Tuesday, January 24, 2012

Tests That Help Evaluate the Traits of Your Breast Cancer

Your doctor took a sample of cells from your breast using a biopsy to confirm that you have cancer.

If cancer is found, your doctor may request other tests to learn more about your specific type of cancer, its specific location, how far it has spread, and how fast it is growing. This will help determine which treatment is likely to be most effective for you. You may have one or more of the following tests.

Lab Tests

More lab tests may be done on the sample that was taken during your breast biopsy. From these tests your doctor will learn whether the tumor needs hormones to grow or has a special abnormality. Tumors that need hormones to grow are called hormone-receptor positive (HR+). In the case of breast cancer, the receptor that’s affected is the human epidermal growth factor receptor 2, or HER2. This helps determine how quickly the tumor might grow and guides the treatment plan.

Magnetic Resonance Imaging (MRI)

An MRI uses strong magnets and radio waves to produce pictures that are cross-sectional “slices” of your body from many different angles. Because of its sensitivity in finding breast abnormalities, an MRI is sometimes used to help decide whether just the lump should be taken out with a lumpectomy or if the whole breast should be removed with a mastectomy.

During an MRI of your breast, you’ll lie on your stomach on the scanning table. Your breast hangs into a hollowed-out part in the table. This area has coils that detect the magnetic signal given off by the MRI machine. The table is moved into a tubelike machine that contains the magnet. After a series of images have been taken, you may be given a contrast agent through a needle in your arm to help your doctor see the tumor. The contrast agent is not radioactive. More images are then taken. The entire session takes about one hour.

MRIs are also used to see if cancer has spread outside of the breast to the spine and brain. You lie still on a table inside a cylinder while the machine makes images of your spine and brain.

Computed Tomography (CT)

During a CT scan (also called a CAT scan), X-rays scan the entire chest in about 15 to 25 seconds. These X-rays are 100 times more sensitive than those of a typical X-ray. When you have breast cancer, these pictures help your doctor see where the cancer is located in your breast and whether it has spread to your lymph nodes, liver, or other organs. It can also be used to help guide the needle during a biopsy. To have the test, you lie still on a table as it gradually slides through the center of the CT scanner. Then the scanner rotates around you, directing a continuous beam of X-rays at your chest. A computer uses the data from the X-rays to create many pictures of your chest, which can be used together to create a three-dimensional picture. A CT scan is painless. You may be asked to hold your breath one or more times during the scan. In some cases, you will be asked to drink a contrast medium four to six hours before the scan. And you may be asked not to eat anything during the time between drinking the contrast and having the scan. The contrast will gradually pass through your system and leave your body through your bowel movements.

Bone Scan

This test shows whether cancer has spread to your bones. For this test, you’ll be injected with a small amount of radioactive substance. It travels through your bloodstream and collects in areas of abnormal bone growth. Any spots that show up may be caused by cancer, but things like arthritis or infection can also be the cause. The bone scan is the most sensitive technique currently available for identifying breast cancer that has spread to the bones.

Positron Emission Tomography (PET)

PET scans work differently from other imaging tests. They can actually measure body chemistry, making them helpful for evaluating small “hot spots” of cancer. They can help your doctor know where in the body the breast cancer has spread. Because this test scans your whole body, your doctor may order one instead of ordering multiple X-rays of different parts of your body. For this test, you get injected with sugar (glucose) that is carrying a mildly radioactive substance. Cancer cells are more active and absorb more of the sugar than healthy cells. Once the substance reaches your breast--on the same day as the injection--you’ll be asked to lie still on a table inside the PET scanner. It rotates around you, taking pictures of the glucose being used in your body. You’ll pass through the machine six or seven times. The entire scan takes about 45 minutes. A PET scan is painless. But if you’re sensitive to the sugar, you may have nausea, headache, or vomiting.