What Staging Means: Understanding Your Breast Tumor Size

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doctor explaining mammogram results to patient
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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 TNM System for Breast Cancer Staging

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 positive (cancerous) the rating is N-1. 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

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 or negative lymph nodes, and obvious metastasis, for example, T1N1M1.

How Tumor Size Is Measured

Tumor sizes are measured by a radiologist using a mammogram or an ultrasound image taken of your breast. But not all tumors are simple, round shapes that are easy to measure. For example, the tumor could be elongated like a baked potato and the image could be at an angle in which the radiologist can't see all of the dimensions. And some tumors even have irregular edges so it's hard to estimate the total diameter of the tumor.

Getting a Good Image of the Tumor

In the early process of getting all the details about your cancer, you get an increasingly clear picture of the tumor. When it comes to measuring the size of your tumor before surgery, doctors rely on the results of imaging studies. Let's compare the standard breast imaging methods:

  • Mammogram: Traditional film mammography can be used to image breast tissue, but is less accurate on dense breast tissue. If you are pre-menopausal or have never been pregnant, your breasts may be dense enough to hide masses, making them harder to measure. But if you are post-menopausal, have fatty breast tissue, or have been pregnant, film mammography may accurately measure your tumor. Digital mammography works very well on dense breast tissue and may be used to get a good measurement of a mass.
  • Breast Ultrasound: Without using compression, ultrasound is great for distinguishing between a fluid-filled cyst and a dense mass such as a tumor. Ultrasound can be used to make a measurement of a breast tumor. But it may be slightly less accurate than a mammogram, as it has been found to underestimate tumor size.
  • Breast MRI: MRI is noninvasive and painless, and uses no radiation to create a series of images of your breast tissue. While a mammogram may find your lump, an MRI might be needed to measure it if your breast tissue is dense or if your biopsy shows that the mass is larger than expected. MRI can also be used during neoadjuvant chemotherapy to monitor the progress of treatment. While MRI can create a clear image of your tumor, it tends to over-estimate the actual size in three dimensions.

    Surgical Pathological Results

    Biopsies and imaging studies give an approximate measurement of your tumor. But you need the actual tumor size in order to make the best treatment decisions. Your surgeon will use the information from previous tests as guidance when removing your tumor. After a lumpectomy or mastectomy, your excised breast tissue will be combined with your biopsy tissue, and a pathologist will examine the actual mass. The pathological measurement of your tumor is the gold standard for tumor size. Your post-surgical pathology report will summarize your comprehensive diagnosis of breast cancer.

    Reasons for Conservative Surgery

    Now that you know that your post-surgery pathology report is the best way to find out your tumor size, you may be asking, "So why don't we just do the surgery first and skip all these other tests?" Your biopsy and imaging studies are done in order to guide you and your surgeon in making the most conservative choice for breast surgery.

    If a lumpectomy will remove your cancer, you may be able to avoid a mastectomy. But if neoadjuvant chemo may shrink your tumor before surgery, then you may need less tissue removed. In some cases, such as widely-scattered invasive breast cancer, a mastectomy might be the only surgical option. Having the most information and understanding the implications of your tests helps you make informed, intelligent treatment decisions.

    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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