The Types of Bladder Cancer
- Bladder cancer develops when cells that make up the urinary bladder start to grow and eventually develop into tumors. It is the fifth most common cancer in the American population.
- The most common type of bladder cancer, urothelial carcinoma, occurs when urothelial cells cells that line the inside of the bladder or other parts of the urinary tract become cancerous.
- For patients who have invasive bladder cancer, one of our experts says they worry that since the cancer has already figured out how to creep into the bladder wall, it will continue to grow and spread outside of the bladder if given enough time.
“Bladder cancer is one of those cancers that you don't hear about too often, which has always been surprising to me because it is the fifth most common cancer that we see in the American population,” Dr. Jay Shah, the cancer care program leader for urologic oncology at the Stanford Cancer Center, previously told SurvivorNet.
Read MoreTypes of Bladder Cancer
Urothelial carcinoma: The most common type of bladder cancer is called urothelial carcinoma. This type occurs when urothelial cells cells that line the inside of the bladder or other parts of the urinary tract become cancerous. “So, bladder cancer's an anatomic term, but urothelial cancer is a description of what the cells look like under the microscope,” Dr. Arjun Balar, director of the genitourinary medical oncology program at NYU Langone's Perlmutter Cancer Center, tells SurvivorNet. “And that term came around because ‘uro’ means urinary, and ‘thelium’ means lining. So, it's just a different way of describing the urinary lining.”Adenocarcinoma: 1 in 100 bladder cancers are adenocarcinomas, which have a higher likelihood of being invasive at diagnosis. This type of bladder cancer develops from glandular (secretory) cells in the lining of the bladder.
Sarcoma: This type of bladder cancer is rare and found in the muscle cells of the bladder. Bladder sarcomas tend to form in the area between the openings of the ureters and the urethra, but they can also develop in the entire bladder area.
Squamous cell carcinoma: About 5 percent of bladder cancer patients have squamous cell carcinoma. The cells in this type have a higher chance of becoming invasive. It is associated with chronic irritation of the bladder which can be caused by things like long-term use of a urinary catheter or an infection.
Small cell carcinoma: This bladder cancer is very rare and starts in neuroendocrine (nerve-like) cells. It is a highly aggressive cancer that tends to be caught at advanced stages of the disease.
Dr. Balar notes that about 5-10 percent of patients will have a bladder cancer that is an adenocarcinoma, which has a higher likelihood of being invasive at diagnosis, or squamous cell carcinoma, which has a higher likelihood of becoming invasive. Sarcomas in the muscle cells of the bladder and small cell carcinomas of neuroendocrine (nerve-like) cells can also be types of bladder cancer, but these are the most rare types of bladder cancer.
Location of Bladder Cancer
A big concern for doctors treating bladder cancer patients is the location of the disease. First of all, it’s important to understand that bladder cancer can actually occur in other parts of the urinary tract not just within the bladder.
“The urinary tract starts up at the kidneys, and then there are tubes that bring urine down from the kidneys into the bladder. Those tubes are called ureters,” Dr. Shah said. “And then there’s the bladder which stores the urine, and the urethra, which is how we empty the urine.”
In order to understand the different classifications of bladder cancer tumors, it’s important to consider the following terms used to classify where the bladder cancer cells are located:
- Non-Muscle Invasive: The tumors can be found in the top layer of cells and are confined to the bladder, these cancers are at stage 0 or 1.
- Superficial: This term can be applied to both non-invasive and invasive tumors that have not spread to the main muscle layer of the bladder; these cancers are at stage 0 or 1. In order for it to be a superficial invasive tumor, the cancer would have had to grow into the connective tissue layer of the bladder wall but not reach the muscle layer, or bladder wall.
- Muscle Invasive: The cancer has grown into deeper layers of the bladder wall.
- Metastatic: The cancer has spread to the abdominal wall, lymph nodes and other areas far from the bladder, also called stage 4 bladder cancer.
“Within bladder cancer, we have tumors that can grow into the lining and outward into the lumen [inside space] of the bladder. We call those papillary tumors, or in situ cancers, which means that they don’t invade into the bladder wall, but they are simply present,” Dr. Balar explained. “And then they can become invasive, and we call those T1 tumors, or stage one tumors, which means that they invade into the first layer just below the urinary lining."
If the cancer becomes more invasive from there, they can spread to the muscle layer (wall) of the bladder which expands and contracts to allow for urination. For Dr. Balar and Dr. Shah, that’s where a dividing point exists in terms of how aggressive the cancer is.
“For patients who have invasive bladder cancer, we worry that this is a cancer that’s figured out how to creep into the wall, and, given enough time, it will continue to grow and creep, and creep out of the bladder,” Dr. Shah explained.
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