Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
The bladder is a hollow organ in the lower abdomen
(pelvis). It collects and stores urine produced by the kidneys.
As it fills with urine, the muscular wall of the
bladder stretches and the bladder gets larger.
When the bladder reaches its capacity of urine, the
bladder wall contracts, although adults have voluntary control over the timing
of this contraction. At the same time, a urinary control muscle (sphincter) in the urethra relaxes. The
urine is then expelled from the bladder.
The urine flows through a narrow tube called the urethra and leaves the body. This process is called urination, or micturition.
Cancer occurs when normal cells undergo a transformation whereby they grow and multiply without normal controls.
As the cells multiply, they form an area of abnormal
cells. Medical professionals call this a tumor.
As more and more cells are produced, the tumor
increases in size.
Tumors overwhelm surrounding tissues by invading
their space and taking the oxygen and nutrients they need to survive and
Tumors are cancerous only if they are malignant. This
means that, because of their uncontrolled growth, they encroach on and invade
Malignant tumors may also travel to remote organs via the bloodstream or the lymphatic system.
This process of invading and spreading to other organs is called metastasis. Bladder
cancers are most likely to spread to neighboring organs and lymph nodes prior
to spreading through the blood stream to the lungs, liver, bones, or other organs.
Of the different types of cells that form the bladder,
the cells lining the inside of the bladder wall are most likely to develop
cancer. Any of three different cell types can become cancerous. The resulting cancers are named after the cell types.
Urothelial carcinoma (transitional cell carcinoma): This is by far the most common type of bladder cancer in the
United States. The so-called transitional cells are normal cells that form the
innermost lining of the bladder wall. In transitional cell carcinoma, these
normal lining cells undergo changes that lead to the uncontrolled cell growth
characteristic of cancer.
cancers form from cells that make up glands. Glands are specialized structures
that produce and release fluids such as mucus.
In the United States, urothelial carcinomas account for more than 90% of all bladder cancers. Squamous cell carcinomas make up 3%-8%, and adenocarcinomas make up 1%-2%.
Only transitional cells normally line the rest of the urinary tract. The
kidneys, the ureters (narrow tubes that carry urine from the kidneys to the bladder), the bladder, and the urethra are lined with these cells.
However, these three types of cancer can develop
anywhere in the urinary tract.
If abnormal cells are found anywhere in the urinary
tract, a search for other areas of abnormal cells is warranted. For example,
if cancerous cells are found in the bladder, an evaluation of the kidneys and
ureters is essential.
We do not know exactly what causes bladder cancer; however, a number of carcinogens have been identified that are potential causes, especially in cigarette smoke. Research is focusing on conditions that alter the genetic structure of cells, causing abnormal cell reproduction. We do know that the following factors increase a person's risk of developing a bladder cancer:
Smoking: Smoking is the single greatest risk factor for bladder cancer. Smokers have more than twice the risk of developing bladder cancer as nonsmokers.
Chemical exposures at work: People who regularly work with certain chemicals or in certain industries have a greater risk of bladder cancer than the general population. Organic chemicals called aromatic amines are particularly linked with bladder cancer. These chemicals are used in the dye industry. Other industries linked to bladder cancer include rubber and leather processing, textiles, hair coloring, paints, and printing. Strict workplace protections can prevent much of the exposure that is believed to cause cancer.
Diet: People whose diets include large amounts of fried meats and animal fats are thought to be at higher risk of bladder cancer.