Understanding Terms Used to Describe Bladder Cancer

Male bladder anatomy, illustration

If you or a loved one has been recently diagnosed with bladder cancer, it is important to spend some time processing the information. While you may be experiencing a range of emotions from anger to disbelief, you should feel good that you are already taking the first steps to coping with this new diagnosis—gaining knowledge about it.

Here is an overview of bladder cancer, starting with the basics of what the bladder is, how cancer develops, and the terms used to describe different types of bladder cancers.

The Urinary Tract System

The urinary system consists of the following organs:

The kidneys are two bean-shaped organs located in the back of the abdomen, beneath the diaphragm on the left side and beneath the liver on the right side. Your kidneys have three main functions:

  • filter waste from your blood
  • make urine
  • regulate your blood pressure and salt and water balance in your body

When urine is produced by the kidneys, it travels through a tube connected to each kidney called a ureter. The ureters are lined with muscles and nerves that act to drive the urine down into the bladder.

The bladder is a hollow, muscular organ that stores urine—around 2 cups at a time—and is located in the pelvis. When you urinate, contraction of the bladder, which is controlled by your brain and spinal cord, releases urine out of the bladder into the urethra—a duct that carries urine outside of the body.

In men and women, the urethra serves the same function. Although in men, the urethra does pass through the prostate gland, a walnut-sized organ that is located near the bottom of the bladder. While the prostate gland is involved in fertility in men, it does not contribute much to a man's urine flow.


Organs are made up of cells, and in a healthy organ, the cells grow and divide in a controlled, orderly fashion. But, sometimes, cancer may occur—when the cells within an organ begin growing and dividing in an uncontrolled manner. These cancer cells then keep multiplying and eventually form a tumor or mass that can then invade nearby healthy tissues, affecting their function and potentially causing symptoms (for example, blood in the urine or pain).

If not treated, cancer can enter the bloodstream and/or nearby lymph nodes and spread to other parts of the body.

The Meaning of "Bladder Cancer"

The bladder consists of multiple layers, and each layer is made up of different cells that serve a different function. The innermost layer of the bladder—called the urothelium—is where most bladder cancers begin. The cells in the innermost layer are called transitional cells, which is why you may have heard the term transitional cell carcinoma or urothelial carcinoma. (Carcinoma is another word for cancer). The transitional cells stretch when the bladder is full of urine, and shrink when the bladder is empty.

Just outside the urothelium is a thin layer of blood vessels and nerves followed by a thick muscular layer, and then finally a layer of fat.

As the bladder cancer grows, it can expand into or through these layers—once a bladder cancer has expanded into the thick muscular later, it is considered to be invasive, which means it is more difficult to treat. Superficial or non-invasive bladder cancer is easier to treat, as it is contained.

The big picture here is that the more the bladder cancer expands out, the more advanced it becomes, and the more challenging it can be to treat. Eventually, bladder cancer can spread to areas outside the bladder or even other organs, like the bones, liver, or lung—this process is called metastasis.

Stages and Grades of Bladder Cancer

Determining how far a person's bladder cancer has spread is called staging, and this is a very important aspect of a doctor's evaluation, as it dictates a person's treatment plan.

The grade of bladder cancer is also an important part of a doctor's evaluation and refers to how the cancer cells look under a microscope. Bladder cancer can be either low-grade or high-grade, with low-grade meaning that the cancer cells look more like healthy bladder cells, and high-grade meaning the cancer cells appear abnormal and not like healthy bladder cells.

A low-grade bladder cancer rarely spreads into the muscle layer of the bladder whereas a high-grade cancer is more likely too. Overall, this means that a low-grade bladder cancer generally offers patients a better chance of recovery.

Types of Bladder Cancer

Urothelial cancer: Urothelial carcinoma (also known as transitional cell cancer) is the most common type of bladder cancer (occurring in 90 to 95 percent) and it has two subtypes:

  • papillary carcinoma
  • flat carcinoma

These subtypes describe how the bladder cancers appear and grow within the bladder. A papillary carcinoma looks like a finger and grows from the innermost layer of the bladder (the urothelium) towards the center. Because they grow toward the center, they tend to avoid invading the outer layers of the bladder.

A flat carcinoma looks like a flat mass or growth lying on the innermost surface of the bladder. Unlike papillary carcinomas, they do not grow towards the center.

Cigarette smoking is the biggest risk factor for developing urothelial carcinoma and accounts for half of all cases of bladder cancer in the United States.

Squamous cell cancer: Besides urothelial carcinoma, there are other types of non-urothelial bladder cancers, but these are not very common. For example, squamous cell carcinoma of the bladder begins in skinny, flat cells called squamous cells that may form in the bladder after long-term infection.

A classic example of squamous cell carcinoma of the bladder is in a person infected with the parasite Schistosoma haematobium, found in African and the Middle East. Chronic urinary tract infections or irritation from an indwelling catheter may also be risk factors for developing this type of bladder cancer.

Adenocarcinoma of the bladder is a rare type, accounting for approximately 1 to 2 percent of all bladder cancers in the United States. Like squamous cell carcinoma, infection with the parasite Schistosoma haematobium or chronic irritation of the bladder can increase a person's chance of developing this type of bladder cancer.

Others: There are other less common types of bladder cancer like small cell carcinoma of the bladder and melanoma. Overall, treatment is generally similar for early-stage bladder cancer (regardless of the type), although chemotherapy may vary.

A Word From Verywell

Whether you or a loved one has been diagnosed with bladder cancer (or you simply want to learn more about it), remain proactive in your bladder and overall health. In the end, try not to get too bogged down in the details—stick with the big picture, file some of the terms away, and be sure to address any questions or worries with your doctor.


American Cancer Society. (January 2016). What is Bladder Cancer?

Dadhania V, Czerniak B, Guo CC. Adenocarcinoma of the urinary bladder. Am J Clin Exp Urol. 2015; 3(2):51-63.

McNeil, B. (2011). First Steps—I've Been Diagnosed with Bladder Cancer. In Gonzalgo ML (Ed), Patient's Guide to Bladder Cancer (1-6). Massachusetts: Jones and Bartlett Publishers.

Sharma S, Ksheersagar P, Sharma P. Diagnosis and treatment of bladder cancer. Am Fam Physician. 2009 Oct 1;80(7):717-23.

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