1. ¹Department of Medicine, Indiana University, Indianapolis, IN, USA
2. ²Department of Pathology, Northwestern University, Chicago, IL, USA
3. ³Department of Pathology, Cordoba University, Cordoba, Spain
4. ⁴Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
5. ⁵Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN, USA
6. ⁶Department of Urology, Indiana University, Indianapolis, IN, USA
7. ⁷Department of Biostatistics, Yale University, New Haven, CT, USA
8. ⁸Department of Pathology, University of Chicago, Chicago, IL, USA

Correspondence: Dr L Cheng, MD, Department of Pathology and Laboratory Medicine, Indiana University Medical Center, University Hospital 3465, 550 North University Blvd., Indianapolis, IN 46202, USA. E-mail: lcheng@iupui.edu

Received 25 February 2004; Revised 4 May 2004; Accepted 4 May 2004; Published online 15 October 2004.

Abstract

The prognosis for small cell carcinoma of the urinary bladder is poor, and strategies for improved therapy are needed. Targeted therapy against the c-kit proto-oncogene has been successful in the management of gastrointestinal stromal tumor. We investigated the expression of c-kit in 52 cases of small cell carcinoma of the urinary bladder. Specimens with more than 10% of cells demonstrating strong membrane staining were considered to have positive immunostaining for c-kit. c-kit expression was detected in 21 of 52 specimens from these patients. Among the 21 specimens, seven had less than 10% staining, and were considered to be negative. Nine had 11–50% staining, and five had more than 50% staining. Overall, 14 of 52 (27%) small cell carcinomas of the urinary bladder were positive for c-kit expression. During a median follow-up of 11 months, 60% of the patients died of bladder cancer. No association was found between c-kit expression and survival or other clinicopathologic parameters. Five-year cancer-specific survivals for c-kit-positive and c-kit-negative tumors were 9 and 15%, respectively (P=0.36). A significant proportion (27%) of small cell carcinomas of the urinary bladder expressed c-kit, suggesting that it may prove useful as a therapeutic target in small cell carcinoma of the urinary bladder.