Are There Different Types Of Bladder Cancer?

Yes. There are two broad types of cancers in the bladder: primary and metastatic. Primary bladder cancers are those that begin in the bladder itself. Metastatic cancers are those that originated in another organ and then spread to the bladder. Other tumors can get into the bladder through the bloodstream, through the lymphatic system, or by directly extending from a nearby organ, such as the prostate or the cervix.

Cancers originating in the bladder are far more common than cancers that spread to the bladder from another location. There are several types of primary tumors. Recall that transitional cell cancer accounts for at least 90% of all bladder cancers. Transitional cell tumors can be classified as (1) papillary, (2) sessile, or (3) a mix of both types. Papillary tumors look like a piece of cauliflower attached to the wall by a short stalk; sessile tumors look flat and are broad-based. Almost 70% of transitional cell tumors are papillary types, which tend to have a better prognosis than sessile tumors. Less common types of bladder cancer include squamous cell cancer, adenocarcinoma, and urachal carcinoma.

Squamous cell carcinoma accounts for 3% to 7% of bladder cancers in the United States; however, in Egypt it accounts for 75% of the bladder cancers. There is a parasitic infection called  schistosomiasis that is very common in Egypt. Infection with this parasite strongly predisposes a person to the development of squamous cell cancer. The parasite burrows into the wall of the bladder, which chronically irritates the bladder. Over many years, this chronic irritation can lead to the development of bladder cancer, most often squamous cell cancer. Other conditions that cause chronic irritation also predispose to this type of tumor.

Chronic indwelling catheters, for example, can irritate the bladder and pre-dispose someone to this tumor. Squamous cell carcinoma does not tend to spread to the lymph nodes like transitional cell cancer does, although it does tend to spread aggressively directly through the bladder into neighboring structures. Because it is so locally aggressive and relatively resistant to chemotherapy or radiation, it usually has a worse prognosis than transitional cell cancers.

Adenocarcinoma of the bladder is quite uncommon, accounting for approximately 2% of all bladder cancers in the United States. These tumors are also associated with chronic irritation. They tend to be high-grade aggressive tumors and are therefore usually associated with a worse prognosis. Urachal carcinoma is a specific type of adenocarcinoma of the bladder, but it is unique in that it does not originate in the lining of the bladder. These develop from the outer surface of the bladder, extending toward the inside of the bladder. They can then metastasize to the lymph nodes, the liver, lung, and bone.