Cancer Screening

Cancer screening is looking for cancer before a person has any symptoms.

Screening tests can help find cancer at an early stage, before symptoms appear. When abnormal
tissue or cancer is found early, it may be easier to treat or cure. By the time symptoms appear,
the cancer may have grown and spread. This can make the cancer harder to treat or cure.

It is important to remember that when your doctor suggests a screening test, it does not always
mean he or she thinks you have cancer. Screening tests are done when you have no cancer
symptoms.

There are different kinds of screening tests.

Screening tests include the following:

• Physical exam and history: An exam of the body to check general signs of health,
including checking for signs of disease, such as lumps or anything else that seems
unusual. A history of the patient’s health habits and past illnesses and treatments will also
be taken.
• Laboratory tests: Medical procedures that test samples of tissue, blood, urine, or other
substances in the body.
• Imaging procedures: Procedures that make pictures of areas inside the body.
• Genetic tests: Tests that look for certain gene mutations (changes) that are linked to some
types of cancer.

Screening tests have risks.

Not all screening tests are helpful and most have risks. It is important to know the risks of the
test and whether it has been proven to decrease the chance of dying from cancer.

Some screening tests can cause serious problems.

Some screening procedures can cause bleeding or other problems. For example, colon cancer
screening with sigmoidoscopy or colonoscopy can cause tears in the lining of the colon.

False-positive test results are possible.

Screening test results may appear to be abnormal even though there is no cancer. A false-positive
test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually
followed by more tests and procedures, which also have risks.

False-negative test results are possible.

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Screening test results may appear to be normal even though there is cancer. A person who
receives a false-negative test result (one that shows there is no cancer when there really is) may
delay seeking medical care even if there are symptoms.

Finding the cancer may not improve the person's health or help the person live longer.

Some cancers never cause symptoms or become life-threatening, but if found by a screening test,
the cancer may be treated. There is no way to know if treating the cancer would help the person
live longer than if no treatment were given. In both teenagers and adults, there is an increased
risk of suicide in the first year after being diagnosed with cancer. Also, treatments for cancer
have side effects.

For some cancers, finding and treating the cancer early does not improve the chance of a cure or
help the person live longer.

What your doctor is looking for

Samples collected for cancer blood tests are analyzed in a lab for signs of cancer. The samples
may show cancer cells, proteins or other substances made by the cancer. Blood tests can also
give your doctor an idea of how well your organs are functioning and if they've been affected by
cancer.

Examples of blood tests used to diagnose cancer include:

• Complete blood count (CBC). This common blood test measures the amount of various
types of blood cells in a sample of your blood. Blood cancers may be detected using this
test if too many or too few of a type of blood cell or abnormal cells are found. A bone
marrow biopsy may help confirm a diagnosis of a blood cancer.
• Blood protein testing. A test to examine various proteins in your blood (electrophoresis)
can aid in detecting certain abnormal immune system proteins (immunoglobulins) that
are sometimes elevated in people with multiple myeloma. Other tests, such as a bone
marrow biopsy, are used to confirm a suspected diagnosis.
• Tumor marker tests. Tumor markers are chemicals made by tumor cells that can be
detected in your blood. But tumor markers are also produced by some normal cells in
your body, and levels may be significantly elevated in noncancerous conditions. This
limits the potential for tumor marker tests to help in diagnosing cancer.

Examples of tumor markers include prostate-specific antigen (PSA) for prostate cancer,
cancer antigen 125 (CA 125) for ovarian cancer, calcitonin for medullary thyroid cancer,
alpha-fetoprotein (AFP) for liver cancer and human chorionic gonadotropin (HCG) for
germ cell tumors, such as testicular cancer and ovarian cancer.

• Circulating tumor cell tests. Experimental blood tests are being developed to find cells
that have broken away from an original cancer site and are floating in the bloodstream.

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 More research is needed to understand how these tests can help doctors diagnose
advanced cancers.

Screening Tests

Many cancer screening tests are in use. Some tests have been shown both to find cancer early
and to lower the chance of dying from the disease. Others have been shown to find cancer early
but have not been shown to reduce the risk of dying from cancer; however, they may still be
offered to people, especially those who are known to be at increased risk of cancer.

Screening Tests That Have Been Shown to Reduce Cancer

Deaths
• Colonoscopy, sigmoidoscopy, and high-sensitivity fecal occult blood tests (FOBTs)
These tests have all been shown to reduce deaths from colorectal cancer. Colonoscopy
and sigmoidoscopy also help prevent colorectal cancer because they can detect abnormal
colon growths (polyps) that can be removed before they develop into cancer. Expert
groups generally recommend that people who are at average risk for colorectal cancer
have screening at ages 50 through 75.
• Low-dose helical computed tomography
This test to screen for lung cancer has been shown to reduce lung cancer deaths among
heavy smokers ages 55 to 74.
• Mammography
This method to screen for breast cancer has been shown to reduce mortality from the
disease among women ages 40 to 74, especially those age 50 or older
• Pap test and human papillomavirus (HPV) testing
These tests reduce the incidence of cervical cancer because they allow abnormal cells to
be identified and treated before they become cancer. They also reduce deaths from
cervical cancer. Testing is generally recommended to begin at age 21 and to end at age
65, as long as recent results have been normal..

Other Screening Tests

• Alpha-fetoprotein blood test
This test is sometimes used, along with ultrasound of the liver, to try to detect liver
cancer early in people at high risk of the disease.
• Breast MRI
This imaging test is often used for women who carry a harmful mutation in the BRCA1
gene or the BRCA2 gene; such women have a high risk of breast cancer, as well as
increased risk for other cancers.

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• CA-125 test
This blood test, which is often done together with a transvaginal ultrasound, may be used
to try to detect ovarian cancer early, especially in women with an increased risk of the
disease. Although this test can help in diagnosing ovarian cancer in women who have
symptoms and can be used to evaluate the recurrence of cancer in women previously
diagnosed with the disease, it has not been shown to be an effective ovarian cancer
screening test.
• Routine examination of the breasts by health care providers or by women themselves has
not been shown to reduce deaths from breast cancer. However, if a woman or her health
care provider notices a lump or other unusual change in the breast, it is important to get it
checked out
• PSA test- prostate- specific antigen
This blood test, which is often done along with a digital rectal exam, is able to detect
prostate cancer at an early stage. However, expert groups no longer recommend routine
PSA testing for most men because studies have shown that it has little or no effect on
prostate cancer deaths and leads to overdiagnosis and overtreatment.
• Skin exams
Doctors often recommend that people who are at risk for skin cancer examine their skin
regularly or have a health care provider do so. Such exams have not been shown to
decrease the risk of dying from skin cancer, and they may lead to overtreatment.
However, people should be aware of changes in their skin, such as a new mole or a
change to an existing mole, and report these to their doctor promptly.
• Transvaginal ultrasound
This imaging test, which can create pictures of a woman’s ovaries and uterus, is
sometimes used in women who are at increased risk of ovarian cancer (because they carry
a harmful BRCA1 or BRCA2 mutation) or of endometrial cancer (because they have a
condition called Lynch syndrome). But it has not been shown to reduce deaths from
either cancer..
• Virtual colonoscopy
This test allows the colon and rectum to be examined from outside the body. However, it
has not been shown to reduce deaths from colorectal cancer.

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