How Cancer Is Diagnosed

Male Doctor Talking with an Elderly Female Patient About a Digital Image

X-rays use low doses of radiation to create pictures of the inside of your body.

Credit: iStock

If you have a symptom or your screening test result suggests cancer, the doctor must find out whether it is due to cancer or some other cause. The doctor may ask about your personal and family medical history and do a physical exam. The doctor also may order lab tests, scans, or other tests or procedures.

Lab Tests

High or low levels of certain substances in your body can be a sign of cancer. So, lab tests of the blood, urine, or other body fluids that measure these substances can help doctors make a diagnosis. However, abnormal lab results are not a sure sign of cancer. Lab tests are an important tool, but doctors cannot rely on them alone to diagnose cancer.

Imaging Procedures

Imaging procedures create pictures of areas inside your body that help the doctor see whether a tumor is present. These pictures can be made in several ways:

Biopsy

In most cases, doctors need to do a biopsy to make a diagnosis of cancer. A biopsy is a procedure in which the doctor removes a sample of tissue. A pathologist  then looks at the tissue under a microscope to see if it is cancer. The sample may be removed in several ways: