What information is used to decide the breast cancer stage?

There are different kinds of breast cancer staging. They may use different pieces of information to find the stage. Information that can be used in breast cancer staging includes:

• The size of the cancer in the breast. Healthcare professionals use millimeters to measure cancers. A smaller breast cancer generally has a better prognosis.
• Whether cancer cells have spread to the lymph nodes. Lymph nodes are part of the body's germ-fighting immune system. When breast cancer spreads, it often goes to the nearby lymph nodes first. The lymph nodes most often affected by breast cancer are the ones in the breast tissue and in the armpit. Breast cancer that hasn't spread to the lymph nodes generally has a better prognosis.
• Whether cancer cells have spread to other parts of the body. Breast cancer cells that break away from where they started can enter the blood vessels or the lymphatic vessels. The cells can use those vessels to travel to other parts of the body. Breast cancer that spreads to other parts of the body generally has a poorer prognosis.
• The cancer's grade. The grade tells the healthcare team how quickly the cancer is growing. Grades range from 1 to 3. A grade 1 cancer is growing slowly. A grade 3 cancer is growing quickly. A slow-growing cancer generally has a better prognosis.
• Hormone receptor status. Most breast cancer cells use the hormones estrogen and progesterone to help them grow. If you have a hormone receptor positive cancer, it means that the cancer cells have hormone receptors. The receptors catch the hormones circulating in the body. Medicine to block the hormones in the body works on these cancers. Breast cancers that have hormone receptors generally have a better prognosis.
• HER2 status. Some cancers make too much of a protein called HER2. These are called HER2-positive cancers. Medicine that targets cells making the HER2 protein works on these cancers. HER2-positive breast cancers generally have a better prognosis.
• Gene expression test results. Gene expression tests look for certain genes inside the cancer cells. The results can give the healthcare team a better idea of whether the cancer is likely or not likely to come back after treatment. One gene expression test is used in breast cancer staging, but it's only used in some situations. Not everyone needs this test.