En-bloc resection of bladder tumors for pathological staging: the value of lateral margins analysis

What's new in WHO fifth edition - urinary tract

The fifth edition of the WHO Blue Book on urological tumours, specifically in the bladder chapter, represents a refinement and update in the classification of bladder tumours building on the aggregate major changes made in previous editions. Progress in the molecular underpinnings of urothelial tumours, particularly with promising stratifiers for more precision-based treatment approaches, have been made. Special attention has been paid to burning questions in bladder pathology, such as grading, heterogeneous lesions, inverted tumours and substaging. The concept of neuroendocrine tumours will be explained precisely.

[Interpretation of biopsy material after transuretral and laser en bloc resection of non-muscle-invasive bladder cancer]

Bladder cancer is one of the most common onco-urological diseases, ranked second in frequency among all tumors of the urinary system after prostate cancer. At the time of detection of the primary tumor, approximately 75% of patients have no invasion into the muscularis layer (non-muscle-invasive carcinoma), with tumor growth limited to the basal membrane (stage Ta) or submucosal base (stage T1). Removal of the tumor in a «unified block» (laser en-bloc resection or L-ERBT), unlike routine transurethral resection, allows to obtain qualitative biopsy material for precise pathomorphological staging of the tumor process. In order to accurately stratify a patient into one or another risk group, verification of the following morphological parameters is required: degree of tumor differentiation and its malignancy, depth of invasion, foci of carcinoma in situ at resection margins, presence or absence of lymphovascular invasion. Identification of tumor variant histology is also recommended. Information on presence or absence of detrusor elements in the specimen is necessary in the morphological report, as this parameter is considered as a criterion of radically performed tumor removal. According to ICCR recommendations (International Collaboration on cancer reporting), it is recommended to use subclassification of T1 stage using all possible criteria: volume and/or depth of invasion (assessed in mm), and/or width of invasion «spot» (assessed in mm), and/or involvement of anatomical structure - muscularis mucosae. Full morphological examination of the material obtained during the primary resection of the tumor is an important step in the diagnosis and treatment of bladder cancer, as it allows to stratify the patient into one or another risk group and, accordingly, allows to develop a personalized postoperative management.

Immune checkpoint inhibitors for BCG-resistant NMIBC: the dawn of a new era

INTRODUCTION

High risk non-muscle invasive bladder cancer (NMIBC) is a recurring and potentially lethal disease. To date, with the exception of radical surgery, there are no validated strategies for patients not responding to intravesical BCG therapy. Immune checkpoint inhibitors (ICI) are currently being tested for BCG-resistant NMIBC. We report current available data and ongoing trials exploring the efficacy and safety of ICI in this setting.

EVIDENCE ACQUISITION

A narrative search was performed including the combination of the following words: ("immunotherapy") AND ("BCG" AND "resistant" OR "non-muscle AND invasive") AND ("bladder AND "cancer"). Three search engines: PubMed, Embase and Web of Science were queried up to November 1, 2020. Congress abstracts reporting results and not only trials' design were also referenced. The US National Library of Medicine was queried via clinicaltrials.gov to explore ongoing trials on the subject.

EVIDENCE SYNTHESIS

Pembrolizumab demonstrated a promising 40.6% (95% CI: 30.7-51.1) complete response within the KEYNOTE-057, with a median duration of response of 16.2 months. Preliminary data in the phase II SWOG S1605 trial with atezolizumab showed a 41.1% complete response at 3 months. Avelumab is being tested in the PREVERT phase II study exploring ICI with radiotherapy (60-66 Gy) of the whole bladder. CheckMate 9UT analyzes nivolumab monotherapy versus nivolumab + BMS-986205 (IDO-1 inhibitor) with or without BCG in patients with BCG-unresponsive, carcinoma in situ with or without papillary component. Finally, durvalumab is being studied in the BCG resistant space with radiotherapy in the ADAPT-BLADDER study. After proving its safety profile in the phase 1, the trial will randomize patients to durvalumab + BCG, durvalumab + radiation therapy (6Gy 3×) or BCG rechallenge.

CONCLUSIONS

Pembrolizumab has received FDA approval in the treatment of BCG-resistant NMIBC. All five other ICI molecules are currently being extensively tested within clinical trials. The results of the currently ongoing studies are awaited with impatience by the uro-oncologic community and will probably open a new era in the treatment of BCG-resistant NMIBC.