What Is Cancer?

Cancer is a disease that occurs when cells grow uncontrollably and spread to other areas in your body. It can start almost anywhere, and there are more than 100 different types of cancer, most of which are named for the organ or tissue where the disease began.

  • Cancer is caused by damaged cells growing and multiplying when they shouldn’t.
  • Around 1.9 million new cancer cases occur each year in the U.S.
  • Approximately 39.5% of adults will be diagnosed with cancer at some point in their lifetime.

The Role of Cancer Tests

Cancer tests can be used to diagnose, screen for, and monitor cancer.

  • Diagnosis: Cancer diagnosis tests can indicate the type of cancer you may have, which can guide your treatment options. This type of test can also rule out cancer.
  • Screening: Cancer screening tests are used to check your body for the presence of disease before you have symptoms. Screening can help identify cancers early, when treatment is the most likely to work well.
  • Monitoring: As cancer progresses or you go into remission, monitoring tests can guide your health care team to determine treatment success or cancer recurrence.

Who should get testing?

Your doctor may order cancer diagnosis testing based on symptoms or a cancer screening test result that suggests cancer. If you have cancer, your health care team may use cancer monitoring tests to monitor cancer growth during and after treatment, oftentimes using specific tumor markers.

Cancer screening tests are most often recommended for people who are considered at high risk. You’re considered to be at higher risk for developing cancer if you have any of the following:

  • A personal history of cancer
  • A family history of cancer
  • Gene mutations linked to cancer
  • Past exposure to cancer-causing agents such as workplace chemicals or tobacco
  • A blood clot that developed for no known reason
  • Older age

If you have a high risk of cancer, it is important to be screened more often or at an earlier age than the general population.

People who are not at high risk should still get cancer screening at various points in their lives. There are cancer screening guidelines based on age:

  • Ages 25 to 30: 
    • Cervical cancer screening for people with a cervix
  • Ages 40 to 29: 
    • Breast cancer screening begins at age 40 or 45
    • Cervical cancer screening for people with a cervix
    • Colorectal cancer screening begins at age 45
    • Prostate cancer screening for African Americans starts at age 45
  • Ages 50+:
    • Breast cancer screening
    • Cervical cancer screening
    • Colorectal cancer screening
    • Lung cancer screening for people who currently smoke or formerly smoked
    • Prostate cancer screening

More Cancer Tests

Getting Cancer Tests

Your doctor will tell you if they think you need a cancer test, where you can get one, and how to schedule it. While cancer screening tests are done before you have any symptoms, cancer diagnosis and monitoring tests are performed when it’s suspected you have cancer or you’re going through cancer treatment.

Before prescribing a test, your doctor may review your and your family’s medical history as well as your health habits to determine if you are at high risk of developing a certain type of cancer. They will then be able to determine which tests are most appropriate for you.

If you don’t have a doctor, you may be able to find a local community facility that performs screenings without a doctor’s order. For instance, some local health departments have facilities that perform mammograms. There are currently no home blood tests for cancer.

Costs of cancer testing

The cost of cancer tests will vary by location and test type. Some clinics, usually community or nonprofit clinics, offer free or low-cost screening for certain types of cancers for people without health insurance. Some hospitals may also host free cancer screening events.

Some cancer tests, like colorectal cancer screening, can be done at home while others require a visit to a lab or doctor’s office. Your actual cost depends on the type of test performed, the lab, and your insurance coverage.

Types of sample collection

The sample for a cancer test will depend on the particular test you’re taking. Tissue, blood, urine, stool, or visual imaging are the most common specimens used.

Getting test results

Patients may receive results of cancer tests during a follow-up appointment with their doctor, over the phone, or through online medical charts. It’s important to discuss test results with a health care professional who can help you manage your risk for cancer and answer your questions about test results.


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