Ten-year results from the Z0011 trial strongly suggest that routinely removing the axillary lymph nodes during lumpectomy to remove early-stage breast cancer doesn’t make sense for many women.
The study was published in the Sept. 12, 2017 issue of the journal JAMA. Read the abstract of “Effect of Axillary Dissection vs No Axillary Dissection on 10-Year Overall Survival Among Women With Invasive Breast Cancer and Sentinel Node Metastasis: The ACOSOG Z0011 (Alliance) Randomized Clinical Trial.”
The axillary lymph nodes are the lymph nodes under the arm. Surgically removing those lymph nodes is called axillary lymph node dissection.
When early-stage breast cancer is removed, the lymph node or nodes closest to the cancer -- called the sentinel node(s) -- often is removed and sent to a pathologist for evaluation. Removing just this node(s) is called sentinel lymph node dissection.
If cancer cells are in the sentinel node, it means the cancer has spread beyond the breast. So more treatment may be needed to reduce the risk of the cancer coming back (recurrence). If cancer is in the sentinel node, there are several treatment choices to reduce recurrence risk:
- axillary lymph node dissection
- axillary radiation therapy (radiation therapy to underarm lymph nodes)
- targeted therapy
- hormonal therapy (if the cancer is hormone-receptor-positive)
Lymphedema is one risk of axillary lymph node dissection. Lymphedema is swelling of the arm, hand, chest wall, trunk, and/or back caused by lymph fluid collecting in tissue after lymph nodes are removed. Edema is the medical term for swelling, so swelling caused by lymph fluid is "lymphedema." Experts estimate that up to 90% of women will experience some level of lymphedema after breast cancer surgery. Having sentinel lymph node dissection instead of axillary lymph node dissection can lower the risk of lymphedema, but there is still some risk. Research shows that between 4% and 13% of women will experience lymphedema after sentinel lymph node dissection. Besides lymphedema, problems moving the arm and shoulder can be other axillary lymph node dissection side effects.
Because of these possible side effects, axillary lymph node dissection makes sense only for women who will clearly benefit from the surgery. This study wanted to know if women diagnosed with early-stage breast cancer with cancer in the sentinel node(s) who had axillary lymph node dissection had better outcomes than women who had only sentinel lymph node dissection.
The study included 891 women diagnosed with early-stage breast cancer between May 1991 and December 2004. None of the women’s lymph nodes felt abnormal in any way (they had no palpable adenopathy) and the cancer wasn’t considered aggressive.
All the women had:
- lumpectomy to remove the breast cancer
- sentinel lymph node dissection that found cancer in one or two sentinel nodes
- whole-breast radiation therapy after surgery
Most of the women also were treated with chemotherapy and/or hormonal therapy after surgery.
After radiation therapy, the women were split into two groups:
- one group had axillary lymph node dissection
- the other group had no more surgery
The researchers published results after 5 years of follow-up that found no difference in survival between the two groups. But because most of the breast cancers were hormone-receptor-positive, the researchers wanted 10 years of follow-up data to be sure there were no differences in survival. Hormone-receptor-positive breast cancers may come back many more years after the initial diagnosis compared to hormone-receptor-negative breast cancers.
After 10 years of follow-up, the researchers again found no differences in survival between the two groups:
- 86.3% of the women who had sentinel lymph node dissection alone were alive
- 83.6% of the women who had axillary lymph node dissection after sentinel node dissection were alive
Also, the two groups of women had similar recurrence rates during the 10 years:
- 80.2% of the women who had sentinel lymph node dissection had no recurrence in the 10 years of follow-up
- 78.2% of the women who had axillary lymph node dissection after sentinel node dissection had no recurrence in the 10 years of follow-up
The researchers planned to enroll 1,900 women in the study. Still, when an early analysis showed that women who had axillary node dissection didn't do any better than women who only had sentinel node dissection, enrollment was stopped early.
In the past, most doctors thought that axillary lymph node dissection made sense for many women diagnosed with early-stage breast cancer that had spread to nearby lymph nodes. But now many doctors think that treatments such as chemotherapy and hormonal therapy after surgery may make axillary lymph node dissection unnecessary for some women. The results of this study strongly suggest that this is true.
It's also important to know that the results of this study apply only to women with the same characteristics as the women in this study:
- lymph nodes seemed normal before surgery
- had lumpectomy, radiation, and hormonal therapy and/or chemotherapy
These study results do NOT apply to:
- women with lymph nodes that are enlarged or suspicious based on a doctor's exam or testing before surgery
- women who had mastectomy with or without chemotherapy and radiation
If you've been diagnosed with early-stage 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.
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 surgery with chemotherapy or another systemic treatment (treatment before surgery is called neoadjuvant treatment)
The guidelines say 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.
For much more information on lymph node surgery, visit the Breastcancer.org Lymph Node Removal pages.