What is the difference between a screening test and a diagnosis?

A screening test and a diagnosis are not the same thing. Screening tests are done to look for cancer before a person has any symptoms. They are not meant to 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, so more tests are needed to find out. These are called diagnostic tests, and they may include a biopsy, in which cells or tissues are removed so a pathologist can check them under a microscope for signs of cancer.

So a screening test raises a question, while diagnostic tests help answer it. Your healthcare team can explain what any result means and what the next steps would be.