In the last decade, the various entities of bladder cancer have been recognized more, and the awareness has increased among pathologists and clinicians. Variability among pathologist is still an issue but is gradually improving. The issue of tumor heterogeneity is also important, and we still don’t know what percentage of VH and non-urothelial cancer is significant. Lastly, we have learned that the quality of the first initial TURBT procedure is extremely important to acquire the maximum histological data.
In the Netherlands, between 1995 and 2006, 7.7% of 28000 bladder cancer patients had VH. However, according to Dr. Witjes, the true rate of VH is probably higher, around 10-20%. In non-muscle invasive bladder cancer (NMIBC) it is known that some VH, such as micropapillary, plasmacytoid, nested, sarcomatoid, microcystic, squamous and adenocarcinoma, have a worse prognosis. According to the most recent EAU guidelines, there is a strong recommendation that the pathological report specifies the presence of VH. This usually puts the NMIBC in the highest risk category, affecting the available treatment options for these patients. The EAU guidelines recommend immediate radical cystectomy to NMIBC patients with VH, except those with squamous differentiation and glandular differentiation. When comparing upfront radical cystectomy to BCG therapy, there is a significant 5-year disease-specific survival difference in favor of radical cystectomy (Figure 1).
Figure 1 – Disease-specific survival in clinical T1 patients with variant histology bladder cancer:
In patients with muscle-invasive bladder cancer (MIBC) the clinical stage, the margin status, nodal status, presence of lymphovascular invasion and CIS, all have a significant prognostic effect. The morphological subtypes (including VH) also have a profound impact. In MIBC patients, VH has a similar complete response, overall survival, disease survival, and salvage cystectomy rates as in “standard” urothelial carcinoma. The treatment for MIBC patients with VH should be radical cystectomy, and some reports do state that the prognosis is worse for these patients than for patients with “standard” urothelial carcinoma. Neoadjuvant chemotherapy is only useful in patients with small cell cancer, and in patients with urothelial cancer with squamous or glandular differentiation.
Dr. Witjes concluded his talk with a few words on the future. According to him, we will be able to incorporate the molecular characterization of bladder tumors with histology data, to see which tumors respond better to different treatments. For instance, it has been shown that small cell bladder cancer with basal molecular subtype responds better to chemotherapy than other VH types.
Presented by: F. Witjes, Nijmegen, The Netherlands
Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Twitter:@GoldbergHanan at the EAU Robotic Urology Section (ERUS) Meeting - September 5 - 7, 2018 - Marseille, France
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