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.
If cancer cells are in the sentinel node, it means the cancer has spread beyond the breast. In the past, doctors thought that more treatment might be needed to reduce the risk of the cancer coming back (recurrence), including:
- removing other underarm lymph nodes (axillary node dissection)
- radiation therapy to the underarm lymph nodes (axillary radiation)
- hormonal therapy if the cancer is hormone-receptor-positive
But research has shown that women diagnosed with early-stage breast cancer with a positive sentinel node who have no further treatment do just as well as women who have axillary node dissection. They also had a lower risk of lymphedema. Now, another study also supports the idea that no more surgery is needed if the sentinel node is positive: the research found that axillary radiation reduces recurrence risk about the same amount as axillary lymph node surgery; axillary radiation also causes less lymphedema than axillary surgery.
The study was presented at the 2013 American Society of Clinical Oncology Annual Meeting. Read the abstract of “Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: Final analysis of the EORTC AMAROS trial (10981/22023).”
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.
In this study, called the EORTC AMAROS trial, women diagnosed with early-stage breast cancer who had positive sentinel node biopsy results were randomly split into two treatment groups:
- one group had axillary node dissection (744 women)
- the other groups had axillary radiation daily 5 days a week for 5 weeks (681 women)
The two groups were similar in terms of age, cancer size and grade, cancer characteristics, and whether the women got other treatments after surgery. The researchers compared recurrence rates, disease-free survival (how long the women lived without the cancer coming back), overall survival (how long the women lived whether or not the cancer came back), and quality of life (which included whether or not the women developed lymphedema).
After about 6 years of follow-up, the researchers found that that very few women had a recurrence:
- four women in the axillary node dissection group (0.54%)
- seven women in the axillary radiation group (1.03%)
Because these numbers were so low, it’s not clear if these numbers can be widely applied. Still, the low number of recurrences is a positive result.
Overall survival and disease-free survival were similar between the two groups.
The researchers also found that women in the axillary radiation group had less lymphedema than women who had axillary dissection:
- 22% of the women who had axillary radiation developed lymphedema
- 40% of the women who had axillary dissection developed lymphedema
This difference was significant, which means that it was likely because of the difference in treatment and not just due to chance.
The results of this study are very positive and give us more evidence that no more surgery is needed if cancer is found in the sentinel node of a woman diagnosed with early-stage breast cancer.
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 recurrence.
You can learn more by visiting the Breastcancer.org Lymph Node Removal pages.
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.