Types of Bladder Tumors

Bladder tumors are grouped into several types by how their cells look under a microscope.

The type of bladder cancer you have can affect your treatment options. This is because different types can respond differently to treatments such as radiation and chemotherapy. The main types of cancers that affect the bladder are:

• Transitional cell carcinoma (also called urothelial carcinoma)
• Squamous cell carcinoma
• Adenocarcinoma
• Small cell carcinoma

About 95% of bladder cancers are transitional cell carcinomas. The cells from transitional cell carcinomas look like the urothelial cells that line the inside of the bladder. Two very important traits in predicting the outlook for transitional cell carcinomas are the grade of the cancer and whether or not it is invasive.

These tumors are divided into grades based on how abnormal the cells look under the microscope. If the cells look more like normal cells, the cancer is called a low-grade cancer. When the cells look more abnormal, the cancer is high-grade. Lower-grade cancers tend to grow more slowly and have a better outcome than higher-grade cancers. If the cancer stays in the inner layer of cells without growing into the deeper layers, it is called non-invasive If the cancer grows into the lamina propria or deeper into the muscle layer, it is called invasive. Invasive cancers are more likely to spread and are harder to treat. You may also see a bladder cancer described as superficialor non-muscle invasive. These terms include both non-invasive tumors as well as any invasive tumors that have not grown into the main muscle layer of the bladder.

Transitional cell carcinomas are also divided into 2 subtypes, papillary and flat. Papillary carcinomas grow in slender, finger-like projections from the inner surface of the bladder toward the hollow center. Papillary tumors often grow toward the center of the bladder without growing into the deeper bladder layers. These tumors are called non-invasive papillary cancers. Very low-grade non-invasive papillary cancer is sometimes called papillary neoplasm of low-malignancy potential and tends to have a very good outcome. Flat carcinomas do not grow toward the hollow part of the bladder at all. If a flat tumor is only in the inner layer of bladder cells, it is known a non-invasive flat carcinoma or a flat carcinoma in situ (CIS). If either a papillary or flat tumor grows into deeper layers of the bladder, it is called an invasive transitional cell (urothelial) carcinoma.  More information about bladder cancer can be found at www.cancer.org.

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