer, conventionally treated by surgical interventions; muscle invasive bladder cancer, conventionally treated with chemotherapeutics; and advanced bladder cancer with distant metastases, conventionally treated with the intensive chemotherapy in the MVAC scheme (methotrexate, vinblastine, doxorubicin, and cisplatin). Recent years have brought a breakthrough: immunotherapy and targeted therapy were discovered to be beneficial for patients disqualified from chemotherapy or patients who progressed despite treatment. This literature review summarizes the latest research into the use of targeted therapy in the treatment of advanced bladder cancer, its benefits, and its limitations.

Diagnostische und prädiktive Marker in der Harntraktzytologie

In der Routinediagnostik spielt die Mehrfach-Fluoreszenz-in-situ-Hybridisierung (FISH) nach wie vor die führende Rolle in der Abklärung unklarer Atypien in der Harntraktzytologie. Die Paris-Klassifikation (The Paris System, TPS) bildet eine wichtige Grundlage zur gezielten Indikationsstellung der FISH und untermauert die Bedeutung der morphologischen Korrelation für eine integrative Diagnosestellung. Die Next-Generation-Sequencing-Technologie, welche durch gleichzeitigen Nachweis multipler genetischer Alterationen eine hohe Sensitivität erzielt, wird in naher Zukunft auch in der Harntraktzytologie Anwendung finden.

Common Diagnostic Challenges and Pitfalls in Genitourinary Organs, With Emphasis on Immunohistochemical and Molecular Updates

CONTEXT.—

Lesions in the genitourinary (GU) organs, both benign and malignant, can demonstrate overlapping morphology, and practicing surgical pathologists should be aware of these potential pitfalls and consider a broad differential diagnosis for each specific type of lesion involving the GU organs. The following summary of the contents presented at the 6th Annual Chinese American Pathologists Association (CAPA) Diagnostic Course (October 10-11, 2020), supplemented with relevant literature review, exemplifies the common diagnostic challenges and pitfalls for mass lesions of the GU system of adults, including adrenal gland, with emphasis on immunohistochemical and molecular updates when relevant.

OBJECTIVE.—

To describe the common mass lesions in the GU system of adults, including adrenal gland, with emphasis on the diagnostic challenges and pitfalls that may arise in the pathologic assessment, and to highlight immunohistochemical workups and emerging molecular findings when relevant.

DATA SOURCES.—

The contents presented at the course and literature search comprise our data sources.

CONCLUSIONS.—

The diagnostic challenges and pitfalls that arise in the pathologic assessment of the mass lesions in the GU system of adults, including adrenal gland, are common. We summarize the contents presented at the course, supplemented with relevant literature review, and hope to provide a diagnostic framework to evaluate these lesions in routine clinical practice.

Molecular Classification of Bladder Urothelial Carcinoma Using NanoString-Based Gene Expression Analysis

Simple Summary

Our study aimed to apply a quantitative method based on mRNA counting as nCounter (NanoString Technologies, Inc). This method can obtain precise and accurate measures of RNA expression compared to RT-PCR, and which might represent an alternative to the NGS-genomic/transcriptomic profiling frequently used to generate molecular data in bladder cancer and provide clinically meaningful datasets for the molecular classification of bladder cancer. The current study generated a four-gene classifier, incorporating GATA3 and KRT20 (typically related to luminal molecular subtype) and KRT5 and KRT14 (typically related to basal molecular subtype). This methodology allowed us to explore differences in clinicopathologic parameters and potential sensitivities to ICI immunotherapy in a cohort series of 91 urothelial carcinomas of the bladder.

Abstract

Molecular classification of bladder carcinoma is a relevant topic in modern bladder cancer oncology due to its potential to improve oncological outcomes. The available molecular classifications are generally based on transcriptomic profiles, generating highly diverse categories with limited correlation. Implementation of molecular classification in practice is typically limited due to the high complexity of the required technology, the elevated costs, and the limited availability of this technology worldwide. We have conducted a gene expression analysis using a four-gene panel related to luminal and basal subtypes in a series of 91 bladder cancer cases. NanoString-based gene expression analysis using typically luminal (GATA3+/KRT20+) and basal markers (KRT14+/KRT5+/GATA3low/-/KRT20low/-) classified urothelial bladder carcinoma samples as luminal, basal, and a third category (KRT14-/KRT5-/GATA3-/KRT20-), null/double negative (non-luminal/non-basal). These three categories were meaningful in terms of overall cancer-specific survival (p < 0.0001) or when classified as conventional urothelial carcinoma and variant histology urothelial carcinoma (p < 0.0001), NMIBC vs. MIBC (p < 0.001), or by AJCC stage category Ta (p = 0.0012) and T1 (p < 0.0001) but did not reach significance in T2-T4 (p = 0.563). PD-L1 expression (low vs. high) was also different according to molecular subtype, with high PD-L1 expression mostly seen in basal and null subtypes and carcinomas with variant histology (p = 0.002). Additionally, the luminal subtype was enriched in NMIBC with favorable cancer-specific survival (p < 0.0001). In contrast, basal and null subtypes resulted in aggressive MIBC tumors with shorter cancer-specific survival (p < 0.0001), some of which presented variant histology. In conclusion, a comprehensive evaluation of a gene classifier related to molecular taxonomy using NanoString technology is feasible. Therefore, it might represent an accessible and affordable tool in this rapidly expanding area of precision genomics.

Occurrence, functionality and abundance of the TERT promoter mutations

Telomere shortening at chromosomal ends due to the constraints of the DNA replication process acts as a tumor suppressor by restricting the replicative potential in primary cells. Cancers evade that limitation primarily through the reactivation of telomerase via different mechanisms. Mutations within the promoter of the telomerase reverse transcriptase (TERT) gene represent a definite mechanism for the ribonucleic enzyme regeneration predominantly in cancers that arise from tissues with low rates of self-renewal. The promoter mutations cause a moderate increase in TERT transcription and consequent telomerase upregulation to the levels sufficient to delay replicative senescence but not prevent bulk telomere shortening and genomic instability. Since the discovery, a staggering number of studies have resolved the discrete aspects, effects and clinical relevance of the TERT promoter mutations. The promoter mutations link transcription of TERT with oncogenic pathways, associate with markers of poor outcome and define patients with reduced survivals in several cancers. In this review, we discuss the occurrence and impact of the promoter mutations and highlight the mechanism of TERT activation. We further deliberate on the foundational question of the abundance of the TERT promoter mutations and a general dearth of functional mutations within noncoding sequences, as evident from pan-cancer analysis of the whole-genomes. We posit that the favorable genomic constellation within the TERT promoter may be less than a common occurrence in other noncoding functional elements. Besides, the evolutionary constraints limit the functional fraction within the human genome, hence the lack of abundant mutations outside the coding sequences.

Telomerase reverse transcriptase (TERT) promoter mutations in primary adenocarcinoma of bladder and urothelial carcinoma with glandular differentiation: pathogenesis and diagnostic implications

Telomerase reverse transcriptase (TERT) promoter mutations have been implicated in urothelial carcinogenesis and are present in 60-80% of conventional and variants of urothelial carcinomas. We investigated the prevalence of TERT promoter mutations in 46 cases of bladder nonurachal adenocarcinoma, 30 cases of urothelial carcinoma with glandular differentiation, 24 cases of nephrogenic adenoma, eight cases of villous adenoma, 31 cases of florid cystitis glandularis, and 20 cases of intestinal metaplasia of the bladder. TERT promoter mutations were detected in 33% of adenocarcinomas of urinary bladder and in 67% of urothelial carcinomas with glandular differentiation. All 30 cases of urothelial carcinoma with glandular differentiation harbored identical TERT promoter mutation in both glandular and urothelial carcinoma components from the same tumor, suggesting a common clonal origin. TERT promoter mutations were absent in nephrogenic adenoma, villous adenoma, florid cystitis glandularis, and intestinal metaplasia of the bladder. TERT promoter mutation analysis may be a useful ancillary study in the differential diagnosis.

Primary MiNEN of the urinary bladder: an hitherto undescribed entity composed of large cell neuroendocrine carcinoma and adenocarcinoma with a distinct clinical behavior : Description of a case and review of the pertinent literature

Neuroendocrine carcinomas (NECs) of the urinary bladder are very rare and can be observed in the context of mixed neuroendocrine/non-neuroendocrine neoplasms (MiNENs), most frequently in association with urothelial carcinoma. Small cell NECs are far more common than large cell NECs (LCNECs), which are exceedingly rare. We describe a primary MiNEN of the urinary bladder, composed of a LCNEC and of an adenocarcinoma, in which the neuroendocrine component reached complete pathological regression after neoadjuvant M-VAC chemotherapy, whereas the non-neuroendocrine component of the tumor progressed to metastatic disease. Compared to mixed neuroendocrine/non-neuroendocrine neoplasms described in the literature until now, this appears to be a unique case that expands the spectrum of neuroendocrine neoplasia of the urinary bladder.

Challenging dilemmas of low grade, non-invasive bladder cancer: a narrative review

PURPOSE

To describe the current scientific knowledge and clinical experience in low-grade-non-muscle-invasive bladder cancer (LG-NMIBC) patients in challenging scenarios.

MATERIALS AND METHODS

Medline, Embase, Google Scholar, and Cochrane Central were searched until March 2021.

RESULTS

A total of 841 studies were identified, and abstracts were analyzed. Twenty-one relevant studies were then identified and reviewed. After all, information was gathered from 16 studies, the authors discussed the specific topics, and expert opinions were also included in the discussion. There have been some studies that can help us to have some insights on how to manage these patients. Very distinctive strategies have been reported in the literature, mainly anecdotally or in small randomized studies. Some of these treatments outlined in the present manuscript include repeated TURBTs, chemoablation, BCG immunoablation, partial cystectomy, radical cystectomy, radiotherapy, chemotherapy, and future perspectives. In the current manuscript, we have combined these strategies in a proposed algorithm.

CONCLUSION

For those LG-NMIBC patients in challenging scenarios, we have found repeated TURBTs, chemoablation, BCG immunoablation, partial cystectomy, radical cystectomy, radiotherapy, and chemotherapy are attractive modalities to treat them effectively. Also, the current manuscript proposes an algorithm to overcome these challenges.

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.

Molecular pathology of urothelial carcinoma

The current personalized oncology era has witnessed significant efforts to integrate clinical, pathological, and molecular classifications. The growing need for molecular biomarkers to feed personalized oncology, together with the unprecedented wealth of knowledge on the molecular basis of bladder cancer, has led to a novel approach to this disease, incorporating molecularly generated data in clinical practice for locally advanced or metastatic disease. Translational research allows a better understanding of the early events in the development of urothelial carcinoma in the urinary bladder. Thus, mutations in the KMT2D and KDM6A chromatin-modifying genes confer competitive advantages that drive cells to colonize larger regions of the urothelium. Additional mutations in TP53, PIK3CA, FGFR3, or RB1 genes then trigger the process of malignant transformation in the urothelium. In the current review, we provide an overview of what could be the expected transition from the morphology-based classification to a combined, molecularly enriched reporting of clinically meaningful parameters aiming to promote personalized oncology of urothelial carcinoma.

[Molecular pathology of urogenital tumors : Recommendations from the 2019 International Society of Urological Pathology (ISUP) Consensus Conference]

Das zunehmende Verständnis molekularer Grundlagen von Tumoren sowie der Fortschritt in der Diversifizierung der onkologischen Therapien versprechen individualisierte Therapieoptionen, welche bislang jedoch nur ansatzweise in die Therapieplanung von urologischen Tumoren eingegangen sind. Daher hat die Internationale Gesellschaft für Urologische Pathologie (ISUP) im März 2019 eine Konsenskonferenz zur Erarbeitung evidenzbasierter Handlungsempfehlungen zur molekularpathologischen Diagnostik beim Urothelkarzinom, Nierenzellkarzinom, Prostatakarzinom, Peniskarzinom und testikulären Keimzelltumoren durchgeführt. Die auf dieser Konsenskonferenz erarbeiteten Empfehlungen sind kürzlich in 5 separaten Manuskripten veröffentlich worden und werden in der vorliegenden Arbeit zusammengefasst.

Im Rahmen der Konferenzvorbereitung wurde eine umfassende Umfrage zur derzeitigen Praxis molekularer Testungen bei urogenitalen Tumoren unter den Mitgliedern der ISUP durchgeführt. Auf der Konferenz wurden die Ergebnisse und die entsprechenden Hintergrundinformationen durch 5 Arbeitsgruppen präsentiert und Handlungsempfehlungen für die Diagnostik erarbeitet. Eine Übereinstimmung von 66 % der Konferenzteilnehmer wurde als Konsens definiert.

Stage T1 bladder cancer: diagnostic criteria and pitfalls

Accurate pathological staging is crucial for patient management. Patients with T1 bladder cancer are at risk of recurrence, progression, and death of cancer. Recognition of early invasion (stage T1 disease) in urothelial carcinoma remains one of the most challenging areas in urological surgical pathology practice. A logical roadmap to T1 diagnosis would include careful evaluation of histological grade, stromal epithelial interface, characteristics of the invading epithelium, and the stroma associated responses. Tangential sectioning, crush and cautery artifacts, and associated inflammatory infiltrate are commonly encountered problems and the source of pitfalls. In this review, we outline diagnostic criteria, common pitfalls, and different histological patterns of invasion into the lamina propria. Current recommendations on reporting of biopsy and transurethral resection specimens, molecular biomarkers, clinical implications of T1 cancer diagnosis and recent developments on the T1 substaging are also discussed. Most T1 bladder cancer patients will benefit from conservative management after restaging transurethral resection of bladder and bacillus Calmette-Guérin maintenance. Patients with high risk features, such as concurrent urothelial carcinoma in situ, increased depth of invasion, lymphovascular invasion, and variant histology among others, should be considered for early cystectomy.

The International Society of Urological Pathology Consultation on Molecular Pathology of Urogenital Cancer

The 2019 Consultation Conference on the molecular pathology of urogenital cancers was organized by the International Society of Urological Pathology (ISUP) to have an understanding of the current use of molecular-genetic markers and to make recommendations on their application in prostate, bladder, renal, testicular, and penile cancer. This brief introductory article describes the organization of this conference and provides its rationale and main findings.

Urothelial carcinoma: variant histology, molecular subtyping, and immunophenotyping significant for treatment outcomes

Although urothelial carcinoma (UC) has been recognised as a homogenous disease entity until recently, it exhibits widely diverse histological variants. Recent studies have revealed that some histological variants may serve as markers of very high risk for advanced cancers and poor prognoses. Certain histological variants can generate a pathological T stage, which may result in unnecessary surgery. Though platinum based chemotherapy is the standard treatment, the use of immune checkpoint inhibitors (ICIs) for UC treatment has become a major trend in oncology. UCs showing specific histological variants have responded exceptionally well to chemotherapy and ICIs. Currently, molecular studies base molecular classification on gene expression profile signatures in order to make diagnoses or predict responses to chemotherapies and ICIs. Notably, some histological variants correlate with specific molecular subtypes. The usefulness of immunophenotyping for classification purposes was recognised only recently. Immunophenotypes are classified into three categories according to lymphocyte distribution in or around the cancer cell nest: desert, excluded, and inflamed. This immunophenotyping has been increasingly shown to be of value in predicting the response to ICIs. This review describes the morphological characteristics of histological variants as well as the advantages and limitations in determining them, with particular reference to clinical benefits. Subsequently, we describe the concept of molecular classification and immunophenotypes, and their morphological features, which are easily interpreted and amenable to daily practice via hematoxylin and eosin staining. We also consider the clinical advantages, limitations, and issues encountered while using these in routine clinical practice.