The three main types of bladder cancer are urothelial carcinoma, squamous cell carcinoma, and adenocarcinoma. These types are defined by the kind of cell where the cancer starts, and they differ significantly in how common they are, what causes them, and how they’re treated. Urothelial carcinoma dominates, making up about 90% of all bladder cancer cases in the U.S., while the other two are far less common.
Urothelial Carcinoma
Urothelial carcinoma, also called transitional cell carcinoma, is by far the most common form of bladder cancer. It begins in the urothelial cells that line the inside of your bladder. These cells are flexible, expanding and contracting as your bladder fills and empties. When one of these cells mutates and begins growing out of control, urothelial carcinoma develops.
Because it starts in the lining, urothelial carcinoma is often caught while it’s still superficial, meaning it hasn’t grown into the deeper muscle layers of the bladder wall. This distinction matters enormously for treatment. Non-muscle-invasive bladder cancer, where the tumor stays in the lining or the connective tissue just beneath it, is typically treated with procedures that preserve the bladder. Muscle-invasive bladder cancer, where tumor cells have pushed into the thick muscle wall, usually requires more aggressive treatment and often involves removing part or all of the bladder.
Early-stage urothelial carcinoma can take two different forms. One looks like thin, finger-like growths projecting into the hollow space of the bladder. The other is flat, spreading along the surface of the bladder lining. The flat form is always considered high-grade, meaning the cells look very abnormal and tend to be more aggressive. Both forms can progress to muscle-invasive disease if left untreated, but the flat type carries a higher risk of doing so.
Squamous Cell Carcinoma
Squamous cell carcinoma accounts for roughly 2% to 7% of bladder cancers. It develops from squamous cells, which are thin, flat cells that don’t normally exist in large numbers in the bladder lining. They appear when the bladder has been irritated or inflamed for a long time, causing the normal urothelial cells to gradually transform into squamous cells. This process is called metaplasia.
The biggest risk factors are things that cause ongoing bladder irritation. Long-term use of a urinary catheter is one common trigger. Chronic or repeated urinary tract infections also raise the risk. In parts of Africa and the Middle East, a parasitic infection called schistosomiasis is a major driver of squamous cell bladder cancer. The parasite lodges in the bladder wall and causes years of chronic inflammation, which eventually leads to cancerous changes in the cells.
Because squamous cell carcinoma develops from prolonged irritation, it tends to be diagnosed at a more advanced stage than urothelial carcinoma. It often grows as a solid mass rather than a papillary (finger-like) growth, and it may already be embedded in the muscle wall by the time symptoms prompt a visit to the doctor.
Adenocarcinoma
Adenocarcinoma is the rarest of the three main types, representing about 2% of bladder cancers. It starts in glandular cells, the type of cells that produce and release mucus. There are two distinct subtypes: urachal and non-urachal.
Urachal adenocarcinoma originates from a remnant of the urachus, a small tube that connects the bladder to the umbilical cord before birth. This tube normally closes and becomes a fibrous cord, but leftover tissue at the top (dome) of the bladder can sometimes become cancerous. These tumors tend to appear in younger patients and are more likely to produce mucin, a thick, gel-like substance. Treatment typically involves surgically removing the dome of the bladder along with the urachal remnant and the belly button, since the old tract runs between them.
Non-urachal adenocarcinoma develops elsewhere in the bladder and is thought to arise when chronically irritated urothelial cells transform into glandular cells over time, similar to the process behind squamous cell carcinoma. Five-year survival rates for both subtypes are in a comparable range, with urachal adenocarcinoma showing a possible advantage in more advanced cases.
Rare Types Beyond the Main Three
While urothelial, squamous cell, and adenocarcinoma are the three types you’ll see referenced in nearly every bladder cancer resource, a handful of extremely rare variants also exist. Small cell carcinoma of the bladder accounts for less than 1% of all bladder cancers and is notably aggressive. It behaves more like small cell lung cancer than like typical bladder cancer, growing quickly and spreading early. Other rarities include sarcomas, which start in the muscle or connective tissue of the bladder wall rather than in the lining cells.
How the Type Affects Your Experience
All three main types of bladder cancer share similar early symptoms: blood in the urine (often painless), frequent urination, or a persistent urge to urinate even when your bladder isn’t full. The type of cancer doesn’t change the initial symptoms much, but it shapes nearly everything that happens after diagnosis.
The cell type is determined through a biopsy, where a pathologist examines tissue samples under a microscope. They look at the shape and arrangement of the cells, how deeply the tumor has grown, and whether it has reached the muscle layer. For cases that are difficult to classify, special staining techniques and molecular testing can help distinguish between types.
Urothelial carcinoma has the broadest range of treatment options, in part because it’s so common that most clinical research has focused on it. Squamous cell carcinoma and adenocarcinoma don’t always respond to the same approaches, and treatment plans for these rarer types are often built around surgery, particularly bladder removal, since fewer drug-based therapies have been validated for them. Knowing your specific type is one of the most important pieces of information for understanding your treatment path and likely outcomes.