Cancer is when cells in the body change and grow out of control. To help you understand what happens when you have cancer, let's look at how your body works normally. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer.
Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby areas. They can even spread to other parts of the body (metastasis).
The bladder is a hollow, balloon-like organ in the lower belly (pelvis). It holds liquid body waste called urine until it’s passed out of the body. Urine comes into the bladder through 2 tubes called the ureters. Each ureter is attached to a kidney. This is where urine is made. Urine leaves the bladder through a tube called the urethra. All of these organs make up the urinary tract.
The male and female urinary tracts:
One way to discuss bladder cancer is to describe what kind of cells it starts from. The bladder wall is made up of many layers of cells. It has an outer layer of muscle cells, and an inner lining layer of other kinds of cells. Bladder cancer can affect any one or all of these cells. These are the 3 types of cells that most commonly become bladder cancer:
Urothelial cells (or transitional cells). These cells make up the tissue that lines the inside of the bladder. This is called the urothelium. Cancer in this area is called urothelial carcinoma or transitional cell carcinoma (TCC). This is the most common type of bladder cancer.
Squamous cells. These look like cells from the surface of the skin. This type is rare, causing less than 1 in 25 of all bladder cancers.
Cells that make up glands. This type of bladder cancer is called adenocarcinoma. It’s very rare. Only 1 in 100 to 1 in 50 people with bladder cancer have this type.
Very rarely, cancers such as lymphoma, sarcoma, and small cell carcinoma can start in the bladder.
Another way to talk about bladder cancer is by how deeply it invades the layers of the bladder wall. This puts the cancer into 1 of 2 groups:
This is cancer that affects only the inner lining of the bladder (urothelial carcinoma or transitional cell carcinoma). It has not grown deeper into the bladder's muscle layer. After treatment, non-muscle invasive bladder cancer often comes back, usually as another non-muscle invasive cancer.
This cancer affects deeper layers of the bladder. This may include the outer muscular wall and other tissues that are nearby. Invasive bladder cancer is more likely to spread to nearby organs. These can include the kidneys, prostate gland (in men), and the uterus and vagina (in women). It may also spread to the lymph nodes. Lymph nodes are small, pea-sized storage units for special cells that fight infections. Almost all squamous cell bladder cancers and adenocarcinomas are invasive.
Transitional cell carcinomas (TCCs) may also be described as being either papillary or flat:
Papillary tumors. These look like small mushrooms and grow into the open part of the bladder. They rarely invade other parts of the bladder. Some types of papillary tumors tend to come back. But they're fairly easy to remove without damaging the bladder. These tumors may be superficial or invasive. Invasive bladder tumors go deep into the bladder wall and can spread to other parts of the body.
Flat tumors. These don't grow into the open part of the bladder. They may be either superficial or invasive.
If you have questions about bladder cancer, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.