either in the glands of the bladder (adenocarcinoma) or in an embryonic remnant (urachal tumors, also adenocarcinoma). In men, adenocarcinoma occurs in the glands of the urethra near the prostate. The remaining bladder cancers are squamous cell carcinomas, which also are the most frequent type of urethral tumor in women. Tumors also develop in the pelvis of the kidney, where urine is formed, and in the ureters, the tubes that carry urine to the bladder. About 7 percent of all kidney cancers originate in the renal pelvis. The majority are transitional cell cancers, although the squamous cell type is noted more frequently in patients with a history of chronic stone problems.
There are also non-cancerous tumors called benign papillomas, labeled Ta, Grade 1 tumors. Fewer than 5 to 10 percent of patients with a benign papilloma will ever develop the more worrisome malignant
