Incidence and Characterization of Pure Non-Urothelial Cancers: A 10-Year Review

Background Bladder cancer is the sixth most common malignancy in the United States. Urothelial carcinoma makes up 90% of bladder cancer histology, which may be pure or mixed. It includes adenocarcinoma (Ad), squamous (SqC), glandular, sarcomatoid (St), micropapillary, small cell (SC) and plasmacytoid variants. Pure non-urothelial cancers have a worse overall survival when compared to urothelial cancer with mixed histologic features. However, little research has been done to characterize pure non-urothelial histologies, and there are no randomized clinical trials evaluating treatment modalities for non-urothelial cancers. This retrospective study characterizes pure non-urothelial cancers and their treatments. Methods A retrospective chart review of the last 10 years was performed using data from the George Washington University Cancer Center Tumor Registry Data. Statistical analysis was performed using the Fisher’s test and Kaplan-Meier survival curves. Results Out of 449 consecutive patients with bladder cancers, 19 patients had pure non-urothelial carcinoma (4.2%): 7 SqC, 6 Ad, 3 SC, 2 lymphoma (Ly), and 1 St. SqC and Ad were more likely than SC to be diagnosed at an advanced stage (p=0.04), with median age of diagnosis at 53.5 years for Ad, 68 years for SC and 69 years for Sq. None of the SC metastasized. Primary treatment for 94% of patients was a surgical intervention (9 TURBT, 2 partial cystectomy, 2 radical cystectomy, and 2 nephroureterectomy); 1 received neoadjuvant therapy. 11 patients received adjuvant chemotherapy – 7 with gemcitabine-based regimens and 10 with platinumbased regimens. While not statistically significant, median overall survival varied – 404 days for Ad, 213 days for SqC, and 1567 days for SC. Conclusions SC was a more favorable histology when compared to SqC or Ad, presenting at an earlier stage with lower incidence of metastasis that perhaps reflected the improved overall survival. Identifying patients with more aggressive disease earlier allows for the potential role for more aggressive therapies that may result in improved outcomes. While the sample size is small, it identifies characteristics and potential differences between bladder cancer with rare histologies