Undestanding Bladder Cancer

What is Bladder Cancer?

Last updated and reviewed on May 21, 2026.

Bladder cancer is a disease where cells in your bladder start growing out of control. Normally, your body makes new cells only when it needs them. But with cancer, something goes wrong, and cells keep multiplying even when they shouldn't. Over time, these extra cells form a mass called a tumor.

What is the bladder?

The bladder is a small, hollow organ in the lower part of your belly, sometimes called the pelvis. It is shaped like a balloon and is made of layers of stretchy muscle tissue. The bladder's main job is to store urine after it is made by your kidneys. 

The inside of the bladder is lined with special cells called urothelial cells (sometimes called transitional cells). These cells are very good at stretching and shrinking as the bladder fills and empties. Below this inner lining are layers of muscle and tissue that give the bladder its shape and strength.

The bladder is connected to two tubes called ureters, one coming from each kidney. Urine travels from the kidneys down the ureters and into the bladder, where it is stored until you are ready to urinate. The bladder can usually hold about 16 ounces (about two cups) of urine comfortably.

Keeping the bladder healthy is important for many reasons. When the cells lining the bladder begin to grow in an uncontrolled way, cancer can develop. Understanding how the bladder works helps explain why certain symptoms, like blood in the urine or a strong need to urinate, can be early warning signs of a problem.

How does bladder cancer start

Cancer starts when normal cells in the body begin to change and grow in an out-of-control way. In a healthy body, cells grow, divide, and die in an orderly way. But sometimes, the instructions inside a cell called DNA get damaged or changed. When this happens, the cell may start to grow and divide much faster than it should, and old or damaged cells do not die off like they are supposed to. Over time, these extra cells pile up and can form a growth called a tumor.

Bladder cancer starts when the cells lining the inside of the bladder develop these kinds of changes. Many things can damage the DNA inside bladder cells. For example, when harmful chemicals pass through the urine and stay in contact with the bladder lining for a long time, they can slowly damage the cells over many years. This is why some people who were exposed to certain chemicals or who smoked cigarettes for a long time have a higher chance of getting bladder cancer.

Where Does It Start?

Almost all bladder cancers begin in the inner lining of the bladder, the layer of urothelial cells that touches the urine. This makes sense because these cells are the ones most often exposed to the chemicals that pass through urine. When cancer starts in these cells, it is called urothelial carcinoma (or transitional cell carcinoma), and this is by far the most common type of bladder cancer.

Bladder cancer can start in different parts of the bladder, the sides, the back wall, the bottom (floor), or near where the ureters connect. The tumor may start as a small, mushroom-shaped growth on the surface of the lining, or it may start as a flat, reddish patch. In the early stages, the cancer is usually only in the inner lining and has not grown into the deeper muscle layer of the bladder.

How does bladder cancer affect the body?

Bladder cancer can affect the body in many different ways, depending on how advanced it is. In the early stages, the most noticeable symptoms are:

• Blood in the urine, which may make the urine look pink, orange, or red. Some people do not feel any pain at this stage, which is why bladder cancer is sometimes called a "silent" disease in its early form. The blood may come and go, and some people mistakenly think it has gone away on its own.

• Pain or burning when urinating, a need to urinate more often than usual, or a feeling that you need to go right away but cannot. If the tumor grows large enough to block the flow of urine, it can cause the urine to back up into the kidneys, which can be painful and damage the kidneys over time.

When bladder cancer has spread to other parts of the body (called metastatic cancer), it can cause more serious symptoms. These may include:

• Pain in the lower back or pelvis

• Swelling in the legs

• Loss of appetite

• Unintended weight loss

• Fatigue.

If the cancer spreads to the bones, it can cause bone pain. When it spreads to the lungs, it may cause difficulty breathing or a cough. Advanced bladder cancer can make it very difficult for the body to function normally.

Learn more about the signs and symptoms of bladder cancer. 

Types of bladder cancer

There are several types of bladder cancer, and they are named after the type of cell where the cancer started ¹.

• Urothelial Carcinoma (also called Transitional Cell Carcinoma): This is by far the most common type. It starts in the urothelial cells that line the inside of the bladder. Urothelial carcinoma makes up more than 90% of bladder cancer cases. It can look like small, finger-like growths sticking into the bladder (called papillary tumors) or flat, aggressive growths that spread along the bladder lining (called flat or carcinoma-in-situ tumors).

• Squamous Cell Carcinoma: This type starts in thin, flat cells that can form in the bladder lining after long-term irritation or infection. It is rare, 1-2% in the United States, but more common in parts of the world where a parasitic infection called schistosomiasis is common.

• Adenocarcinoma: This type starts in gland-like cells and is quite rare, 1%. It tends to be more aggressive than other types.

• Small Cell Carcinoma of the Bladder: This is a very rare and aggressive type that starts in nerve-like cells in the bladder wall. It is treated differently from other bladder cancers, often using similar approaches to small-cell lung cancer.

• Sarcoma: This very rare type starts in the muscle or connective tissue of the bladder wall, rather than in the lining cells.

What are the related disorders to bladder cancer?

Several other conditions of the bladder and urinary system are related to or can be confused with bladder cancer. Understanding these can help you and your doctor make sure you get the right diagnosis.

• Hematuria (Blood in the Urine): This is not a disease itself, but it is the most common reason people are checked for bladder cancer. Blood in the urine can be caused by many things, including bladder infections, kidney stones, or bladder cancer. Any unexplained blood in the urine should always be checked by a doctor.

• Bladder Infection (Cystitis): A bladder infection causes irritation, burning, and frequent urination symptoms that can look a lot like bladder cancer. Chronic or repeated infections can also irritate the bladder lining over time, which may slightly raise cancer risk.

• Urinary tract infections (UTIs): Can cause many of the same symptoms as bladder cancer, including blood in the urine, frequent urination, and burning during urination.

• Bladder stones: Hard mineral deposits that can form inside the bladder can also cause blood in the urine and pain.

• Interstitial Cystitis: This is a long-term condition that causes bladder pain, pressure, and urinary symptoms but is not caused by infection. It is not cancer, but its symptoms can overlap with bladder cancer symptoms.

• Benign Bladder Tumors: Not all bladder growths are cancerous. Some tumors in the bladder are benign (not cancerous), such as papillomas. However, because some benign growths can turn into cancer over time, they still need to be monitored closely.

• Upper Urinary Tract Urothelial Cancer: Cancer can also start in the urothelial lining of the kidneys or the tubes (ureters) connecting the kidneys to the bladder. This is closely related to bladder cancer and is treated in a similar way. People who have had bladder cancer are at higher risk for these upper tract cancers as well.

• Carcinoma in situ (CIS): Is a special type of bladder condition that is technically an early-stage bladder cancer but looks very different from typical tumors. Instead of forming a lump, it appears as a flat, reddish patch on the bladder lining. CIS is considered high-grade and can progress to invasive cancer if not treated.

Genetic and inherited risk factors

Bladder cancer can be influenced by both the genes you inherit and the environment around you. Most cases of bladder cancer are not caused by inherited genes alone; they result from a combination of lifetime exposures and genetic changes that happen in bladder cells over time.

Genetic Factors: Some gene changes inside bladder cells are found very often in bladder cancer. Mutations in genes called FGFR3 and TP53 are two of the most common. Changes in genes such as CHEK2, ATM, and BRCA2, also known for their role in breast cancer, have been linked to a higher risk of bladder cancer. People who carry mutations related to Lynch syndrome (a hereditary condition involving DNA repair genes like MLH1 and MSH2) have a significantly higher chance of developing bladder cancer.

Environmental and Lifestyle Risk Factors: Cigarette smoking is the single biggest risk factor for bladder cancer. The harmful chemicals in tobacco smoke are filtered through the kidneys and stored in urine, directly exposing the bladder lining to carcinogens. Exposure to certain industrial chemicals, such as those used in dyes, rubber, leather, and paint, is another important risk factor. Exposure to arsenic in drinking water and some chemotherapy drugs used for other cancers has also been linked to higher bladder cancer risk.

Related Cancers

Bladder cancer is closely related to several other cancers, particularly cancers that affect the urinary system and those that share the same types of cells.

• Upper Tract Urothelial Cancers: These cancers start in the same type of cells (urothelial cells) that line the kidneys' inner collecting system (called renal pelvis cancer) or the tubes connecting the kidneys to the bladder (called ureteral cancer). People who have had bladder cancer have a higher risk of developing these upper tract cancers, and vice versa.

• Kidney Cancer (Renal Cell Carcinoma): While this is a different type of cancer than bladder cancer, it affects a nearby organ in the urinary system. People with Lynch syndrome are at higher risk for both bladder and kidney cancer.

• Prostate Cancer: In men, prostate cancer and bladder cancer can sometimes occur together. The prostate sits just below the bladder, so advanced bladder cancer can sometimes affect the prostate as well.

• Lynch Syndrome-Related Cancers: People with Lynch syndrome are at higher risk for several cancers, including colorectal cancer, uterine cancer, and urinary tract cancers including bladder cancer.

• Cancers From Prior Treatment: People who have been treated for other cancers using certain chemotherapy drugs (like cyclophosphamide) or pelvic radiation therapy have a higher risk of developing bladder cancer later in life. This is why long-term follow-up after cancer treatment is so important.

SOURCES: [Behind drop-down]

1. https://www.cancer.org/cancer/types/bladder-cancer/about/what-is-bladder-cancer.html