The presence of breast cancer in the lymph nodes is the first indication that cancer has spread outside the breast. To determine if the breast cancer has spread, the lymph nodes are often biopsied during a mastectomy or lymphectomy. Lymph nodes are immune organs where white blood cells, used to fight infection, amass. In the body, lymph fluid circulates through the body and then returns to the lymph nodes where it is filtered for infection and foreign bodies. When there is breast cancer in the lymph nodes, the potential for metastasis through the body is greater because cancer cells not filtered out of the lymph can be circulated to the body.
Lymph fluid from the breast tissue drains into three different lymph nodes: the axilla lymph nodes, located under the arms, and the lymph nodes near the collarbone and breast bone. The axilla lymph nodes are the first nodes that receive lymph fluid from the breast and are therefore the nodes that are biopsied. Occasionally, a special biopsy is performed called a sentinel node biopsy in which dye is injected in the breast and the first axilla node that shows dye is biopsied. The idea behind this procedure is that this sentinel node will be the most likely one to contain cancer. If cancer is found, all the lymph nodes are typically removed and tested for cancer.
To determine the spread of breast cancer in the lymph nodes, the removed nodes will be surveyed carefully. The results of the survey are typically presented to the patient as a ratio. For example, a report of three to four would mean four lymph nodes were removed and cancer was found in three of them. The higher the ratio of cancer-containing lymph nodes, the more aggressive the breast cancer treatment.
Breast cancer is divided into four stages, with stage I the least noxious and stage IV the worst. The spread of breast cancer to the lymph nodes is designated as stage II cancer. Treatment for stage II breast cancer begins with, if not already performed, a mastectomy and axillary lymphectomy. If the tumor was greater than 2 inches (5 cm) or several lymph nodes were found to be contaminated, then the surgery will often be followed by radiation of the area to destroy any cancer cells not removed by the surgery.
Adjuvant systemic therapy typically follows or is administered concurrently with the radiation to destroy any cancer cells that may have spread outside the lymph nodes. This type of therapy may involve chemotherapy, or cancer-destroying drugs; hormone therapy to reduce the production of progesterone and estrogen, breast cancer promoters; or trastuzumab, a monoclonal antibody that reduces or arrests cancer cell growth. When cancer is found in several lymph nodes, the treatment may be more aggressive and several of these therapies may be employed together.
For women with stage II breast cancer who are hesitant to have a mastectomy, neoadjuvant therapy will be tried first. This is short-term, often fairly aggressive, adjuvant systemic therapy, applied for a short time to see if the tumor can be destroyed before the breast tissue is taken. If the tumor does not shrink after a predetermined trial period, a mastectomy is strongly recommended.