The bladder is the organ that stores the urine delivered from the kidneys via a tube called the ureter. A layer of muscle surrounds the bladder, which squeezes during urination to empty the bladder. According to the Merck Manuals, an online medical library, more than 67,000 new cases of bladder cancer are diagnosed each year in the United States. Bladder cancer is more common in men, who get bladder cancer three times more often than women. There are three common types of bladder cancer.
Transitional Cell Carcinoma
Transitional cell carcinomas account for more than 90 percent of bladder cancer cases. In this type of cancer, the National Cancer Institute (NCI) reports that one type of cell that lines the wall of the bladder, called a transitional cell, becomes cancerous. One subtype of transitional cell carcinomas is papillary carcinoma, which is a more mild type of bladder cancer and grows superficially, in an outward direction. Another subtype of transitional cell carcinomas that is more severe is a sessile tumor, which tends to spread to other sites in the body early in the disease.
Squamous Cell Carcinoma
The NCI reports that approximately 8 percent of bladder cancer cases are squamous cell carcinomas. Squamous cells are the second type of cell that line the wall of the bladder. The Merck Manuals adds that this type of cancer usually affects patients who have a history of parasitic bladder infestation or chronic irritation of the bladder.
Adenocarcinomas
The American Cancer Society (ACS) states that only approximately 1 percent of bladder cancers are adenocarcinomas. This type of cancer begins in gland cells in the bladder. It is generally more severe than the other types of bladder cancer, because nearly all adenocarcinomas are invasive, meaning they grow through the bladder wall and can spread to other parts of the body.
Other Types
The ACS reports that other forms of bladder cancer are very rare, making up less than 1 percent of all bladder cancer cases. Types of very rare bladder cancer include small-cell carcinoma and sarcoma, which involves the muscle cells that surround the bladder.
