Understanding Breast Cancer Staging

Wednesday, February 06, 2008

ROCHESTER, Minn. — After breast cancer has been diagnosed, additional tests may help determine if the disease has spread outside the breast. These and other tests contribute to a process called staging. Breast cancer staging helps patients and their doctors develop a treatment strategy and understand the most likely outcome or prognosis.

Although breast cancer staging is a complex classification system that can change as physicians learn more about the disease, it is helpful for patients to understand what factors physicians consider when identifying a diagnosis. A new feature on MayoClinic.com explains the stages of breast cancer and describes one of the most common current staging methods.

The TNM staging system includes three key components:

• Tumor (T). How large is the tumor, and has it spread to the skin or chest wall muscle? Tumor size is one of the most important predictors of how a cancer will behave.
• Node (N). Have cancer cells spread to nearby lymph nodes? Doctors note how many lymph nodes under the arm (axillary lymph nodes) test positive for cancer, because lymph node status strongly relates to prognosis. Breast cancers may be described as "node positive" or "node negative."
• Metastasis (M). Has the cancer spread to other, distant areas of the body?

The numbers assigned in these categories indicate the degree of tumor growth or spread. For example, N0 means no axillary lymph nodes are affected, while N1 means one to three nodes are positive and N2 means four to nine positive nodes.

An interactive slide show on MayoClinic.com shows how the stage of breast cancer, on a scale from stage 0 to stage IV, reflects the cancer's extent.

In addition, MayoClinic.com has recently posted a podcast about inflammatory breast cancer, a particularly rare and aggressive form of cancer.

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About Mayo Clinic

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. Doctors from every medical specialty work together to care for patients, joined by common systems and a philosophy of "the needs of the patient come first." More than 3,700 physicians, scientists and researchers, and 50,100 allied health staff work at Mayo Clinic, which has campuses in Rochester, Minn; Jacksonville, Fla; and Scottsdale/Phoenix, Ariz.; and community-based providers in more than 70 locations in southern Minnesota., western Wisconsin and northeast Iowa. These locations treat more than half a million people each year. To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. For information about research and education, visit www.mayo.edu. MayoClinic.com (www.mayoclinic.com) is available as a resource for your health stories.