Section 11. Kidney and Urinary Tract Disorders

Chapter 151. Cancers of the Kidney and Urinary Tract

Topics: Introduction | Kidney Cancer | Cancers of the Renal Pelvis and Ureter | Bladder Cancer | Cancer of the Urethra

Bladder Cancer

An estimated 54,300 new cases of bladder cancer are diagnosed every year in the United States. About 2 ½ times as many men as women develop bladder cancer. Smoking is the strongest single risk factor and appears to be one of the underlying causes in at least half of all new cases. Certain chemicals that are used in industry can become concentrated in the urine and cause cancer, although exposure to these chemicals is decreasing. The chronic irritation that occurs with a parasitic infection called schistosomiasis or with bladder stones also predisposes people to bladder cancer, although irritation accounts for only a small proportion of all cases.

Most cases of bladder cancer are of transitional cells (called transitional cell carcinoma of the bladder), the same type of cells that line the renal pelvis and ureters.

Symptoms and Diagnosis

Bladder cancer is often first suspected when blood is found in the urine. Blood may be detected when a routine microscopic examination of a urine specimen detects red blood cells. However, the urine may be visibly red. Later symptoms may include pain and burning during urination and an urgent, frequent need to urinate. The symptoms of bladder cancer may be identical to those of a bladder infection (cystitis (see Section 11, Chapter 149)), and the two problems may occur together. Bladder cancer may be suspected if the symptoms do not disappear with treatment for the cystitis. Special microscopic evaluation of urine (cytology (see Section 11, Chapter 142)) frequently detects cancer cells.

Cystography or intravenous urography--x-ray films taken after a radiopaque dye is injected intravenously--may show an irregularity in the bladder wall, suggesting a possible cancer. Ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) may also show an abnormality in the bladder, usually by chance during evaluation of another problem. If any of these tests detect a growth, the doctor looks inside the bladder with a cystoscope passed through the urethra and removes samples of any suspicious areas for examination under a microscope (biopsy).

Prognosis

For superficial tumors that grow and divide slowly, the risk of death from bladder cancer is less than 5%, but the risk may rise to about 15 to 20% for tumors that grow and divide rapidly or that have invaded almost as far as the muscle layer of the bladder. The 5-year survival rate for tumors that invaded the superficial layer of muscle is a little worse, with the risk of death probably rising to 20 to 35%; some of these people may benefit from chemotherapy. For tumors extending into or through the deep muscle layer, the 5-year survival rate is 45 to 60%. If the cancer has spread to the lymph nodes or beyond, the 5-year survival rate is 20 to 45%.

Treatment

Cancers that remain on the bladder's inner surface or invade only the most superficial part of the muscle layer under the surface may be removed completely during cystoscopy. However, people commonly develop new cancers later, sometimes in the same place or, more commonly, elsewhere in the bladder. Doctors may be able to prevent the recurrence of cancers that are limited to the inner surface of the bladder by repeatedly instilling anticancer drugs or BCG (a substance that stimulates the body's immune system) into the bladder after all of the cancer has been removed during cystoscopy. These instillations may serve as treatment for people with cancers that cannot be removed during cystoscopy.

Cancers that have grown deep into or through the bladder wall cannot be completely removed through a cystoscope. They are usually treated by total or partial removal of the bladder (cystectomy). Radiation therapy alone or in combination with chemotherapy may also be used in an attempt to cure the cancer.

If the entire bladder needs to be removed, the doctor must devise a method for the person to be able to drain urine. Usually, urine is routed to an opening (stoma) made in the abdominal wall through a passageway made of intestine, called an ileal loop. The urine is then collected in a bag worn on the outside of the body.

Several alternative methods of diverting urine are becoming increasingly common and are appropriate for some people. These methods can be grouped into two categories: an orthotopic neobladder and a continent urinary diversion. In both, an internal reservoir for urine is constructed from the intestine.

For an orthotopic neobladder, the reservoir is connected to the urethra. The person learns to empty this reservoir by relaxing the pelvic floor muscles and increasing pressure within the abdomen, so that urine passes through the urethra very much as it would naturally. Most people are dry during the day, but some incontinence may occur at night.

For a continent urinary diversion, the reservoir is connected to a stoma in the abdominal wall. A collecting bag is not needed, because the urine remains in the reservoir until the person empties it by inserting a catheter through the stoma into the reservoir, which is emptied at regular intervals throughout the day.

Cancer that has spread beyond the bladder to the lymph nodes or other organs is treated with chemotherapy. Several different combinations of drugs are active against this type of cancer, particularly when the spread is confined to the lymph nodes. Cystectomy or radiation may be offered to people who respond well to chemotherapy. However, a relatively small number of people are cured. For people who are not cured, efforts are directed at pain relief and end-of-life issues (see Section 1, Chapter 8).