Do amount of variant differentiation and mitotic rate in bladder cancer change with neoadjuvant chemotherapy?

Overview of histologic variants of urothelial carcinoma: current trends and narrative review on treatment outcomes

Background and Objective

The histologic variants of urothelial carcinoma (UC) are tumors arising from within the urothelium in which some component of the tumor morphology is other than urothelial. They are underdiagnosed, aggressive and have varying pathologic response rates to systemic chemotherapy. There are no consensus guidelines on the use of systemic chemotherapy in variant histology (VH) of UC. We performed a contemporary review on pathologic response rates to neoadjuvant systemic therapy and survival outcomes following radical cystectomy in order to provide a rationale for clinical practice recommendations on the management of UC with VH.

Methods

A PubMed literature search was conducted for all English articles from inception reporting either pathological response rates to neoadjuvant treatment or survival outcomes after radical cystectomy in non-metastatic VH of UC.

Key Content and Findings

Neoadjuvant chemotherapy (NAC) prior to radical cystectomy was shown to be a beneficial treatment strategy in UC with VH. The micropapillary, plasmacytoid, nested and sarcomatoid histologic variants were associated with worse survival outcomes compared to conventional UC and UC with squamous or glandular differentiation despite initial downstaging with chemotherapy. There is evidence of improved survival in patients with sarcomatoid differentiation receiving NAC compared to RC alone. The major prognostic factors that affect survival outcomes in VH of UC include histologic variant subtype, patient age, presence of lymphovascular invasion, hydronephrosis, nodal metastasis and advanced T stage at diagnosis. Recent studies demonstrate that VH of UC are heterogenous tumors and responsiveness to NAC may be a function of the molecular subtypes present.

Conclusions

Based on these findings, NAC to achieve pathologic downstaging prior to radical cystectomy is recommended for MIBC with VH. Biomarkers identified by molecular profiling with immunohistochemistry will need to be validated as predictors of response to NAC in future trials.

Forty years of cisplatin-based chemotherapy in muscle-invasive bladder cancer: are we understanding how, who and when?

PURPOSE

For 40 years cisplatin-based chemotherapy has been administered to patients with muscle-invasive bladder cancer (MIBC). The best evidence of its efficacy is found in the context of neoadjuvant chemotherapy (NAC). However, the benefit to the patient is modest, with an improvement in 5-year overall survival of only 5-8%. Approximately 60% of patients still have muscle-invasive disease at cystectomy despite NAC. Selecting patients based on the likelihood of response appears to be a promising strategy to improve on this modest benefit. To realize this promise, researchers are investigating biomarkers for identifying responders and non-responders prior to NAC.

METHODS

In this review, we discuss a number of tissue- and liquid-based biomarkers associated with the response to NAC.

RESULTS AND CONCLUSIONS

We elaborate biomarkers at the methylation, DNA, RNA and protein levels and give their current status in clinical trials and/or their implementation in daily clinical practice. In particular, detection of alterations in DNA damage repair pathways as well as molecular subtypes seems to be a promising method for identifying responders to NAC. Furthermore, we illustrate liquid-based biomarkers. Circulating tumor DNA (ctDNA) in patient blood and urine appear to offer an elegant way for biological characterization of MIBC. Recent data show that the presence of ctDNA is limited in patients with localized MIBC being considered for NAC. At this disease stage, ctDNA in patient urine may be more promising for the genomic characterization of MIBC. However, ctDNA in blood or urine has not yet been rigorously investigated in this clinical context.