Bladder cancer

Bladder cancer

Fig.2.4.

Definition

Bladder cancer is a disease in which the cells lining the urinary bladder lose the ability to regulate their growth and start dividing uncontrollably. This abnormal growth results in a mass of cells that form a tumor. The most common type of bladder cancer diagnosed in the United States is urothelial bladder cancer, which in the past was classified as transitional cell carcinoma of the bladder.

(Fig 2.4.)
The urinary systems of a man and a woman, illustrating bladder cancer on the inner lining of the bladder.



Demographics

Bladder cancer is the fourth most commonly diagnosed cancer in men and the tenth most common cancer diagnosed in women in the United States. In 2009, the American Cancer Society (ACS) estimated that approximately 70,980 new cases of bladder cancer would be diagnosed (about 52,810 men and 18,170 women), causing approximately 14,330 deaths. The mortality rate for bladder cancer has declined since the 1990s. Greater than 90% of cases are diagnosed in individuals 55 years of age and older.



Description

The urinary bladder is a hollow muscular organ that stores urine from the kidneys until it is excreted out of the body. Two tubes called the ureters bring the urine from the kidneys to the bladder. The urethra carries the urine from the bladder to the outside of the body.

Bladder cancer has a very high rate of recurrence. Even after superficial tumors are completely removed, there is a 75% chance new tumors will develop in other areas of the bladder. Hence, patients need frequent and thorough follow-up care.

Risk factors

Smoking is considered the greatest risk factor for this type of cancer and by some estimates accounts for about 50% of all bladder cancers. Workers who are exposed to certain chemicals used in the dye industry and in the rubber, leather, textile, and paint industries are believed to be at a higher risk for bladder cancer. The disease also is three times more common in men than in women; Caucasians also are at an increased risk. The risk of bladder cancer increases with age. Most cases are found in people who are 50-70 years old.

Frequent urinary infections, kidney and bladder stones, and other conditions that cause long-term irritation to the bladder may increase the risk of getting bladder cancer. For example, individuals with spinal cord injuries requiring in-dwelling urinary catheters have a 16 to 20 times increased risk of developing bladder cancer. Apast history of tumors in the bladder also could increase one's risk of getting other tumors. Patients who have been previously treated with the cancer chemotherapy drug cyclophosphamide are at increased risk as are those who have been previously treated with radiation to the pelvis.

Several genetic mutations are associated with bladder cancer. Although heredity is not typically linked with the development of this type of cancer, familial clusters of bladder cancer have been identified.

Causes and symptoms

The exact cause of bladder cancer is not known, but smokers are twice as likely as nonsmokers to get the disease.

One of the first warning signals of bladder cancer is blood in the urine, which is reported by 80% of patients. This change in the urine is not typically associated with any pain. Sometimes, there is enough blood to change the color of the urine to a yellow-red or a dark red. At other times, the color of the urine appears normal but chemical testing of the urine reveals the presence of blood cells. Achange in bladder habits such as painful urination, increased frequency of urination and a feeling of needing to urinate but not being able to do so are some of the signs of possible bladder cancer. All of these symptoms may be caused by conditions other than cancer, but it is important to see a doctor and have the symptoms evaluated. When detected early and treated appropriately, patients have a very good chance of being cured completely.

Symptoms associated with advanced bladder cancer may include flank, back, and/or pelvic pain and edema in the lower extremities.

Examination

If a doctor has any reason to suspect bladder cancer, several tests can help find out if the disease is present. As a first step, a complete medical history will be taken to check for any risk factors. A thorough physical examination will be conducted to assess all the signs and symptoms.

Tests

Laboratory testing of a urine sample helps to rule out the presence of a bacterial infection. In a urine cytology test, the urine is examined under a microscope to look for any abnormal or cancerous cells.

Procedures

A catheter (tube) is sometimes advanced into the bladder through the urethra, and a salt solution is passed through it to wash the bladder. The solution is collected and examined under a microscope to check for the presence of cancerous cells.

Another procedure, known as the intravenous pyelogram (IVP), is an x-ray examination that is done after a dye is injected into the bloodstream through a vein in the arm. The dye travels through the bloodstream and then reaches the kidneys to be excreted. It clearly outlines the kidneys, ureters, bladder, and urethra. Multiple x rays are taken to detect any abnormality in the lining of these organs. In addition to the IVP, a renal ultrasound may be used in the diagnosis of bladder cancer.

A procedure known as a cystoscopy may be used to view the inside of the bladder. A thin, hollow, lighted tube is introduced into the bladder through the urethra. If any suspicious looking masses are seen, a small piece of the tissue can be removed from it using a pair of biopsy forceps. The tissue is then examined microscopically to verify if cancer is present, and if so, to identify the type of cancer.

If cancer is detected and there is evidence to indicate that it has metastasized (spread) to distant sites in the body, imaging tests such as chest x rays, computed tomography scans (CT), and magnetic resonance imaging (MRI) may be done to determine which organs are affected. Bladder cancer generally tends to spread to the lungs, liver, and bone.

Treatment

Treatment for bladder cancer depends on the stage of the tumor; specifically, whether the tumor has invaded the muscle wall of the bladder. The patient's medical history, overall health status, and personal preferences are taken into account when deciding on an appropriate treatment plan.

Traditional

Cystectomy, surgical removal of the bladder, may be used to treat cases of non-invasive and muscle-wall invasive cancers. In non-muscle invasive disease cystectomy may be performed if the tumor is an aggressive type that tends to recur despite treatment with BCG. A 90% survival rate can be attained in this group of patients if the cystectomy is done prior to progression of the tumor to the muscle wall. The 5-year survival rate after cystectomy drops by 30-40% once the muscle wall has been invaded by tumor. Surgery may also be recommended for patients with large superficial tumors that cannot be surgically removed, those with prostatic urethral involvement, and for patients who did not respond to BCG therapy.

In patients with muscle-invasive disease, surgery is done to remove the bladder, prostate, and pelvic lymph nodes in men. In women, the bladder, urethra, uterus, ovaries, anterior vaginal wall, and pelvic lymph nodes may be removed.

If the entire urinary bladder is removed, an alternate place must be created for the urine to be stored before it is excreted out of the body. To do this, a piece of intestine is converted into a small bag and attached to the ureters. This is then connected to an opening (stoma) that is made in the abdominal wall. The procedure is called a urostomy or a urinary diversion. In some urostomy procedures, the urine from the intestinal sac is routed into a bag that is placed over the stoma in the abdominal wall. The bag is hidden by the clothing and has to be emptied occasionally by the patient. In a different procedure, the urine is collected in the intestinal sac, but there is no bag on the outside of the abdomen. The intestinal sac has to be emptied by the patient, by placing a drainage tube through the stoma.

External beam radiation therapy as a primary therapy is not as effective as cystectomy in the treatment of bladder cancer. For disease confined to the bladder, the 5-year survival rate after cystectomy is 90% compared to a 5-year survival rate of 20-40% for patients treated with external beam radiation.

Prognosis

When detected in early stages, the prognosis for those with bladder cancer is excellent. At least 90% of people diagnosed with non-muscle invasive bladder cancer survive five years or more after initial diagnosis. However, if the disease has spread to the nearby tissues, the survival rate drops. Once the cancer hasmetastasized to distant organs such as the lung and liver, only 5% of patients survive two years or more. As newer treatment methods are developed, some prognoses improve.

Non-muscle invasive bladder cancers have a high rate of recurrence and progression. Careful follow-up and surveillance is of critical importance and includes cystoscopy and bladder wash cytology every three months for two years, then every six months for two years, followed by a minimum of once yearly.

Prevention

Since the exact causes of bladder cancer are not known, there is no certain way to prevent it. Avoiding risk factors whenever possible is the best alternative.

Since smoking doubles one's risk of getting bladder cancer, avoiding tobacco may prevent at least half the deaths that result from bladder cancer. Taking appropriate safety precautions when working with organic cancer-causing chemicals is another way of preventing the disease.

If a person has had a history of bladder cancer, or has been exposed to cancer-causing chemicals, he or she is considered to be at an increased risk of getting bladder cancer. Similarly, kidney stones, frequent urinary infections, and other conditions that cause longterm irritation to the bladder also increase the chance of getting the disease.