A screening test that works the way it should and is helpful does the following:
Screening tests usually do not 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. More tests need to be done to find out if the lump is cancer. These are called diagnostic tests. Diagnostic tests may include a biopsy, in which cells or tissues are removed so a pathologist can check them under a microscope for signs of cancer.