What is Bladder Cancer?

What is bladder cancer?

Bladder cancer most often begins in the urothelial cells that line the inside of your bladder.  Cancer occurs when cells in the bladder start to grow out of control.  Most tumors develop on the inner layer of the bladder. Some can grow into deeper bladder layers. As cancer grows through these layers into the muscle wall, it becomes harder to treat. Urothelial cells are also found in your kidneys and the ureters, the tubes that connect the kidneys to the bladder. Bladder cancer can happen in the kidneys and ureters, too, though much less frequently.

Types of bladder cancer

There are several types of bladder cancer, but the most common diagnosis when you have bladder cancer is urothelial carcinoma. This is also known as transitional cell carcinoma, and it occurs in the urothelial cells lining the interior part of your bladder.

Urothelial cells are also in other parts of your urinary system, such as your kidneys, ureters, and your urethra. If you are diagnosed with bladder cancer, it is possible that tumors could be discovered in these areas of your body too. Your entire urinary tract will be examined to check for tumors.

Although transitional cell, or urothelial cancer, is the most common type of bladder cancer, some individuals will  be diagnosed with another rarer types of bladder cancer.

Muscle invasive vs non-muscle invasive bladder cancer

How quickly a cancer spreads is a concern, and bladder cancers are defined by how far they have spread, and whether they have reached deeper levels of the bladder and beyond.

Invasive bladder cancers are more difficult to treat, as they often grow further into the walls of the bladder and beyond.

Non-invasive bladder cancers are discovered in the inner layer of cells, and they have not grown further into the deep layers of the bladder. They are easier to treat because they haven’t spread.

Two other descriptors of bladder cancer are superficial, or non-muscle invasive. Both can be used to describe a cancer that is non-invasive, and one that is invasive, but hasn’t spread into deeper layers of the bladder muscle yet.

Rare types of bladder cancer

Squamous cell carcinoma

Of all the bladder cancer cases discovered in the United States, squamous cell carcinoma is only 1% to 2% of the cases. If you look at the cells under a microscope, they are similar to skin cells found on the surface of your skin.


Like squamous cell carcinoma, adenocarcinoma bladder cancer makes up roughly 1% of all bladder cancer cases. The cancer cells of adenocarcinoma are similar to the gland-forming cells found in colon cancers

Small cell carcinoma

With origins in the neuroendocrine cells, small-cell carcinomas are rare and make up less than 1% of all bladder cancers. This is a fast-growing cancer, and chemotherapy is a common treatment of this type of bladder cancer.


Sarcomas are a rare type of bladder cancer that originates in the muscle cells of the bladder.

FAQ About Bladder Cancer

How will my bladder cancer be treated?

This depends on whether your cancer is invasive, non-invasive, and if the cancer has spread. Surgical removal of tumors, radiation, and possibly chemotherapy can all help to treat bladder cancer.

What does it mean if I have advanced bladder cancer?

If you have advanced bladder cancer, this means that the cancer is either large, or has already spread to other areas of your body. This can cause problems urinating, loss of appetite, exhaustion, and lower back pain.

What does your bladder do?

Your bladder is part of your urinary system. The job of the urinary system is to filter waste products from your blood and transport the waste products or urine, out of your body. The diagram below shows the organs of the urinary system.

Most of the urinary tract is lined with a special layer of cells called transitional cells. The primary “machines” in the human filtering system are the two kidneys located close to the backbone and protected by the ribs. The kidneys work independently. They have the significant task of filtering approximately 20% of total blood volume each minute and removing the by-products of digestion and of other body functions.

Once produced, the urine (the filtered waste product) is stored in the central part of the kidney called the renal pelvis. At regular intervals, the renal pelvis contracts and propels the urine through the ureters. These narrow, thin-walled tubes extend from inside the renal pelvis to the bladder. The bladder is a thick-walled structure, consisting of a relatively thin inner layer with a thick muscle covering.

This inner layer or epithelium is made of several layers of cells. The epithelial layer is also called the transitional cell layer. The main function of the bladder is to store urine. For most people, the bladder can hold as much as 1 pint (16 ounces) of urine at a time. It contracts or expands depending on how much fluid is in it. When it contracts following a series of neurological “messages” to the brain and spinal cord, the urine moves through the urethra outside the body.

Video: Preparing for your bladder cancer consultation