The Test Sample
What is being tested?
Receptors are specialized proteins on the surface of or within cells that recognize and bind to other substances. The binding typically has a specific effect on the cells. Many, but not all, breast cancer cells have receptors that bind to the hormones estrogen and progesterone. Breast cancer tumors with estrogen receptors (ER) and progesterone receptors (PR) depend on the hormones to grow and divide. ER and PR testing of breast tumor tissue determines if one or both types of receptors are present.
Knowing if a tumor depends on hormones to grow helps a health practitioner determine a person's risk of breast cancer recurrence and whether it can be treated with hormone therapy to block estrogen and progesterone. About two-thirds of breast cancer tissues are positive for both ER and PR.
In 2010, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) jointly published guidelines that recommend that all tumors from individuals with newly diagnosed invasive breast cancer be evaluated for estrogen and progesterone receptors. The guidelines also state that all recurrent breast cancers should be tested and that the option of testing should be provided for patients who have non-invasive breast cancer.
How is the sample collected for testing?
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Your health practitioner may have you discontinue taking hormones for a time period before your sample is collected.