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 women and their doctors want to know exactly which women are good candidates for sentinel lymph node dissection.
A 2013 study suggested that women diagnosed with breast cancer that is clinically node-positive after being treated with chemotherapy before surgery aren’t good candidates for sentinel lymph node dissection because of a false-negative rate of about 12.6%, which is considered too high.
Clinically node-positive means that a doctor can feel or see that one or more lymph nodes near the breast area are swollen during a physical exam.
Doctors call chemotherapy given before surgery 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 any cancer cells in the lymph nodes, which makes the cancer node-negative.
A false-negative result means that the results suggest that cancer isn’t present when it really is.
Now a new study suggests that using ultrasound to see if the axillary lymph nodes have cancer in them can help doctors decide which women diagnosed with node-positive breast cancer treated with chemotherapy before surgery are good candidates for sentinel lymph node surgery.
The research was published online on Feb. 2, 2015 by the Journal of Clinical Oncology. Read the abstract of “Axillary Ultrasound After Neoadjuvant Chemotherapy and Its Impact on Sentinel Lymph Node Surgery: Results From the American College of Surgeons Oncology Group Z1071 Trial (Alliance).”
This new study was done by the same researchers that did the 2013 study. As part of the earlier study, some of the women had an ultrasound of their axillary lymph nodes after chemotherapy but before breast cancer surgery.
In the new study, the researchers looked at the axillary ultrasound images of 611 women diagnosed with stage I to stage III breast cancer that hadn’t spread beyond the breast area with one to two positive lymph nodes who had been treated with neoadjuvant chemotherapy.
The researchers classified the axillary ultrasound images as suspicious, meaning the lymph nodes looked abnormal, or as normal, meaning the lymph nodes looked normal:
- 181 ultrasounds were classified as suspicious
- 430 ultrasounds were classified as normal
The researchers then compared the axillary ultrasound classification to the women’s surgery results:
- 130 women (71.8%) of the 181 who had suspicious axillary ultrasounds were node-positive at surgery
- 243 women (56.5%) of the 430 who had normal axillary ultrasounds were node-positive at surgery; of these women, 63% had just one positive node
Node-positive at surgery means that one or more lymph nodes were found to have cancer in them when the women had surgery to remove the breast cancer.
The researchers found that the 130 women with suspicious axillary ultrasounds who were node positive at surgery had more positive nodes and more cancer in those nodes than the 243 women who were node-positive at surgery who had normal axillary ultrasounds.
Based on their results, the researchers recommend using axillary ultrasound after neoadjuvant chemotherapy to help women and their doctors make a decision about which type of lymph node surgery to have. Women who have normal axillary ultrasounds are good candidates for sentinel lymph node surgery, while women with suspicious axillary ultrasounds would likely be better off having axillary lymph node surgery.
To make sure that women have the appropriate lymph node surgery, in 2014 the American Society for Clinical Oncology released guidelines on sentinel lymph node biopsy for people diagnosed with early-stage breast cancer. The guidelines say sentinel lymph node biopsy SHOULD be offered under these circumstances:
- breast cancer in which there is more than one tumor, all of which have formed separately from one another (doctors call these multicentric tumors); these types of breast cancers are rare
- DCIS treated with mastectomy
- women who have previously had breast cancer surgery or axillary lymph node surgery
- women who have been treated before surgery with chemotherapy or another systemic treatment
Sentinel node biopsy SHOULD NOT be offered under these circumstances:
- the cancer is 5 cm or larger or locally advanced (the cancer has spread extensively in the breast or to the nearby lymph nodes)
- the cancer is inflammatory breast cancer
- DCIS treated with lumpectomy
- the woman is pregnant
The guidelines also say:
- Women with negative sentinel node biopsies shouldn’t have axillary node surgery.
- Women with one or two positive sentinel nodes who plan to have lumpectomy plus radiation don’t need axillary node surgery.
- Women who have one or more positive sentinel nodes and plan to have mastectomy with no radiation should be offered axillary node surgery.
If you’ve been diagnosed with stage I to stage III breast cancer and are being treated with chemotherapy before surgery, you may want to talk to your doctor about this study and whether having an axillary ultrasound after chemotherapy is finished but before breast cancer surgery makes sense for you.
You can learn more about lymph nodes and why they may need to be removed in the Breastcancer.org Lymph Node Removal pages.
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