Broadly speaking, bladder cancer mainly includes two types: primary cancer and metastatic cancer. Primary bladder cancer originates from the bladder itself, while metastatic cancer originates from other organs, except that the cancer cells spread to the bladder, usually through the bloodstream, lymphatic system, or directly from neighboring organs to the bladder, such as the prostate, rectum, and cervix.
Primary bladder cancer is much more common than metastatic bladder cancer. The most common of these is uroepithelial cancer, which accounts for more than 90% of cases. Bladder cancer can have various forms: 1) papillary, which looks like cauliflower or watercress with a thin tip attached to the bladder wall; 2) flat, which looks like a flake or strip, velvety, with a reddish surface and no tip attached to the bladder wall; 3) solid, which looks like a wart-like superfluous organism, lumpy, with a wide base and a wide tip attached to the bladder wall. About 70% of uroepithelial carcinomas are papillary and it has a better prognosis than broad-based and non-tipped tumors.
Less common bladder cancers include squamous cell carcinoma, adenocarcinoma, and carcinoma of the umbilical canal. Squamous cell carcinoma accounts for approximately 3-7% of bladder cancers; in Egypt, it accounts for 75% of all bladder cancers. A parasitic infection called schistosomiasis is common in Egypt, and infection with this parasite creates a chronic irritation in the bladder that predisposes the patient to squamous cell carcinoma after several years. Other conditions that can cause chronic irritation in the bladder, such as prolonged catheterization, can also predispose patients to squamous cell carcinoma. Squamous cell carcinoma does not metastasize to lymph nodes as much as uroepithelial carcinoma, but it can spread directly and penetrate the bladder to reach adjacent organs. Squamous cell carcinoma is more locally invasive and insensitive to radiotherapy, so it has a worse prognosis than urothelial carcinoma. Adenocarcinoma of the bladder is very rare, accounting for approximately 2% of all bladder cancers. This tumor is also associated with chronic irritation, is highly invasive, and has an even worse prognosis. Umbilical ureteral carcinoma is a specific type of bladder adenocarcinoma that originates in the outer layer of the bladder and invades the inner layer of the bladder due to a different origin than the bladder uroepithelium. It can metastasize to organs such as lymph nodes, liver, lungs and bones.