Staging is the process of finding out how widespread the cancer is at the time it is found. The stage of a cancer is the most important factor in choosing among treatment options. The stage is based on whether the cancer is invasive or non-invasive, the size of the tumor, how many lymph nodes are involved, and whether it has spread to other parts of the body.

Tests to find breast cancer spread

One or more of the following tests may be done to help find out how much the cancer may have spread.

Chest x-ray: This test may be done to see whether the cancer has spread to the lungs.

Mammogram: If they haven't been done already, more mammograms may be done to get better pictures of the breasts.

Bone scan: This test can help show whether the cancer has spread to the bones. For this test, a very low dose of radioactive material is put into a vein. The bone attracts this material which shows up on the scan as a "hot spot." These hot spots could be cancer, but other problems, like arthritis can also cause them. Other tests or even biopsy samples of the hot spots may be needed.

CT scan (computed tomography): A CT scan is a special type of x-ray. Pictures are taken from different angles and these are combined by a computer to make a detailed picture of the organs. In women with breast cancer, this test is most often used to look at the chest and/or belly (abdomen) to see if the cancer has spread to other organs. It can also be used to guide a biopsy needle into an area of concern.

Before the CT scan, you may be asked to drink a contrast liquid to outline your intestines. After the first set of pictures is taken you may get an IV (intravenous) line through which a contrast dye is put into your blood. A second set of pictures is then taken.

The contrast may cause some flushing (a feeling of warmth, especially in the face). Some people are allergic and get hives. Rarely, more serious reactions like trouble breathing or low blood pressure can happen. Before you have this test be sure to tell your doctor if you have ever had a reaction to any contrast material used for x-rays.

CT scans take longer than regular x-rays. You need to lie still on a table while they are being done. You might feel a bit confined by the ring you have to lie in while the pictures are being taken.

MRI (magnetic resonance imaging): An MRI scan takes pictures using radio waves and strong magnets instead of x-rays. This test can be helpful in looking at the brain and spinal cord. MRIs can be a more uncomfortable than CT scans because they take longer and you need to lie in a narrow tube while the test is done. The machine also makes a loud, thumping noise that you may find disturbing. Some centers provide headphones with music to block out the noise.

Ultrasound: This test is described in the section "How is breast cancer found?" as an imaging test of the breast. But ultrasound can also used to look for cancer that has spread to some other parts of the body.

PET scan (positron emission tomography): This test uses a form of sugar that contains a radioactive atom. The sugar is put into a vein and travels throughout the body. Cancer cells absorb high amounts of this sugar. A special camera can then spot these cells. PET is useful when the doctor thinks the cancer has spread but doesn't know where. Some of the newer machines are able to do both a PET and CT scan at the same time.

The TNM staging system

The most common system used to describe the stages of breast cancer is the AJCC/TNM system. This system takes into account the tumor size and spread (T), whether the cancer has spread to lymph nodes (N), and whether it has spread to distant organs (M, for metastasis). Numbers after the T, N, and M give details about the cancer.

All of this information is combined in a process called stage grouping. The stage is then expressed as a Roman numeral. After stage 0 (carcinoma in situ), the other stages are I through IV (1-4). Some of the stages are further sub-divided using the letters A, B, and C. As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV (4), means a more advanced cancer. Cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

After looking at your test results, the doctor will tell you the stage of your cancer. Breast cancer staging can be complex. Be sure to ask your doctor to explain your stage in a way you understand. This will help you both decide on the best treatment for you.

Last Medical Review: 09/29/2009
Last Revised: 09/29/2009