Cancer Types – Bladder Cancer
Bladder Cancer: Overview
About the bladder, renal pelvis, and ureter
The bladder is an expandable, hollow organ in the pelvis that stores urine before it leaves the body during urination. This function makes the bladder an important part of the urinary tract. The urinary tract is also made up of the kidneys, ureters, and urethra. The renal pelvis is a funnel-like part of the kidney that collects urine and sends it into the ureter. The ureter is a tube that runs from each kidney into the bladder. The urethra is the tube that carries urine out of the body. In men, the prostate is also part of the urinary tract.
The bladder, like other parts of the urinary tract, is lined with a layer of cells called the urothelium. This layer of cells is separated from the bladder wall muscles, called the muscularis propria, by a thin, fibrous band called the lamina propria.
About bladder cancer
Bladder cancer begins when healthy cells in the bladder lining, most commonly urothelial cells, change and grow out of control, forming a mass called a tumor. Urothelial cells also line the renal pelvis and ureters. Although cancer that develops in the renal pelvis and ureters is considered a type of kidney cancer, it is treated in the same way as bladder cancer and is described in this guide. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. Benign bladder tumors are rare.
Types of bladder cancer
The type of bladder cancer depends on how the tumor’s cells look under the microscope. The 3 main types of bladder cancer are:
- Urothelial carcinoma. Urothelial carcinoma (or UCC) accounts for about 90% of all bladder cancers. It also accounts for 10% to 15% of kidney cancers diagnosed in adults. It begins in the urothelial cells found in the urinary tract. Urothelial carcinoma is sometimes also called transitional cell carcinoma or TCC.
- Squamous cell carcinoma. Squamous cells develop in the bladder lining in response to irritation and inflammation. Over time, these cells may become cancerous. Squamous cell carcinoma accounts for about 4% of all bladder cancers.
- Adenocarcinoma. This type accounts for about 2% of all bladder cancers and develops from glandular cells.
There are other, less common types of bladder cancer, including sarcoma and small cell anaplastic cancer. Sarcoma begins in the fat or muscle layers of the bladder. Small cell anaplastic cancer is a rare type of bladder cancer that is likely to spread to other parts of the body.
Other ways of describing bladder cancer
In addition to its cell type, bladder cancer may be described as noninvasive, non-muscle-invasive, or muscle-invasive.
- Noninvasive. Noninvasive bladder cancer includes noninvasive papillary carcinoma and carcinoma in situ (CIS). Noninvasive papillary carcinoma is a growth found on a small section of tissue that is easily removed. This is called stage 0a. CIS is cancer that is found only on or near the surface of the bladder, which is called stage 0is. See Stages and Grades for more information.
- Non-muscle-invasive. Non-muscle-invasive bladder cancer typically has only grown into the lamina propria and not into muscle, also called stage I. Non-muscle invasive cancer may also be called superficial cancer, although this term is being used less often because it may incorrectly suggest that this type of cancer is not serious.
- Muscle-invasive. Muscle-invasive bladder cancer has grown into the bladder’s wall muscle and sometimes into the fatty layers or surrounding tissue outside the bladder.
It is important to note that non-muscle-invasive bladder cancer has the possibility of spreading into the bladder muscle or to other parts of the body. Additionally, all cell types of bladder cancer can spread beyond the bladder to other areas of the body through a process known as metastasis.
If a bladder tumor has spread into the surrounding organs, such as the uterus and vagina in women, the prostate in men, and/or nearby muscles, it is called locally advanced disease. Bladder cancer also often spreads to the lymph nodes in the pelvis. If it has spread into the liver, bones, lungs, lymph nodes outside the pelvis, or other parts of the body, the cancer is called metastatic disease. This is described in more detail in Stages and Grades.
Read more about bladder cancer here.