Clinical and therapeutic significance of aberrant differentiation patterns in bladder cancer

Non-Muscle Invasive Bladder Cancer with Variant Histology: Biological Features and Clinical Implications

BACKGROUND

The most common bladder cancer (BC) histotype is pure urothelial carcinoma (UC), which may undergo divergent differentiation in some cases. Variant histology (VH) presents along variable morphologies, either single or combined between them or with pure UC. From a clinical standpoint, the vast majority of BC is diagnosed at non-invasive or minimally invasive stages, namely as non-muscle invasive BC (NMIBC). There is a wide range of therapeutic options for patients with NMIBC, according to their clinical and pathological features. However, current risk stratification models do not show optimal effectiveness. Evidence from the literature suggests that VH has peculiar biological features, and may be associated with poorer survival outcomes compared to pure UC.

SUMMARY

In order to describe the biological features and prognostic/predictive role of VH in NMIBC, and to discuss current treatment options, we performed a systematic literature search through multiple databases (PubMed/Medline, Google Scholar) for relevant articles according to the following terms, single and/or in combination: "non-muscle invasive bladder cancer," "variant histology," "micropapillary variant," "glandular differentiation," "squamous differentiation," "nested variant," "plasmacytoid variant," and "sarcomatoid variant." We extracted 99 studies including original articles, reviews, and systematic reviews, and subsequently analyzed data from 16 studies reporting on the outcome of NMIBC with VH. We found that the relative rarity of these forms as well as the heterogeneity in study populations and therapeutic protocols results in conflicting findings overall. Key Messages: The presence of VH should be taken into account when counseling a patient with NMIBC, since it may upgrade the disease to high-risk tumor and thus warrant a more aggressive treatment.

Role of Neoadjuvant Chemotherapy in Squamous Variant Histology in Urothelial Bladder Cancer: Does Presence and Percentage Matter?

BACKGROUND

The purpose of this study was to evaluate the effect of neoadjuvant chemotherapy (NACT) on squamous variant (SV) bladder cancer by investigating patients presenting with SV histology at the time of transurethral resection (TUR), stratified by their receipt of NACT.

MATERIALS AND METHODS

The records of 71 patients with muscle-invasive bladder cancer and SV in the TUR specimen who underwent cystectomy between 2008 and 2018 were reviewed. Our primary outcome was pathologic response at time of cystectomy. Secondary outcomes included recurrence-free survival and overall survival stratified by receipt of NACT. A subgroup analysis was then conducted on the patients with defined SV% on TUR stratified by % involvement (< 50% SV vs. ≥ 50% SV).

RESULTS

The median age of the NACT and no-NACT groups was 60.2 and 70 years, respectively (P = .003). The complete response rate at cystectomy was 60% versus 13.7% for the NACT and no-NACT groups, respectively (P < .001). The non-organ-confined disease rate at time of radical cystectomy was 35% for the NACT group and 68.6% for the no-NACT group (P = .01). The NACT group had fewer recurrences than the no-NACT group (10% vs 47.1%; P = .003). In the subgroup analysis, the lower rate of non-organ-confined disease persisted for the patients who underwent NACT at the lower SV percentage but failed to remain significant at greater percentage involvement. This was also true for overall survival.

CONCLUSIONS

The effect of NACT in variant histology bladder cancer is variable. In patients with SV, these results favor the recommendation in favor of NACT administration, particularly when the primary tumor has < 50% involvement by the variant histology.

Squamous Differentiation Predicts Poor Response to Cisplatin-Based Chemotherapy and Unfavorable Prognosis in Urothelial Carcinoma of the Urinary Bladder

OBJECTIVE

The efficacy of chemotherapy on UCSD is not known. This study was conducted to investigate the efficacy of cisplatin-based chemotherapy and prognosis of patients with UC with or without SD of the bladder.

METHODS

Patients with invasive bladder cancer (clinical T3-4aN0M0) who were treated between March 2003 and March 2015 with 2 or 3 cycles of neoadjuvant chemotherapy followed by radical cystectomy were retrospectively evaluated. Treatment outcomes were compared for each pathologic type in UCSD and pure UC. The primary end point was pathologic response in the cystectomy specimens. Disease-free survival and overall survival were secondary end points.

RESULTS

We evaluated 9 patients with UCSD and 29 patients with pure UC. In the cystectomy specimens, pathologic complete response without residual tumors was not seen in any patients with UCSD, but evident in 10 patients (34.5%) with pure UC. The proportion of pathologic downstaging was significantly lower in patients with UCSD than in those with pure UC (11.1% vs. 51.7%; P = .031). Patients with UCSD had poorer disease-free survival (P < .001) and overall survival (P = .001) than those with pure UC. On multivariate Cox regression analysis, SD in UC was an independent predictor of recurrence (hazard ratio, 4.43; 95% confidence interval, 1.44-13.6, P = .009) and mortality (hazard ratio, 3.51; 95% confidence interval, 1.11-11.1, P = .032).

CONCLUSIONS

UCSD of the bladder is less sensitive to cisplatin-based chemotherapy and has poor prognosis.

Bladder preserving approach for liposarcomatoid variant of transitional urothelial carcinoma

Urothelial carcinoma of the bladder with variant histologies is usually underdiagnosed and understaged. It is found in <25% of cases during transurethral resection of bladder tumours. The majority of cases carry a worse prognosis, with higher rates of recurrence and progression, and should be managed aggressively. Here, we report a rare case of liposarcomatoid variant of urothelial carcinoma managed by partial cystectomy and standard pelvic lymph node dissection.

Sarcomatoid variant of urothelial carcinoma (carcinosarcoma, spindle cell carcinoma): a review of the literature

Background. Sarcomatoid variant of urothelial carcinoma (SVUC) was added to the WHO classification in 2004. Aims. To review the literature. Materials and Method. Various internet databases were used. Result. SVUCs are rare biphasic malignant neoplasms exhibiting morphologic/immunohistochemical evidence of epithelial and mesenchymal differentiation with the presence or absence of heterologous elements. Some cases of SVUC have been associated with radiation therapy and cyclophosphamide treatment. Patients' ages range from 50 to 77 years (mean age 66). Patients tend to be younger and they more commonly presented with high-grade histology and advanced stage disease, in comparison with patients who had conventional urothelial carcinoma (CUC). Results of molecular/genetic studies strongly argue for a common monoclonal cell origin of both the epithelial and mesenchymal components in SUVC. The cancer specific survival of SVUC is poor in comparison with CUC. Radical surgical excision and chemoradiation may be associated with improved prognosis; chemoradiation as an organ preserving alternative to radical excision may be associated with improved outcome. There is no consensus opinion on the best treatment modalities for SUVC. Conclusions. SVUC is rare and is associated with inferior outcome compared with CUC. A multicentre trial of various treatment options is required. Cases of SVUC should be reported.

[Non-invasive and invasive urothelial tumours: special challenges in uropathological diagnostics]

The current 2004 WHO classification of bladder tumors categorizes non-invasive and invasive urothelial neoplasms into prognostically relevant groups according to the histopathological cell morphology and underlying genetic changes. Although many parts of the classification have not been changed dramatically, even small changes have caused uncertainty and scepticism among urologists and pathologists in recent years. The following review article is structured into various challenges for urologists and pathologists and provides an overview of rare but clinically relevant subgroups and diagnostics, interpretation of diagnoses and pathological findings with respect to consequences for the daily clinical routine (extended diagnosis, therapy and prognosis).

Comparative outcomes of pure squamous cell carcinoma and urothelial carcinoma with squamous differentiation in patients treated with radical cystectomy

PURPOSE

We compared clinical outcomes, and identified predictors of cancer specific and overall survival after radical cystectomy in patients with urothelial carcinoma with squamous differentiation and those with pure squamous cell carcinoma.

MATERIALS AND METHODS

We reviewed data on 2,031 patients treated with radical cystectomy and pelvic lymph node dissection at a single high volume referral center. Of these patients 78 had squamous cell carcinoma and 67 had squamous differentiation. Survival estimates by histological subtype were described using Kaplan-Meier methods. Within histological subtypes pathological stage, nodal invasion, soft tissue margins, age and gender were evaluated as predictors of cancer specific survival and overall survival using univariate Cox regression.

RESULTS

Median followup was 44 months. Of 104 patient deaths 60 died of their disease. We did not find a statistically significant difference between survival curves of patients with squamous cell carcinoma and squamous differentiation (log rank overall survival p = 0.6, cancer specific survival p = 0.17). Positive soft tissue margins were associated with worse cancer specific survival (HR 6.92, 95% CI 2.98-16.10, p ≤0.0005) and overall survival (HR 3.68, 95% CI 1.84-7.35, p ≤0.0005) in patients with pure squamous cell carcinoma. Among patients with squamous differentiation, pelvic lymphadenopathy was associated with decreased overall survival (HR 2.52, 95% CI 1.33-4.77, p = 0.004) and cancer specific survival (HR 3.23, 95% CI 1.57-6.67, p = 0.002).

CONCLUSIONS

There appears to be no evidence of a difference in cancer specific survival or overall survival between patients with squamous cell carcinoma and those with squamous differentiation treated with radical cystectomy and pelvic lymph node dissection. Patients with squamous differentiation and tumor metastases to pelvic lymph nodes should be followed more closely, and adjuvant treatment should be considered to improve survival. Wide surgical resection is critical to achieve local tumor control and improve survival in patients with squamous cell carcinoma.

Histologic variants of urothelial bladder cancer and nonurothelial histology in bladder cancer

Bladder cancer can be classified histologically as urothelial or non-urothelial. Urothelial cancer has a propensity for divergent differentiation, which has increasingly been recognized in recent years due to heightened awareness and improved immunohistochemistry techniques. Furthermore, the recent World Health Organization classification of urothelial cancers improved clarity on this issue, with its listing of 13 histologic variants of urothelial cancer. The divergent differentiation patterns include, amongst others, squamous, glandular, micropapillary, nested, lymphepithelioma-like, plasmacytoid and sarcomatoid variants of urothelial cancer. Attempts to quantify the amount of divergent differentiation present, such as using the nonconventional differentiation number, have been made recently, which will improve the ability to compare publications from different centres. Genetic-based studies have indicated that the histologic variants of urothelial cancer arise from a common clonal precursor. Mostly, the current evidence suggests that urothelial cancer with divergent differentiation has a worse prognosis when compared with pure urothelial cancer. This article will review the current literature on variant histologies of urothelial cancer, and well as new developments in pure squamous cell carcinoma, small cell carcinoma and adenocarcinoma of the bladder.