Testing For Cancer
The complete evaluation of a patient usually requires a thorough learning and physical examination along with diagnostic testing. Many tests are needed to determine whether a person has cancer, or if another condition (such as an infection) is mimicking the symptoms of cancer. Effective diagnostic testing is used to confirm or eliminate the presence of disease, monitor the disease process, and plan for and evaluate the effectiveness of treatment. In some cases, it is necessary to repeat testing. This may occur when a person’s condition has changed (if a sample collected was not of good quality), or an abnormal test result needs to be confirmed. Diagnostic procedures for cancer may include imaging, laboratory tests (including tests for tumor markers), tumor biopsy, endoscopic examination, surgery or genetic testing. Some of the more common procedures include:
- Biopsy: the removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on them.
- CAT scan: computerized axial tomography scan, also called a CT scan. A series of detailed pictures of areas inside the body, taken from different angles. The pictures are created by a computer linked to an x-ray machine.
- Excision: removal by surgery. An excisional biopsy is a surgical procedure in which an entire lump or suspicious area is removed for diagnosis. The tissue is then examined under a microscope.
- Magnetic resonance imaging (MRI): a test that uses powerful magnets and radio waves to construct pictures of the body.
- Positron emission tomography (PET): a nuclear scan that uses radioisotopes to create images from within the body, allowing physicians to evaluate organ function, localize disease or tumors and gauge response to therapies.
Screening tests are used to check for cancer in patients who may not have symptoms of cancer, but are at high risk for developing it. Early screening and detection has resulted in higher cure rates for many types of cancer.
Because some cancers are more common, doctors have been able to develop screening tests for them specifically. In addition to screening tests, genetic testing can determine whether an individual is predisposed to develop certain types of cancer.
Diagnostic tests are used in a number of ways to guide treatment, including determining diagnosis and prognosis and monitoring a cancer’s progression or recurrence. They may also be used to diagnose the primary disease and identify a cancer’s subtype, predict prognosis, direct treatment, evaluate a treatment’s effectiveness, detect residual disease and monitor remission or progression.
Diagnostic tests fall into five categories: pathology, diagnostic imaging, blood tests, tumor marker tests, and genomics.
Genetic tests—the examination of DNA for certain enzymes or proteins—are among the newest and most sophisticated methods of testing. Genetic testing helps to determine the likelihood of developing specific types of cancer, such as breast, colon, ovarian, prostate or endocrine cancer.
If you have a family history of any of these types of cancer, speak with your doctor about genetic testing.