After discovering that you have breast cancer, your doctor will decide what additional tests may be helpful to find out if the disease has spread outside the breast. Called breast cancer staging, this process provides information about the extent of the disease. Doctors use Roman numerals to denote breast cancer stages. Breast cancer staging helps you and your doctor plan your treatment.
Information that helps determine your breast cancer stage
Your doctor determines your breast cancer stage by considering:
- The size of your tumor
- Whether cancer cells have spread to lymph nodes under your arm (axillary lymph nodes)
- Whether cancer cells have spread to other parts of your body
Tests and procedures used to stage your breast cancer
To gather the necessary information, your doctor will ask questions about your medical history, do a careful physical examination and review all the tests you've had. This can also include review of the results from the biopsy of the tumor or suspicious area. If you've already had surgery to remove your cancer and look for cancer cells in your lymph nodes, your doctor will use information from your pathology report.
Some additional tests may be needed, but most women with a new diagnosis of breast cancer don't need all the diagnostic tests available. Staging tests include:
- Blood tests. Blood tests may give your doctor an idea of your overall health and clues about which other staging tests may be useful. Blood tests might include a complete blood count and a blood chemistry test, which assess your kidney and liver function. Blood tests known as tumor markers aren't used for staging breast cancer, since they haven't been proved to reliably show the presence or absence of breast cancer cells. Breast cancer tumor markers are used only in very specific circumstances. Another blood test called a circulating tumor cell assay is being developed but can't be recommended for routine use at this time.
- Chest X-ray. A chest X-ray may reveal whether breast cancer cells have spread to your lungs.
- Additional imaging tests. Additional imaging can be used to look for breast cancer cells that have spread to other areas of your body. Not everyone with breast cancer needs these tests, though, so ask your doctor what's best for you. Additional imaging tests include a bone scan, computerized tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET).
Breast cancer stages
Breast cancer stages range from 0 to IV, with many subcategories. Lower numbers indicate earlier stages of cancer, while higher numbers reflect late-stage cancers.
This stage describes noninvasive (in situ) breast cancer. Ductal carcinoma in situ (DCIS) is an example of stage 0 cancer.
This stage is an early stage of invasive breast cancer in which:
- The tumor measures no more than 2 centimeters (cm), or about 3/4 inch, in diameter
- No lymph nodes are involved — the cancer hasn't spread outside the breast
This stage describes invasive breast cancers in which one of the following is true:
- The tumor measures less than 2 cm (about 3/4 inch) in diameter but has spread to lymph nodes under the arm.
- No tumor is found in the breast, but breast cancer cells are found in lymph nodes under the arm.
- The tumor is between 2 and 5 cm (about 3/4 to 2 inches) in diameter and may or may not have spread to lymph nodes under the arm.
- The tumor is larger than 5 cm (2 inches) in diameter but hasn't spread to any lymph nodes.
Stage III breast cancers are subdivided into three categories — IIIA, IIIB and IIIC — based on a number of criteria. By definition, stage III cancers haven't spread to distant sites.
For example, a stage IIIA tumor is larger than 5 cm (2 inches) and has spread to one to three lymph nodes under the arm. Other stage IIIA tumors may be any size and have spread into multiple lymph nodes. The lymph nodes clump and attach to one another or to the surrounding tissue.
In stage IIIB breast cancer, a tumor of any size has spread to tissues near the breast — the skin and chest muscles — and may have spread to lymph nodes within the breast or under the arm. Stage IIIB also includes inflammatory breast cancer, an uncommon but aggressive type of breast cancer.
Stage IIIC cancer is a tumor of any size that has spread:
- To 10 or more lymph nodes under the arm
- To lymph nodes above or beneath the collarbone and near the neck
- To lymph nodes within the breast itself and to lymph nodes under the arm
Stage IV breast cancer has spread to distant parts of the body, such as the lungs, liver, bones or brain.