Breast cancer acts differently in each person. The way a cancer grows is called its pathophysiology. Cancer has different phases of development. The grade of your cancer is the terminology doctors use to describe how the cancer cells look. Knowing how the cells look will help your doctor predict how fast the cancer may grow and spread. The stage of your cancer is the terminology doctors use to communicate the size of a tumor and where and how deeply it has spread. When the pathologist has examined the cells, he or she will issue a report that includes the cancer's grade and stage.
To grade your cancer, the pathologist gives your tumor a number from 1 to 3. Slower-growing tumors get a 1. Faster-growing tumors get a 3. The stage and grade of a cancer are unrelated to one another. However, the two categories combined describe the status of the cancer in such a way that your doctor can figure out how aggressively it must be treated. A Grade 3 cancer caught at a very early stage has a better prognosis than a Grade 1 cancer that isn't discovered until after it spreads. Ask your doctor to explain the grade of your cancer because it will be important when deciding on treatment.
How Breast Cancer Spreads
The first place cancer is found in the body is called the primary site or primary tumor. Breast cancer, like all cancers, can spread to other parts of the body. This is called metastatic cancer, or metastasis. When a cancer spreads, it is said to have metastasized.
The first place that breast cancer usually spreads to is the nearby lymph nodes under your arms. In some cases, it spreads to distant parts of the body, like your liver. It may also spread to your skin. Although the cancer has spread, it's not considered a new cancer. For instance, if breast cancer spreads to your liver, it is not considered liver cancer. It's called metastatic breast cancer.
The Stages of Breast Cancer
Doctors need to know what stage your breast cancer is in to decide what treatment to recommend. The stage is based on the size and extent of your tumor, the number of nodes involved, and whether the cancer has spread. Your oncologist will be able to know your stage based on information gained from a variety of tests, including the biopsy and perhaps a lymph node biopsy. All things considered, the stage of a cancer is still more important in determining the treatment strategy than its grade.
The TNM System With Breast Cancer
The TNM System is a standard system for describing the extent of a cancer's growth. It is the most common system used to stage breast cancer. The International Union Against Cancer and the American Joint Committee on Cancer developed it. Here's what the letters stand for in the TNM System:
- T refers to the size of the tumor in the breast.
- N tells whether or not the lymph nodes in the area of the breast have become cancerous.
- M tells whether or not the cancer has spread (metastasized) to other organs in the body, such as your bones, liver, or lungs.
Numerical values, from 0 to 4, are assigned to the T, N, and M categories. Once your oncologist has determined your T, N, and M stages, this information is put together in what is called stage grouping, set by the American Joint Committee on Cancer (AJCC). The AJCC stage grouping is used to determine your overall disease stage.
Stage Groupings for Breast Cancer
These are the AJCC stage groupings for breast cancer. Each TNM category, with its assigned numerical value, falls into one of these stages.
- Stage 0 (early stage): This means that DCIS, LCIS, or Paget's disease has been found. There is no actual tumor, and there are no signs of disease spreading to lymph nodes or tissue beyond the breast. With LCIS, you are at increased risk for breast cancer, but no cancer is actually present.
- Stage I (early stage): No cancer cells are found in the lymph nodes and the tumor is no more than 2 centimeters (less than one inch) across.
- Stage II (early stage): Cancer has spread to your underarm lymph nodes and/or the tumor in the breast is 2 to 5 centimeters (1 to 2 inches) across.
- Stage IIA: These are cancers where there is either no tumor or a tumor is less than 2 centimeters across, but cancer cells are in your lymph nodes. These are also cancers between 2 and 5 centimeters that have no lymph node involvement.
- Stage IIB: Two centimeters or larger, these cancers show signs of having spread to lymph nodes, but not to your chest wall or skin. Or the tumor is more than 5 centimeters across, but it has not spread to the lymph nodes or to the chest wall or skin.
- Stage III(advanced stage): This stage is also called locally advanced cancer. The tumor in your breast is usually large (more than 5 centimeters or 2 inches across), the cancer in your underarm lymph nodes is extensive, or it has spread to other lymph node areas or to other tissues near the breast.
- Stage IIIA: This stage includes any tumors fitting the description above.
- Stage IIIB: This stage includes those cancers that have spread to your chest wall or skin and maybe to nearby lymph nodes. You may also have visible symptoms such as an ulcer on your breast skin, swelling, or an "orange peel" appearance to your skin. Inflammatory breast cancer is a type of locally advanced breast cancer in this stage.
- Stage IIIC: This stage includes tumors of any size and cancer in many different lymph nodes.
- Stage IV: This is cancer that has spread to another organ in your body. It is called metastatic cancer. In this case, the size of the tumor and the extent of the spread to the lymph nodes are less important than the fact that cancer has spread from the breast to other organs of the body.