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Overview
The bladder is an organ located
in the pelvic cavity that stores and discharges
urine. Urine is produced by the kidneys, carried
to the bladder by the ureters, and discharged from
the bladder through the urethra. Bladder cancer
accounts for approximately 90% of cancers of the
urinary tract (renal pelvis, ureters, bladder,
urethra).
Types
Bladder cancer usually originates in the bladder
lining, which consists of a mucous layer of
transitional epithelial cells (surface cells that
expand and deflate), smooth muscle, and a fibrous
layer. The tumor is categorized as low stage
(superficial) or high stage (muscle invasive).
In industrialized countries
(e.g., United States, Canada, France), more than
90% of cases originate in the transitional
epithelial cells (called transitional cell
carcinoma; TCC). In developing countries, 75%
of cases are squamous cell carcinomas caused by
Schistosoma haematobium (parasitic organism)
infection. Rare types of bladder cancer include
small cell carcinoma, carcinosarcoma, primary
lymphoma, and sarcoma.
Incidence and Prevalence
The incidence of bladder cancer is highest in
industrialized countries and lowest in Asia and
South America. Bladder cancer is about 3 times
more common in men. It is the fourth most common
cancer in men and the eighth most common in women.
The average age at diagnosis is 65 and prevalence
increases with age.
Causes and
Risk Factors
Cancer-causing agents
(carcinogens) in the urine may lead to the
development of bladder cancer. Cigarette
smoking contributes to more that 50% of cases,
and smoking cigars or pipes also increases the
risk. Other risk factors include the following:
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Age
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Caucasian
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Chronic bladder inflammation
(recurrent urinary tract infections, urinary
stones)
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Consumption of Aristolochia
fangchi (herb used in some weight-loss
formulas)
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Diet high in saturated fat
-
Exposure to second-hand smoke
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External beam radiation
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Family history of bladder cancer
(several genetic risk factors identified)
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Infection with Schistosoma
haematobium (parasite found in many
developing countries)
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Male
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Personal history of bladder
cancer
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Treatment with certain drugs
(e.g. cyclophosfamide—used to treat cancer)
Exposure to carcinogens in the
workplace also increases the risk for bladder
cancer. Medical workers exposed during the
preparation, storage, administration, or disposal
of antineoplastic drugs (used in chemotherapy) are
at increased risk. Occupational risk factors
include recurrent and early exposure to hair dye,
and exposure to dye containing aniline, a chemical
used in medical and industrial dyes. Other workers
at increased risk include the following:
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Hairdressers
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Machinists
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Printers
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Painters
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Truck drivers
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Workers in rubber, chemical,
textile, metal, and leather industries
Signs and Symptoms
The primary symptom of bladder
cancer is blood in the urine (hematuria).
Hematuria may be gross (visible to the naked eye)
or microscopic (visible only under a microscope)
and is usually painless. Other symptoms include
frequent urination and pain upon urination (dysuria).
Diagnosis
Diagnosis of bladder cancer
includes urological tests and imaging tests. A
complete medical history is used to identify
potential risk factors (e.g., smoking, exposure to
dyes). Laboratory tests may include the following:
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Urinalysis (to detect microscopic
hematuria)
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Urine cytology (to detect cancer
cells by examining cells flushed from the
bladder during urination)
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Urine culture (to rule out
urinary tract infection)
Various imaging tests may
also be performed. Intravenous pyelogram (IVP) is
the standard imaging test for bladder cancer. In
this procedure, a contrast agent (radiopaque dye)
is administered intravenously and x-rays are taken
as the dye moves through the urinary tract. IVP
provides information about the structure and
function of the kidneys, ureters, and bladder.
Other imaging tests include CT scan, MRI scan,
bone scan, and ultrasound.
If bladder cancer is suspected,
cystoscopy and biopsy are performed.
Local anesthesia is administered and a cystoscope
(thin, telescope-like tube with a tiny camera
attached) is inserted into the bladder through the
urethra to allow the physician to detect
abnormalities. In biopsy, tissue samples are taken
from the lesion(s) and examined for cancer cells.
If the sample is positive, the cancer is staged
using the tumor, node, metastases (TNM)
system.
Treatment
Treatment for bladder cancer
depends on the stage of the disease, the type of
cancer, and the patient’s age and overall health.
Options include surgery, chemotherapy, radiation,
and immunotherapy. Treatments are sometimes
combined (e.g., surgery or radiation and
chemotherapy).
Surgery
The type of surgery depends on the stage of the
disease. In early bladder cancer, the tumor may be
resected (removed) using instruments inserted
through the urethra (transurethral resection).
In advanced stages of the
disease, partial or radical cystectomy
(removal of the bladder) is performed. Radical
cystectomy includes removal of nearby lymph nodes.
In men, the prostate gland is also removed. In
women, the uterus, ovaries, fallopian tubes, and a
section of the vagina may be removed as well.
Radical cystectomy requires a
urostomy or a continent diversion for the
storage and removal of urine. Complications
include infection, urinary stones, and urine
blockages.
Immunotherapy
Immunotherapy, also called biological therapy, is
used to enhance the immune system’s ability to
fight cancer. In this treatment, BCG, a vaccine
derived from the bacteria that causes
tuberculosis, is infused through the urethra into
the bladder, once a week for 6 weeks. This vaccine
stimulates the immune system to destroy cancer
cells and is used in early bladder cancer that is
superficial. Sometimes BCG is used with
interferon.
Side effects
include inflammation of the bladder (cystitis),
inflammation of the prostate (prostatitis), and
flu-like symptoms. If high fever (over 101.5 °F)
occurs, it may indicate that the bacteria have
entered the bloodstream (i.e., bacteremia), a
life-threatening condition that requires
antibiotic treatment. Immunotherapy is not used in
patients with gross hematuria.
Chemotherapy
Chemotherapy is the use of drugs to destroy cancer
cells. It is a systemic treatment (i.e., destroys
cancer cells throughout the body) and is
administered orally or intravenously (through a
vein). In early bladder cancer, intravesical
chemotherapy (infused into the bladder through the
urethra) may be recommended. Chemotherapy may be
adjuvant (after surgery), or neoadjuvant (before
surgery) therapy.
Drugs used in the treatment of
bladder cancer include valrubicin (Valstar™),
thiotepa (Thioplex®), mitomycin, and doxorubicin (Rubex®).
Side effects can be severe and include the
following:
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Abdominal pain
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Anemia (causes weakness, fatigue)
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Bladder irritation
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Blurred vision
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Excessive bleeding or bruising
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Headache
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Infection
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Loss of appetite (anorexia)
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Nausea and vomiting
Radiation
Radiation uses high-energy rays to destroy cancer
cells. External beam radiation is emitted from a
machine outside the body and internal radiation is
emitted from radioactive "seeds" implanted into
the tumor. Either type of radiation therapy may be
used after surgery to destroy cancer cells that
may remain. Radiation therapy is also used to ease
symptoms in advanced cases of bladder cancer. Side
effects include inflammation of the rectum (proctitis),
incontinence, skin irritation, hematuria, fibrosis
(buildup of fibrous tissue), and impotence.
Photodynamic therapy is a new
treatment for early bladder cancer. It involves
administering drugs to make cancer cells more
sensitive to light and then shining a special
light onto the bladder. This treatment is being
studied in clinical trials.
Follow-Up
Bladder cancer has a high rate of recurrence.
Urine cytology and cystoscopy are performed every
3 months for 2 years, every 6 months for the next
2 years, and then yearly.
Prognosis
Superficial bladder cancer has a
5-year survival rate of about 85%. Invasive
bladder cancer has a less favorable prognosis.
Approximately 5% of patients with metastasized
bladder cancer live 2 years after diagnosis. Cases
of recurrent bladder cancer indicate an aggressive
tumor and a poor prognosis.
Prevention
Bladder cancer cannot be
prevented. The best way to lower the risk is not
to smoke. Studies have shown that drinking plenty
of fluids daily also lowers the risk for bladder
cancer.
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