OncoLink en espanõl
Types of Cancer > Urinary Tract Cancers > Bladder Cancer > Overview
Bladder Cancer: The Basics
Ryan P. Smith, MDRyan P. Smith, MD and Christine Hill-Kayser, MD
Affiliation:
Abramson Cancer Center of the University of Pennsylvania
Last Modified: February 24, 2008
What is the Bladder?
The bladder serves as a reservoir for urine in our bodies. It permits the storage of urine for a period of time before releasing it as we urinate. It can be thought of as a muscular balloon; it is a flat structure when there is no urine (immediately after a person urinates), but is able to fill up to a liter or so of urine when needed (though this would be very uncomfortable). Normally, as the bladder nears 500 cc (1/2 of a liter), we feel the urge to urinate. The muscular structure of the bladder also helps other pelvic muscles push the urine out when it is released. The bladder is located deep in the pelvis, just above the pubic symphysis, which is a bone that can be felt in the midline on the front of the pelvis. In fact, when the bladder is over distended, it can be felt by a physician. Ureters empty urine into the bladder from the kidneys, and the urethra leads out from the bladder, emptying urine out of our bodies.
What is bladder cancer?
A tumor is a mass of abnormally growing cells. Tumors can be either benign or malignant. Benign tumors may grow in an uncontrolled way, but without any invasion into normal tissues and without any risk of spreading to distant parts of the body. Tumors are malignant (or “cancer”) when cells gain the propensity to invade tissues and spread locally as well as to distant parts of the body. In this sense, bladder cancer occurs when cells in the lining of the bladder grow uncontrollably and form tumors that can invade normal tissues and spread to other parts of the body.
Cancers are described by the types of cells from which they arise. Bladder cancers arise almost exclusively from the lining of the bladder. In the United States, 98% of bladder cancers are called transitional cell carcinomas. This simply means that the cancer started in the lining of the bladder, which is made up of transitional cells that appear elliptical under the microscope. Less commonly, other types of cancers can arise from the lining of the bladder, called adenocarcinomas, squamous cell carcinomas and small cell carcinomas.
Commonly, bladder cancers grow in a “papillary” growth pattern. When a bladder cancer grows this way, it can be noninvasive, i.e., not invading into tissues at all, and hence not having a risk for distant spread (as long as it is treated). In addition to other invasive cancers, patients are sometimes diagnosed with precancerous lesions, called carcinoma-in-situ. Carcinoma-in-situ occurs when the lining of the bladder undergoes changes similar to cancerous changes without any invasion into the deeper tissues. Hence, while the cells themselves have cancer-like qualities, there is no risk of spread, as no invasion has occurred. However, both papillary bladder cancers and cancer-in-situ may become invasive, so treatment is very important.
Am I at risk for bladder cancer?
Bladder cancer is the fourth most common cancer in men and the eighth most common cancer in women. Over 50,000 cases are diagnosed every year in the United States, with over 12,000 deaths. Internationally, the incidence of transitional cell bladder cancer varies substantially, with highest rates in Europe and North America. In Northern Africa, where infectionwith a type of parasite called Schistosoma haematobium is common squamous cell carcinomas of the bladder are more common. Classically, in the US, bladder cancer is thought of as a disease that affects older men, with men affected more than women by a 3:1 ratio and 2/3 of the cases diagnosed in people over the age of 65.
Cigarette smoking is the largest risk factor for bladder cancer (yet another reason to stop smoking). Smokers have 2-4 times the risk of having bladder cancer, and it contributes to up to 50% of all bladder cancers that are diagnosed. Chronic bladder irritation, from either stones or long-term catheter use, may increase risk of bladder cancer. Occupational exposures, such as polychromatic hydrocarbons (benzene, benzidine), can increase risk of bladder cancer. Recently, an association has been made between chlorinated drinking water and bladder cancer. Though there have been suggestions of saccharin and high intake of dietary fat and cholesterol being causative for bladder cancer, these have yet to be substantiated.The previously mentioned Schistosoma haematobium infections may also increase risk of squamous cell carcinoma of the bladder; this parasite is present mainly in regions of North Africa such as Egypt.,