The short answer
Urothelial carcinoma, also called transitional cell carcinoma, is by far the most common type of bladder cancer. Squamous cell carcinoma, adenocarcinoma, and small cell carcinoma are much rarer and are treated differently.
Urothelial (transitional cell) carcinoma is by far the most common type of bladder cancer.
Squamous cell carcinoma makes up about 3 to 5 percent of bladder cancers.
Adenocarcinoma makes up about 1 to 2 percent of bladder cancers.
Small cell carcinoma and sarcoma are very rare bladder cancer types.
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The full explanation.
The simple version
Most bladder cancer is one type. A small share are rarer types. These rarer types behave, and are treated, differently.
The common type
Urothelial carcinoma is also called transitional cell carcinoma. It accounts for almost all bladder cancers. It starts in urothelial cells. These cells line the inside of the bladder. They can stretch and shrink as the bladder fills and empties. That is why they are also called transitional cells. Most bladder cancer research, and most standard treatments, are built around this one type.
Rarer types
- Squamous cell carcinoma. Makes up about 3 to 5 percent of bladder cancers. It is often linked to long-term bladder irritation, such as from a chronic infection. In some parts of the world, it is linked to a parasite called schistosomiasis.
- Adenocarcinoma. Makes up about 1 to 2 percent of bladder cancers. It starts in gland cells, not urothelial cells. These cells normally make mucus and other fluids.
- Small cell carcinoma. Makes up less than 1 percent of bladder cancers. It starts in neuroendocrine cells, which send hormone-like signals in response to nerve activity. It tends to grow and spread quickly. It often needs chemotherapy like the kind used for small cell lung cancer.
- Sarcoma. A very rare bladder cancer. It starts in connective tissue, such as muscle.
In short: urothelial carcinoma accounts for the large majority of cases. Squamous cell carcinoma, adenocarcinoma, small cell carcinoma, and sarcoma make up the rest.
Another way doctors describe bladder cancer
Doctors also classify bladder cancer by how deep it has grown into the bladder wall. This is separate from cell type. Non-muscle-invasive bladder cancer is the more common pattern. It has not grown into the muscle layer of the bladder wall. Muscle-invasive bladder cancer has grown into or through that muscle layer. It generally needs more aggressive treatment. Your team will describe your cancer using both its cell type and this depth of invasion. Each piece carries different information.
Why type matters for treatment
Urothelial carcinoma is so common that many bladder cancer drugs were built around it. This includes many chemotherapy and immunotherapy protocols. Squamous cell carcinoma, adenocarcinoma, and small cell carcinoma often respond differently. They may need a different combination of surgery, chemotherapy, or radiation. A standard urothelial-carcinoma protocol may not apply to them. Confirming the exact type through pathology review matters. It helps your care team choose the treatment most likely to work for your specific cancer.
What to ask your team
Ask what type of bladder cancer you have. Ask how confident the pathology report is in that type. Ask whether your cancer is muscle-invasive or non-muscle-invasive, and how that relates to your type. Ask whether your specific type changes which treatments are options for you. Ask how the type was confirmed, and whether more testing is planned.
Sources
Words to know
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Common questions
What is the most common type of bladder cancer?
Urothelial carcinoma, also called transitional cell carcinoma, is by far the most common type. It starts in the urothelial cells that line the inside of the bladder.
What is squamous cell carcinoma of the bladder?
This type makes up only about 3 to 5 percent of bladder cancers. It is more often linked to long-term bladder irritation or infection than urothelial carcinoma is.
Is adenocarcinoma of the bladder common?
No, it is rare, making up only about 1 to 2 percent of bladder cancers. It starts in gland cells rather than the urothelial cells that line most of the bladder.
Does the type of bladder cancer change my treatment?
Yes. Most bladder cancer treatments, including many chemotherapy and immunotherapy drugs, are developed and studied specifically for urothelial carcinoma. The rarer types often call for a different approach.
Questions to ask your doctor
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Last updated: 2026-08-05Next planned review: 2027-08-03
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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