An amazing new trial is changing treatment options for breast cancer patients with cancer in their lymph nodes. To better understand the importance of this new treatment option, let’s start at the beginning.
Most breast cancer starts in the cells that line the milk ducts or the milk-producing glands of the breast, but the cancer cells can migrate to other parts of the body through blood and lymphatic systems. If cancer is found in the lymph nodes, it increases the stage of a breast cancer and the risk of the cancer spreading to other parts of the body.
In the past, surgeons routinely performed a procedure called an axillary node dissection — removing lymph nodes in the underarm area and checking them to see if cancer was present. Typically, 20 to 30 lymph nodes were removed. The procedure could determine how advanced the cancer was and help the medical oncologist (a doctor who treats cancer with medications such as chemotherapy) determine the correct treatment beyond surgery.
A disadvantage of this technique is that many women are left with disabling arm swelling, a condition called lymphedema. This happens when the remaining lymph vessels cannot drain enough fluid from the chest, breast and arm, and the excess fluid builds up and causes swelling. Radiation treatment to the lymph nodes in the underarm can affect the flow of lymph fluid in the same way, further increasing the risk of lymphedema.
About 15 years ago, a new technique called sentinel node biopsy was developed, allowing breast surgeons to determine whether a patient’s breast cancer had spread to the lymph nodes without performing an axillary node dissection. Cancer migrates to certain lymph nodes first (sentinels) before moving on to other nodes. These nodes can be identified prior to surgery by injecting a patient with a radioactive substance that quickly migrates to the sentinel node. The surgeon can find the sentinel node with a special device that picks up radioactivity (like a Geiger counter). Typically, between one and four sentinel lymph nodes are identified and removed. If those nodes do not contain cancer, the remaining nodes are not removed and the risk of lymphedema is significantly reduced. Overall, about 20 percent of women with breast cancer are found to have cancer in their lymph nodes. And, until recently, if the sentinel nodes contained cancer, the remaining nodes would be removed since more of those nodes could contain cancer.
However, a recent research study called the Z-11 trial has shown that women with smaller tumors who have a positive sentinel node are safe to forgo axillary node dissection if they are having radiation and chemotherapy. The study followed two groups of women with cancer in their sentinel nodes and who were undergoing lumpectomies. One group had an axillary node dissection and one group did not. Both groups went on to have radiation and chemotherapy. There was no difference in survival or recurrence in these two groups — a significant breakthrough for women who have positive lymph nodes. It is not certain, however, whether this study can be applied to patients having mastectomies because most of them will not have radiation. Women who have lumpectomies do receive radiation.
It is important that all patients with invasive breast cancer are checked by a breast surgeon to see if their lymph nodes contain cancer. Thankfully, instead of a large, painful and potentially disfiguring operation, the much less-risky sentinel lymph node biopsy procedure can help determine if lymph nodes are involved. The fewer lymph nodes that must be removed, the less chance that lymphedema will occur, which is a huge step forward in breast cancer treatment.