When breast cancer is removed, the lymph node closest to the cancer -- called the sentinel node -- often is removed and sent to a pathologist for evaluation. Removing just this one node is called sentinel node biopsy or sentinel node dissection.
To find the sentinel node, the surgeon injects a radioactive liquid, a blue dye, or both into the area around the breast cancer. The surgeon then waits to see where the dye travels and seems to concentrate. A special instrument is used to track the radioactive liquid. The dye and the radioactive liquid build up in the node that is draining lymph from the breast cancer. Sometimes there can be more than one sentinel lymph node. In other cases, the surgeon may not be able to find a sentinel node.
Removing only the sentinel node (or possibly a small cluster of two or three nodes) is less invasive surgery than axillary lymph node dissection. Axillary lymph node dissection usually removes 10 or more lymph nodes from the armpit area.
Sentinel lymph node dissection has a lower risk of lymphedema than axillary lymph node dissection. Lymphedema is the swelling of the soft tissues caused by a build-up of lymph fluid. Depending on the type of surgery and other treatments a person has, it’s possible for lymphedema to occur in the arm, hand, breast, trunk, or abdomen. The swelling can be accompanied by pain, tightness, numbness, and sometimes infection. Lymphedema can happen days, months, or years after breast cancer treatment and can be temporary or ongoing. Because lymphedema can be misdiagnosed or overlooked in mild cases, it’s difficult to know exactly how many women are affected. Experts estimate that 20-30% of women will have some type of lymphedema after breast cancer surgery.
So it makes sense that doctors want to remove as few lymph nodes as possible while still removing all that have cancer in them.
When you are diagnosed with breast cancer, your doctor will manually examine the lymph nodes under your arm by hand to feel if any of the nodes are enlarged and likely have cancer in them. If one or more nodes are enlarged, neoadjuvant chemotherapy may be recommended.
Doctors call chemotherapy given before surgery to remove breast cancer neoadjuvant chemotherapy. Chemotherapy may be given before surgery to shrink the tumor so less tissue needs to be removed. Chemotherapy before surgery also may kill cancer cells in the lymph nodes. Research suggests that neoadjuvant chemotherapy can completely destroy cancer cells in the lymph nodes in 40% to 70% of women.
A new type of lymph node surgery, called targeted axillary dissection (TAD), developed at the University of Texas MD Anderson Cancer Center, seems to allow doctors to see which lymph nodes have become cancer-free after neoadjuvant chemotherapy. This means that fewer lymph nodes can be removed.
The research was published online on Jan. 25, 2016 by the Journal of Clinical Oncology. Read the abstract of “Improved Axillary Evaluation Following Neoadjuvant Therapy for Patients With Node-Positive Breast Cancer Using Selective Evaluation of Clipped Nodes: Implementation of Targeted Axillary Dissection.”
"As chemotherapy is utilized more often before surgery, there is a greater likelihood that the disease in the lymph nodes will be eradicated and surgeons do not need to perform extensive nodal surgery," explained Abigail Caudle, M.D., assistant professor of breast surgical oncology at MD Anderson and first author of the study. "We just haven't had a good way to determine which patients have converted to node-negative status, and thereby, we are subjecting too many women to unnecessary surgery. With our study, we hoped to find a new way to target the lymph node known to have cancer, selectively remove it, look at it, and hopefully avoid additional surgery if chemotherapy has wiped out all the cancer."
The small study included 208 women diagnosed with breast cancer that had spread to the lymph nodes. During biopsy surgery, the surgeon identified and biopsied the most abnormal looking lymph node near the breast cancer. A pathologist examined the biopsy sample. If cancer was in the lymph node, a tiny clip was placed in the node so it could be identified later. The women then had chemotherapy.
TAD is essentially sentinel lymph node surgery plus the targeted removal of the tagged nodes.
The researchers wanted to know the false-negative rate of TAD, as well as sentinel node surgery. A false-negative is when the results suggest that cancer isn’t present when it really is. A high false-negative rate would mean that the new technique was probably not better than the current standard of care, which is axillary lymph node surgery for women who have cancer-positive lymph nodes before neoadjuvant chemotherapy.
After chemotherapy was completed, the women had surgery. The false-negative rate for TAD could only be determined in women who had axillary lymph node surgery, not just sentinel node surgery.
To help the surgeon and pathologist find the clipped lymph node, tiny radioactive seeds were placed in the clipped node 1 to 5 days before surgery. During surgery, a pathologist looked at the clipped node to see if it still had cancer in it.
- 191 women had axillary node surgery
- 134 women had sentinel node surgery 118 women had both sentinel node surgery and axillary node surgery
Of all the women who had axillary node surgery, 96 women had TAD. Of these 96 women, 85 also had sentinel node surgery. It was the results from these 85 women that were used to determine the TAD false negative rate.
The researchers determined that the false-negative rate for sentinel node surgery was 10.1%. The false-negative rate of TAD was 4.2%.
The researchers noted that the clipped node wasn’t identified as a sentinel node in 23% of the women. This means that the node that was confirmed to have cancer in it before chemotherapy would have been missed by sentinel node surgery alone and wouldn’t have been examined in these women.
"This study may now allow up to 40% of women who are diagnosed with axillary metastasis and undergo neoadjuvant chemotherapy to avoid more extensive and often debilitating surgery," said Henry Kuerer, M.D., Ph.D., professor of breast surgical oncology at MD Anderson and another paper author. "Our findings epitomize precision surgery in that we are specifically targeting the known disease and limiting the morbidity for our patients."
While this study isn’t a randomized, controlled trial, the results are promising and may lead to a new standard of care in the future.
For more information, visit the Breastcancer.org Lymph Node Removal pages.