Stages of Breast Cancer
The stages of breast cancer refer to a combination of several pieces of pathology information, including:
- Diameter of the (invasive) tumor
- Nodal involvement (if lymph nodes under the arm have been affected and how many are affected)
- Other organ involvement (lung, bone, liver, brain)
Staging is important because it helps us create an individualized treatment plan for each patient.
Early Breast Cancers
Stage 0 Breast Cancer – This is noninvasive breast cancer, or DCIS. Cancer cells are limited to the lining of the ducts and have not spread beyond the duct.
Stage I (IA/B) Breast Cancer – The cancer has spread from the ducts or lobules into the nearby fatty tissue of the breast. The tumor diameter is less than 2 centimeters and there is no cancer in the lymph nodes.
Stage II (IIA/B) Breast Cancer – The cancer has spread from the ducts or lobules into the nearby fatty tissue of the breast. The tumor diameter is between 2 and 5 centimeters. At this stage the cancer may have spread to the nearby lymph nodes.
Advanced Breast Cancers
Stage III (IIIA/B) Breast Cancer – The tumor may be larger than 5 centimeters and the cancer may or may not have spread to the nodes, or the tumor is smaller with several nodes involved. Stopping the spread of the cancer is a major concern. A diagnosis of inflammatory breast cancer is classified as stage III breast cancer.
Stage IV/Metastatic Breast Cancer – The cancer has spread from the breast and lymph nodes to other parts of the body; there are usually organs involved, including the lungs, liver, bones and/or brain.
Grade and Rate of Growth
Predicting the cancer cell’s speed and way of growing is an important consideration in categorizing a patient’s breast cancer.
Rate of growth – S-phase fraction and Ki67 tests will likely be performed to measure cell growth. These tests are not always accurate, so other factors will also be used to make decisions.
Patterns of cell growth – How a cancer grows is measured on a scale of one to three, one for a cancer that grows slowly or predictably and three for a cancer that is more irregular in its growth pattern.
Necrosis/dead cells – The presence of “dead cells” is one sign that the tumor has aggressive growth.
Lymphatic invasion – If the tumor cells have gotten into the fluid channels of the breast, they are categorized this way. These cancers have an increased risk of spreading beyond the breast to lymph nodes and/or to other organs within the body.
Estrogen and progesterone receptors are another key factor in breast cancer cell growth. Your pathology report will determine if your cancer is estrogen receptor (ER) positive or negative, or progesterone receptor (PR) positive or negative. Positive hormone receptive cancers are more likely to respond to anti-estrogen therapies, like Tamoxifen or an aromatase inhibitor. Hormone negative cancers may respond to other types of treatments.
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HER2/neu is a type of oncogene that when it does not function normally, it makes extra proteins and receptors. This behavior can lead to cancer and these cancers can be difficult to treat and more likely to reoccur. If an invasive breast cancer is HER2/neu positive, then the tumor is over-expressing the HER2/new protein. Biologic tarteted therapy may be recommended (herceptin).