What is Bladder Cancer?

Bladder cancer begins when cells in the bladder grow out of control. Most cases start in the urothelium that lines the inside of the bladder.  Bladder cancer is classified as non-muscle invasive or muscle-invasive based on whether it has grown into the bladder’s muscular wall. 

What does the bladder do?

The bladder is a hollow, muscular organ in the lower abdomen. Its main function is to store urine produced by the kidneys. 

The bladder is part of the urinary system, which includes: 

• Kidneys: Filter the blood and produce urine 

• Ureters: Carry urine from the kidneys to the bladder 

• Bladder: Stores urine 

• Urethra: Carries urine out of the body 

Where does bladder cancer begin? 

Most bladder cancer 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. Urothelial cancer can happen in the kidneys and ureters, too, though much less frequently. 

What are the main types of bladder cancer? 

There are several types of bladder cancer, but urothelial carcinoma is the most common bladder cancer.  

Rare types of bladder cancer are squamous cell carcinoma, adenocarcinoma, small cell carcinoma and sarcoma. 

Learn more about bladder cancer types, stages and grades. 

What is the difference between NMIBC and MIBC? 

Non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) differ in whether the cancer has grown into the bladder muscle.

Non-muscle invasive bladder cancer (NMIBC)

NMIBC has not grown into the muscular wall of the bladder. It may be limited to the inner lining or the connective tissue directly beneath it. 

Muscle-invasive bladder cancer (MIBC)

MIBC has grown into the bladder muscle. It may also grow through the bladder wall or spread beyond the bladder. 

This distinction helps doctors understand the cancer and recommend treatment. The cancer’s stage, grade and other pathology findings provide additional information about how it may behave. 

How common is bladder cancer? 

Bladder cancer is the 7th most commonly diagnosed cancer in the United States and the 3rd most common cancer in men. Each year, more than 84,000 people in the US will receive a bladder cancer diagnosis (American Cancer Society Cancer Facts and Figures report).

Bladder cancer is more common in men than in women and most people diagnosed with bladder cancer are older adults. However, anyone can develop bladder cancer. 

How is bladder cancer treated? 

This depends on the type of cancer and if it has spread. Surgical removal of tumors, radiation, and possibly chemotherapy can all help to treat bladder cancer. 

Frequently asked questions about bladder cancer 

Where does bladder cancer usually begin? 

Bladder cancer usually begins in the urothelial cells that line the inside of the bladder. These cells also line other parts of the urinary tract. 

What is the most common type of bladder cancer? 

Urothelial carcinoma is the most common type of bladder cancer in the United States. Less common types include squamous cell carcinoma, adenocarcinoma, small cell carcinoma and sarcoma. 

What is the difference between non-muscle invasive and muscle-invasive bladder cancer? 

Non-muscle invasive bladder cancer has not reached the bladder muscle. Muscle-invasive bladder cancer has grown into the muscular wall of the bladder. 

Learn more about bladder cancer 

• Bladder cancer signs and symptoms 

• Bladder cancer risk factors and causes 

• Bladder cancer diagnosis and monitoring 
• Bladder cancer treatment options 
• Video: Preparing for your bladder cancer consultation