| Summary: | Bladder cancer is the one of the most common malignancies of the genitourinary system and the overwhelming majority of those cases, approximately 90% in the United States(1), are of the urothelial/transitional cell histologic type. Small cell histologic type of bladder cancer is extremely rare with a mean frequency of 0.7% (1), and due to its rarity, there have not been any large phase III clinical trials in order to establish a definitive treatment regimen. We report here one such case of this rare type of bladder cancer and our approach towards treatment.
A 69-year-old man had an incidental finding of microscopic hematuria during routine annual testing performed by his primary care physician. He was referred to a urologist for further evaluation, and in the interim, he began to experience symptoms of nocturia, dysuria and gross hematuria. Cystoscopy revealed a 5 cm sessile mass within the bladder and transurethral resection of the tumor was performed. Histopathological analysis of the tumor revealed muscle invasive poorly differentiated urothelial carcinoma with neuroendocrine features suggestive of small cell carcinoma. Follow-up systemic imaging only revealed multiple lesions in the liver, with the largest solitary liver lesion measuring 4.4 x 3.4 cm and no discrete lung lesions. Patient was started on palliative systemic chemotherapy with carboplatin and etoposide and follow-up imaging demonstrated excellent response after four cycles of treatment; however, follow-up imaging after the completion of 6 cycles of treatment demonstrated disease progression. Patient was referred for consideration of enrollment into any clinical trials; however, unfortunately no trials were found to be available. Patient was subsequently offered systemic treatment with single-agent immunotherapy with pembrolizumab. Due to development of left sided hydronephrosis, nephrostomy tube placement was performed and patient was also started on palliative radiation.
Primary small cell carcinoma (SCC) of the bladder is an exceedingly rare malignancy and therefore, data is not readily available in order to guide treatment decisions. The most commonly administered regimen consists of etoposide with a platinum agent, and this regimen is extrapolated from the treatment of SCC of the lung. However, as for patients like ours, who had progression of disease in a short interval and are deemed primary treatment (platinum) refractory, the prognosis certainly becomes far more grim and the treatment choices even more limited. In sharing our treatment approach, we hope to be able to provide insight towards potential future treatment choices for this most-challenging diagnosis, primary small cell carcinoma of the bladder.
(1) Blomjous CE, et. al. Small cell carcinoma of the urinary bladder. A clinicopathologic, morphometric, immunohistochemical, and ultrastructural study of 18 cases. Cancer. 1989 Sep 15; 64(6):1347-57.
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