When early-stage 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’s understandable that both women and their doctors want to know exactly which women are good candidates for sentinel node dissection.
A new study suggests 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 high false-negative rates.
The research was published online on Oct. 9, 2013 by The Journal of the American Medical Association. Read the abstract of “Sentinel Lymph Node Surgery After Neoadjuvant Chemotherapy in Patients With Node-Positive Breast Cancer.”
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 that cancer isn’t present when it really is.
Earlier studies looking at sentinel node dissection in women diagnosed with clinically node-positive breast cancer after neoadjuvant chemotherapy were small and the false-negative rate varied from 7% to 25%. So researchers decided to do a larger study to see if sentinel lymph node dissection was appropriate for this group of women.
This study, called the ACOSOG Z1071 trial, looked at 663 women diagnosed with stage I through stage III cancer that hadn’t spread beyond the breast area with one lymph node involved.
During the study, 649 of the women had neoadjuvant chemotherapy and then had both sentinel lymph node dissection and axillary lymph node dissection. Looking at the lymph node surgery results from these women, the researchers found:
- a sentinel lymph node couldn’t be identified in 46 women
- only one sentinel lymph node could be found in 78 women
- two or more sentinel lymph nodes could be found in 525 women
Of the 525 women with two or more sentinel lymph nodes, sentinel lymph node dissection found no cancer in 215 women. But axillary lymph node dissection found cancer in the lymph nodes of 39 of these 215 women. This means that the false-negative rate for this group of women was 12.6%.
This false-negative rate is higher than expected and means that sentinel lymph node dissection is not a good option for women diagnosed with breast cancer that is clinically node-positive after neoadjuvant chemotherapy.
While the results of this study are disappointing, they give us more information on exactly which types of breast cancer for which sentinel lymph node dissection is most appropriate.
If you've been diagnosed with breast cancer, sentinel node biopsy may be done as part of your surgery. If cancer cells are found in the sentinel node, your doctor will consider all the details of your situation, including your age and the characteristics of the cancer (size, stage, etc.) before recommending treatments to reduce the risk of the cancer coming back. Axillary lymph node dissection may be recommended.
If you have chemotherapy before surgery to shrink the tumor and there are still positive lymph nodes after chemotherapy, it’s likely that your doctor will recommend axillary lymph node dissection.
You can learn more by visiting the Breastcancer.org Lymph Node Removal section.
Editor's note: To make sure that women have the appropriate lymph node surgery, 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 with chemotherapy or another systemic treatment (treatment before surgery is called neoadjuvant 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 also 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.