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What Are the Stages of Breast Cancer?

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If you've been diagnosed with breast cancer, it’s important to ask, “What stage is it?” The answer will help you and your doctors know more about what’s ahead and decide on your treatment.

We now have many ways to find out exactly what kind of breast cancer you have. Clues come from physical exams, biopsies, X-rays, bone scans and other images, and blood tests. A doctor called a pathologist puts tissue samples from the breast and lymph glands under the microscope to tell us even more.

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Based on these findings, doctors string together letters and numbers to assign a stage to every case of breast cancer. It’s really just a way to pinpoint the diagnosis. Think of it like this: The longer the list of letters and numbers, the more exact the diagnosis and the more precise the treatment plan.

The Breast Cancer Alphabet

Here's some help to understand what your doctors have to say about breast cancer. The most common system used to describe the stages of the disease is the American Joint Committee on Cancer’s TNM system:

  • “T” stands for tumor, or the cancer tissue mass found in the breast itself. This letter is followed by a number (0-4). The higher the number, the bigger or wider the mass.
  • “N” stands for nodes, as in lymph nodes. These small filters are found throughout the body, and they're especially dense in and around the breast. They're meant to catch cancer cells before those get carried to other areas via the lymph vessels. Here, too, a number (0-3) conveys whether the cancer has spread to lymph nodes near the breast and, if so, how many.
  • “M” stands for metastasis, or the presence of cancer in an area beyond the breast and lymph nodes. The cancer has spread if there’s a “1” after the M.

Stage Codes Explained

Once doctors have given the breast cancer a TNM score, there’s another level of staging. Yes, that means adding more letters and numbers into the mix. Doctors use these as a guide to narrow down treatment options.

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