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.
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.
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.
Screening tests have many goals.
A screening test that works the way it should and is helpful does the following:
Finds cancer before symptoms appear.
Screens for a cancer that is easier to treat and cure when found early.
Has few false-negative test results and false-positive test results.
Decreases the chance of dying from cancer.
Screening tests are not meant to diagnose cancer.
Screening tests usually do not diagnose cancer.
If a screening test result is abnormal, more tests may be done to check for cancer. For example, a screening mammogram may find a lump in the breast. A lump may be cancer or something else. More tests need to be done to find out if the lump is cancer. These are called diagnostic tests. Diagnostic tests may include a biopsy, in which cells or tissues are removed so a pathologist can check them under a microscope for signs of cancer.
Certain screening tests may be suggested only for people who have a high risk for certain cancers.
Anything that increases the chance of cancer is called a cancer risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Some screening tests are used only for people who have known risk factors for certain types of cancer. People known to have a higher risk of cancer than others include those who:
Have had cancer in the past; or
Have two or more first-degree relatives (a parent, brother, or sister) who have had cancer; or
Have certain gene mutations (changes) that have been linked to cancer.
People who have a high risk of cancer may need to be screened more often or at an earlier age than other people.