Bladder cancer is the 4th most common cancer in men & 8th most
common cancer in women. It is more common in men than in women, and more
common in whites than in African Americans. The American Cancer Society
estimates that in the year 2007 there were about 50,000 men &
17,000 women with newly diagnosed with bladder cancer & 14,000
deaths as a result of it. The cancer is generally limited to the inside
lining of the bladder in cases detected early but can extend into the
muscular layer if there is a delay in diagnosis which can result in a
poorer prognosis. There are 3 types of bladder cancer. They are
Transitional cell carcinoma, Squamous cell carcinoma &
Adenocarcinoma. In the U.S. Transitional cell carcinoma is the most
frequently encountered.
Screening for bladder cancer is done on at
risk population who are yet to show any signs of the disease & is at
an early stage with a greater chance for a cure or a better life
expectancy.
Risk factors for bladder cancer are smoking, old age,
workplace exposure to certain chemicals ( rubber, leather, paints, dyes,
metals or petroleum products), family history of bladder cancer,
schistosomiasis (a parasitic infection of the bladder), chronically
inflamed bladder, previous radiation exposure to the pelvic region ( due
to treatment of other cancers), taking of certain anticancer drugs,
long term use of urinary catheters, drinking water that has high levels
of arsenic or chlorine etc.
Bladder cancer can be without any
symptoms or have symptoms like having increased frequency of voiding
(urinary frequency), pain during voiding (dysuria), cloudy urine,
recurrent urinary tract infections or blood in the urine (hematuria).
If
screening tests are found to be abnormal, then further tests called
diagnostic tests are needed to confirm the existence of bladder cancer.
The following tests are currently used to screen for bladder cancer.
Cystoscopy
In
Cystoscopy a thin instrument with a light & lens for viewing at its
end is inserted through the urethra & into the bladder. The bladder
is then filled with a transparent fluid after which the operator is
able to visualize the inside portion of the bladder. Any abnormality on
the walls of the bladder is noted & samples of tissue can be taken
forbiopsy. It is normally done under a local anesthetic.
Urine cytology
In
this test a sample of urine is checked under a microscope for abnormal
looking cancerous cells. However absence of such cells does not rule out
bladder cancer. Further tests are usually needed to confirm or rule out
the diagnosis if symptoms are suggestive of bladder cancer.
Microscopic Urinalysis for hematuria
Hematuria
or the presence of red blood cells in the urine may be caused by
bladder cancer or by some other conditions. It is done by viewing a
urine sample under a microscope or using a special test strip called
dipsticks.
Urine biomarkers for bladder cancer
These
are chemicals, proteins and chromosomal changes found in the urine of
patients which are used to detect bladder cancer. They are thought to be
made by bladder cancer cells. They include UroVysion test, ImmunoCyt
test and NMP-22 test. At present these tests are not done on a routine
basis but their use is increasing.
False-positive & False-negative test results:
Screening
test results can appear to be abnormal even though no cancer is
present. This is called a false-positive test result. It can cause
anxiety to the patient & his or her family and requires further
invasive procedures which are unnecessary & have risks.
Alternatively screening test results can appear to be normal even though
bladder cancer is present. This is called a false negative test result.
This can lead to costly delay in seeking appropriate medical care.
It
has yet to be proved that the use of screening tests for bladder cancer
will decrease the risk of dying from it. Screening for bladder cancer
is still under study and there are ongoing clinical trials taking place.