The wall of the bladder has several layers. Cancer begins in the lining layer and grows into the bladder wall. As the cancer grows deeper into the layers of the wall of the bladder, it becomes harder to treat.

The wall of the bladder has several layers. Cancer begins in the lining layer and grows into the bladder wall. As the cancer grows deeper into the layers of the wall of the bladder, it becomes harder to treat.

The inside of the bladder is lined with a layer of cells called urothelial cells. The same type of cells also lines the kidneys, the tubes connecting the kidneys to the bladder (ureters), and the urethra. Cancer can begin in the lining cells in any of these structures which are part of the urinary system.

The bladder is a hollow organ that stores urine. Urine flows into the bladder from the kidneys, where it is made, through thin tubes called ureters. Urine empties from the bladder through another tube called the urethra. In women the urethra is very short. In men it is longer since it passes through the prostate gland to the tip of the penis.

The wall of the bladder has several layers. Cancer begins in the lining layer and grows into the bladder wall. As the cancer grows deeper into the layers of the wall of the bladder, it becomes harder to treat.

The inside of the bladder is lined with a layer of cells called urothelial cells. The same type of cells also lines the kidneys, the tubes connecting the kidneys to the bladder (ureters), and the urethra. Cancer can begin in the lining cells in any of these structures which are part of the urinary system.

Types of Bladder Cancer

There are 4 main types of bladder cancer. They are grouped by the way the cancer cells look under a microscope.

• Urothelial carcinoma: This is by far the most common type of bladder cancer. It starts in the urothelial cells. It is also called transitional cell carcinoma. Within this group are also several subtypes. They are named depending on the shape of the cells and whether they tend to spread and invade other organs (invasive).
• Squamous cell carcinoma: This type is much less common and is usually invasive.
• Adenocarcinoma: This type is also much less common and almost all are invasive.
• Small cell: A very small number of bladder cancers are of this type.
  

These 4 types of bladder cancer respond to treatment in different ways. For some people, the type of treatment they get can be influenced by the exact type of bladder cancer they have.

While there are other types of bladder cancer, they are very rare. There are also a number of bladder tumors that are benign (not cancer). Ask your doctor to explain to you exactly what type of tumor you have and what it means in your case.