Breast Cancer: Tests You May Need
Laboratory tests involve testing blood, urine and/or other body fluids. They can be used as part of the diagnosis process, as well as to monitor your health during treatment. Here are some you may encounter or want to ask about:
Hormone receptor tests: These can be done using tissue from your initial biopsy and/or from your surgery to determine whether the hormones estrogen, progesterone or both are fueling your cancer’s growth.
HER2 (human epidermal growth factor receptor 2): This test determines whether your cancer cells have HER2 receptors on their surfaces, which means they grow rapidly when a specific protein latches onto them. A targeted treatment called Herceptin is now available for these cancers.
OncotypeDX™: This is a test that studies the activity of 21 genes within a tumor to find out if chemotherapy can be helpful, and to help gauge the likelihood that the cancer will return. It is specifically used for those with favorable prognostic factors (estrogen receptor positive and Her2 negative) and serves as a tool for determining whether you would benefit from chemotherapy or hormonal therapy.
Complete blood count (CBC): When you’re on chemo, getting a blood test called a CBC (complete blood count) becomes part of the routine. It’s usually done right before you get your chemo and then about two weeks later to make sure the chemo isn’t causing your blood cell levels (red blood cells, white blood cells and platelets) to fall out of a healthy range. If they do, your doctor can prescribe medication to help you stay on course. Other blood tests may look for:
- Magnesium levels. Magnesiumhelps muscle and nerve function, controls heartbeat, helps regulate blood pressure, controls blood sugar levels, keeps bones strong, regulates calcium levels and supports the immune system. Low levels of magnesium typically mean you're not consuming or absorbing enough, possibly due to your treatment.
- Calcium levels. Calcium helps with muscle contraction, nerve signaling and blood clotting and is essential for the development of strong bones and teeth. High levels of calcium, known as hypercalcemia, occur in 10% to 20% of adults with cancer, according to the National Cancer Institute. Symptoms often mimic the side effects of chemotherapy, including constipation, nausea, vomiting, fatigue, malaise and pain.
- Blood protein levels. Levels of various proteins in your blood (electrophoresis) can tell doctors the specific type of cancer you have.
- Tumor markers. Tumor markers are chemicals made by tumor cells that can be detected in your blood. But tumor markers are also produced by some normal cells in your body and levels may be significantly elevated in noncancerous conditions. This limits the potential for tumor marker tests to help in diagnosing cancer.
- Liver function. Cancer treatment may impair your liver’s ability to function. A blood test called a liver panel detects, evaluates and monitors liver disease or damage by measuring the blood levels of certain enzymes, proteins and other substances. Low or high levels may mean that the liver is damaged or diseased.