Some tests can help find cancer before signs or symptoms appear. This is called cancer screening.
The main goals of cancer screening are:
Reduce the number of people who die from the disease
Prevent cancer deaths altogether
Reduce the number of people who develop the disease
Which cancers have screening tests?
Some types of cancer have their own screening tests. Other types do not yet have an effective screening method. Developing new cancer screening tests is an area of active research.
Currently there are screenings for these types of cancer:
Breast cancer screening includes:
Clinical breast examination
Magnetic resonance images (MRI)
Mammography. Mammography is a type of x-ray specifically designed to view the breast. This screening test is also called a mammogram. The images produced during a mammogram can show tumors or other irregularities in the breast.
Clinical breast examination. During a clinical breast examination, a medical professional looks and feels for any changes in the breast’s size or shape. The examiner also looks for changes in the skin of the breasts and nipples.
Breast self-examination. Self-examination is a way to do a breast cancer screening at home. During a breast self-examination, you look and feel for changes in your own breasts. If you notice any changes, you should see a doctor.
MRI. An MRI is not regularly used to screen for breast cancer. But it may be helpful for those with a higher risk of breast cancer, those with dense breasts, or when a lump is found during a breast exam.
Screening for cervical cancer includes:
Human papillomavirus (HPV) test
HPV test. During an HPV test, the provider scrapes cells from the outside of the cervix. These cells are tested for specific strains of HPV. Some strains of HPV are more strongly linked to an increased risk of cervical cancer. This test may be done alone or combined with a pap test (see below).
Pap test. A pap test also uses cells from the outside the cervix. A pathologist then identifies any precancerous or cancerous cells. A pap test may be combined with HPV testing. It is sometimes called a pap smear.
There are several ways to screen for colorectal cancer, including:
Fecal occult blood test (FOBT)
Double contrast barium enema
Stool DNA tests
Colonoscopy. During a colonoscopy, the doctor inserts a flexible, lighted tube called a colonoscope into the rectum. The doctor is able to check the entire colon for polyps or cancer.
Sigmoidoscopy. For a sigmoidoscopy, the doctor uses a flexible, lighted tube called a sigmoidoscope to check the lower colon for polyps and cancer. The doctor cannot check the upper part of the colon with this test.
Fecal occult blood test (FOBT). An FOBT finds small amounts of blood in the feces, or stool, which can be a sign of polyps or cancer. There are two types of FOBTs: guaiac and immunochemical.
Double contrast barium enema. A double contrast barium enema is an x-ray of the colon and rectum. The barium enema helps the outline of the colon and rectum stand out on the x-rays. Doctors use this test to screen people who cannot have a colonoscopy.
Stool DNA tests. Stool DNA tests analyze DNA from a person’s stool sample to look for cancer. It uses DNA changes found in polyps and cancers to help a doctor decide if a colonoscopy is needed.
Screening for head and neck cancers is part of a general checkup. The doctor looks in the nose, mouth, and throat for abnormalities and feels for lumps in the neck.
Regular dental check-ups are also important to screen for head and neck cancers. Dental hygienists and dentists can check for signs of oral cancer on your tongue, cheek, throat, or lips.
To screen for lung cancer, doctors use a low-dose helical or spiral computed tomography (CT or CAT) scan. A CT scan takes x-rays of the inside of the body from different angles. A computer then combines these images into a detailed, 3-dimensional image that shows any abnormalities or tumors.
There are two tests to screen for prostate cancer:
Digital rectal exam (DRE)
Prostate-specific antigen (PSA) test
Digital rectal exam (DRE). A DRE is a test in which the doctor inserts a gloved, lubricated finger into your rectum and feels the surface of the prostate for any irregularities.
Prostate-specific antigen (PSA) test. A PSA test is blood test measures the level of a substance called PSA. PSA is usually found at higher-than-normal levels in patients with prostate cancer. But a high PSA level may also be a sign of other conditions that are not cancerous.
The screening tests for skin cancer include:
Full body skin exam
Full body skin exam. A dermatologist or other health care provider can screen for skin cancer as part of a full body skin exam. A doctor checks the skin for signs of skin cancer.
Dermoscopy. Dermatologists might use a handheld device called a dermatoscope to evaluate the size, shape, and pigmentation patterns of skin lesions. Dermoscopy is usually used for the early detection of melanoma.
Skin self-examination. You can also examine your entire body in a mirror for signs of skin cancer. This is called a self-exam. It often helps to have another person check places you can't see easily on your own body, such as your scalp, your back, and the back of your neck.
What are the risks of cancer screening?
Screening tests can help doctors find a cancer at an earlier, more treatable stage. This may help improve survival. But cancer screening also has a number of risks that it is best to understand before getting screened. These risks include:
False positives. Sometimes a screening test will suggest that a person has cancer when they do not. This is called "false positive" and it can cause anxiety and stress.
Overdiagnosis. Screening tests may find slow-growing cancers that would not have caused any harm during a person's lifetime. As a result, some people may receive potentially harmful, painful, stressful, and/or expensive treatments that they did not need.
Increased testing. Doctors may run additional tests that a person may not need because of false positives and overdiagnoses. These tests can be physically invasive, costly, and can cause unnecessary stress and worry.
False reassurance. Sometimes a screening test will suggest a person does not have cancer when they actually do. This may be called false negative. As a result, a person may not get the treatment they need.
What are screening recommendations
A number of organizations provide guidelines on specific cancer screening tests for specific types of cancer. (See the links above explain different guidelines for the types of cancer reviewed in this article.) Sometimes these guidelines suggest different things. Recommendations vary on:
Who should be screened for which type of cancer
Which specific test(s) should be used to screen for a particular type of cancer
What age screening should begin and end
How often screening tests should be done
What happens next if the screening test shows positive results
Talk with your doctor about your personal risk of developing cancer. Together you and your doctor can decide on an appropriate screening schedule based on your age and personal and family medical history.
Questions to ask the health care team
What types of cancer am I at risk for?
What types of cancer screening should I receive?
When should I start getting cancer screenings? And how often?
Are there exams I can or should do at home?
What are the risks of this cancer screening test?
Can we talk about the test's potential risks compared to its benefits?
If this test indicates cancer, what is the next step?