Cancer Screening Tests
Cancer screening tests help find cancer before a person has symptoms. Screening tests may find cancer early, and treatment is generally more effective on early stage cancer. Your medical provider may recommend screening for certain cancers depending on your cancer risk factors.
When doctors recommend cancer screening, it doesn’t always mean they think a person has cancer. Screening tests are preventative measures, especially if a person has risk factors. Risk factors include age, family history, genetics, lifestyle and exposure to carcinogens such as tobacco, asbestos or N-nitrosodimethylamine (NDMA).
Studies have shown that cancer screening tests can detect certain cancer types early and reduce the chance of dying from that cancer, according to the National Cancer Institute.
“Recommended cancer screening tests are very important to reducing the risk of diagnosis only after a cancer progresses, is more advanced, and less likely to be cured,” Dr. Gary Lyman, a professor in the Cancer Prevention Program at the Fred Hutchinson Cancer Research Center, told Drugwatch. “[Screening tests] are all indicated for certain individuals considered at higher risk due to age, family history or other risk factors. Recommended screening should not be ignored despite the [COVID-19] pandemic.”
The American Cancer Society says about 42 percent of cancer cases and 45 percent of cancer deaths in the United States are linked to potentially modifiable risk factors, and screening tests can prevent thousands of additional cancer cases and deaths.
While cancer screening can save lives, it’s not always recommended for everyone. Cancer screening does have potential harms, and the benefits don‘t always outweigh the risks for some people.
Potential Risks
The National Cancer Institute stresses that screening tests have harms as well as benefits. Patients should make sure to talk with their medical provider about whether the benefits of screening outweigh the risks.
- Bleeding or other health problems
- Radiation from repeated X-rays may cause cancer in healthy people
- False-positive results can cause anxiety and may require additional testing that also has potential harms
- False-negative results that provide false reassurance leading to delays in diagnosis
- Overdiagnosis leading to overtreatment of a cancer that may be slow growing and may not have harmed a person in their lifetime
Types of Cancer Screening Tests
Medical providers use a number of different tests to check for cancer. These include physical exams, laboratory tests, imaging tests and genetic tests.
“Two critical tests are screening mammography and colonoscopy, but there are others including PSA for prostate cancer and skin evaluation for individuals at risk for melanoma and other skin cancers, cervical screening for cervical cancer,” Lyman said.
The most common tests are designed to detect cancers of the breast, cervix, colon and lung. These tests are recommended by the U.S. Preventive Services Task Force and have been shown to reduce the risk of cancer deaths, according to the CDC.
Breast Cancer
Mammograms are X-rays of the breast and are the best way to detect breast cancer for most women. Women at high risk for breast cancer may have a mammogram along with a magnetic resonance imaging (MRI) of the breast.
In addition, a medical provider may use their hands to feel for lumps or other changes in the breasts.
Cervical Cancer
Pap tests and HPV tests are the two screening tests for cervical cancer. Both tests are done in the doctor’s office or clinic.
Using an instrument called a speculum, the medical provider will examine the cervix and vagina and collect cells and mucus samples from the cervix. These cells get sent to the lab and are tested for abnormal cells or the human papillomavirus, which can cause cervical cancer.
Colorectal or Colon Cancer
There are four different types of screening tests for colorectal cancer. They are designed to detect blood in the stool or polyps in the colon.
Talk to your medical provider about which test is right for you.
- Stool tests – patients provide a small sample of stool or an entire bowel movement to a lab. The lab checks for blood or altered DNA in the sample.
- Flexible sigmoidoscopy – doctors place a short, flexible, thin tube with a light into the rectum to check for polyps or cancer in the lower third of the colon and the rectum.
- Colonoscopy – doctors use a longer, flexible, lighted tube into the rectum and the entire colon to check for polyps and cancer. Polyps can be removed during the test.
- Virtual colonoscopy (CT Colonography) – doctors use X-rays and computers to produce images of the colon.
Lung Cancer
The only recommended screening test for lung cancer is low-dose computed tomography or CT scan. The test only takes a few minutes. Doctors use a low radiation X-ray to take images of the lungs.
Because of potential radiation problems from repeated CT scans, this test is only recommended for people who are at high risk of lung cancer.
Other Types of Cancer
Other types of cancers that have screening tests are ovarian, pancreatic, prostate, testicular, thyroid, bladder and skin cancer. The CDC hasn’t found evidence that screening for ovarian, pancreatic, prostate, testicular and thyroid cancer prevent deaths from these cancers.
There is insufficient evidence that the benefits of screening for bladder cancer, oral cancer and visual examination of the skin for skin cancer in adults without symptoms outweigh potential harms.
Screening Recommendations
The American Cancer Society provides recommendations for when people should get cancer screening tests. It released its most recent guidelines in Cancer Prevention & Early Detection Facts & Figures 2020.
If you are at high risk for certain cancers, your doctor may recommend a different screening schedule.
| Cancer | Recommendation |
|---|---|
| Breast | |
| Cervix | |
| Lung | Current or former smokers ages 55-74 in good health with 30+ pack-year histories who currently smoke or have quit within the past 15 years should discuss the risks and benefits of low-dose CT scans with their doctors. |
| Colorectal | Men and women 45 years or older can choose any of the following tests:
|
| Prostate |
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