Urothelial carcinoma, also known as transitional cell carcinoma, is a type of cancer that affects the urothelial cells lining the bladder, ureters, and renal pelvis. It is the most common type of bladder cancer and can also occur in the upper urinary tract. Urothelial carcinoma is more common in older adults and is often linked to smoking, exposure to certain chemicals, and chronic bladder inflammation. Symptoms may include blood in the urine, frequent urination, and pain during urination. Treatment options for urothelial carcinoma may include surgery, chemotherapy, and immunotherapy.