Stages of Breast Cancer - The TNM System

Staging Affects Treatment Options

Female anatomy, computer artwork.
Stages of Breast Cancer. SHUBHANGI GANESHRAO KENE / Getty Images

If you've had a breast biopsy, lumpectomy, or mastectomy done and gotten back the results from the pathology lab, you will want to understand what the staging part of the report means to you. Staging is related to treatment options and survival rates.

One of the first questions you may ask is, "Has the cancer spread beyond the tumor, or is it all in one place?" Right now, there is not one simple test that gives you the answer to that question.

But there is a system of categorizing cancer into stages, based on three factors. The staging system most widely used is the TNM system.

  • T is used for Tumor Size. In the image (mammogram or ultrasound) of the tumor, the radiologist can make a measurement of the tumor's size. Sometimes this is hard to do, depending on the angle of the tumor in relation to the image film, or if the tumor is deep inside the breast. A tumor has indistinct, or irregular outer edges, sometimes called a spiculated shape. They aren't always round, and they can be longer than they are wide. The most accurate way to get the size of a tumor is to surgically remove all of it, and then measure it. Tumor Size is divided into four classes: T-1 is from 0 - 2 centimeters, T-2 is from 2 - 5 cm, T-3 is greater than 5cm, and T-4 is a tumor of any size that has broken through (ulcerated) the skin, or is attached to the chest wall.
  • N is used for Lymph Node status. Since cancer can travel through your body in your lymph system, it is important to have your lymph nodes that are nearest the tumor tested for cancer and micro-metastasis. There are two ways to check the lymph nodes: by touch, and by surgery. If your lymph nodes are checked by touch, your surgeon will palpate (feel) the skin just above the lymph nodes, and rate them. If the surgeon cannot feel any swollen nodes, the rating is N-0, if the surgeon can feel some swelling and thinks the nodes are negative (not cancerous) the rating is N-1a, and if the nodes are swollen and appear positive (cancerous) the rating is N-1b. If the lymph nodes feel like they are quite swollen and bunched together (rather lumpy), they are rated N-2, or if they are near the collarbone, they are rated N-3. The second way to evaluate lymph nodes is with a sentinel node biopsy.
  • M is used for Metastasis. Metastasis affects the stage of cancer. If a sample of the nodes have been surgically removed and tested, and are clear of cancer, they are rated M-0, but if they have cancer cells or micrometastasis in them, they are rated M-1. This tells you that the tumor has shed cells beyond its original location, and that cancer may be in other parts of the body.

All of the TNM information will be combined twice, once by the surgeon, and again by the pathologist in the lab. Each expert will give an opinion about the cancer, in terms of its TNM stage. Neither of these opinions will be the exact answer to "what stage is this cancer?" You may need to know more about it, such as

  • and if it has spread (metastasized)
  • where it has traveled to in your body

All of these things affect your diagnosis, and will be considered in looking at your treatment options.

Four Stages of Breast Cancer

There are four stages of breast cancer,and your diagnosis depends on the tumor's TNM rating. Precancerous in situ carcinomas are called Stage Zero. Here's how the stage and the TNM numbers relate.

  • Stage 1 means you have a T-1 tumor and clear lymph nodes with no evidence of metastasis, or T1N0M0.
  • Stage 2 has at least three subdivisions, which are a combination of T1, T2, or T3 tumor, positive or negative lymph nodes, and no metastasis; for example T1N0M0.
  • Stage 3 also has at least three subdivisions, which come from a mix of any size of tumor, positive lymph nodes or nodes located in the collarbone area, and no metastasis; for example T3N1M0.
  • Stage 4 is also called metastatic breast cancer, and is rated by having any size of tumor, positive lymph nodes, and obvious metastasis, for example T1N1M1.

    The staging and the TNM systems are always being revised and fine-tuned, so ask your doctor to explain these results to you. Ask questions until you have an answer that you can understand. Your doctor can use a picture or a graph to help give you a clear explanation, or perhaps provide some literature for you to read later.

    Planning an Appointment with Your Doctor

    When you plan a doctor visit, and you know that you will be discussing your diagnosis, lab results, or treatment plans, you may want to ask someone to come along with you, to take notes. If that's not possible, taking a small tape recorder along is a good idea. Sometimes when ​we get unpleasant news, it is a shock to our minds or our emotions, and we may stop taking in the rest of the conversation. Having a relative or supportive friend along can really help, both in keeping a record of questions and answers, and by giving you an emotional cushion. Be sure that your friend or relative can keep your health information private, if that is what you wish.

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