Three studies suggest that routinely removing the underarm (axillary) lymph nodes during early-stage breast cancer surgery may not make sense for most women. These results were presented at the 2010 American Society of Clinical Oncology (ASCO) annual meeting.
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. So more treatment may be needed to reduce the risk of the cancer coming back (recurrence). Treatment choices to reduce the risk of recurrence if cancer is in the sentinel node include:
- 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
In the first study, 856 women diagnosed with early-stage breast cancer had:
- lumpectomy to remove the cancer
- cancer cells in the sentinel lymph node
- traditional whole-breast radiation therapy after surgery
After radiation, the women were split into two groups. One group had axillary node dissection and the other group had no more surgery.
After about 6 years, the researchers found no differences in treatment outcomes between the two groups:
- 92.5% of women who didn't have axillary node dissection were alive after 5 years (called overall survival) compared to 91.9% of women who had axillary node dissection
- 83.8% of the women who didn't have axillary node dissection were alive with no cancer recurrence after 5 years (called progression-free survival) compared to 82.2% of women who had axillary node dissection
- 2.1% of the women who didn't have axillary node dissection had a cancer recurrence within 5 years compared to 3.7% of women who had axillary node dissection
- 1.3% of women who didn't have axillary node dissection had cancer come back in the lymph nodes compared to 0.6% of women who had axillary node dissection
In the second study, almost 4,000 women had surgery to remove early-stage breast cancer. None of the women had cancer cells in their lymph nodes. The women were split into two groups. One group had axillary node dissection and the other group had no more surgery.
After about 8 years of follow-up, the researchers found that overall survival, disease-free survival, and the risk of recurrence were the same in both groups. Still, the women who had axillary node dissection were more likely to have shoulder and arm problems:
- 19% of women who had axillary node dissection had difficulty rotating their shoulder outward on the side of the surgery compared to 13% of women who didn't have axillary node dissection
- 28% of women who had axillary node dissection had arm lymphedema (the affected arm was 5% or more larger than the unaffected arm) on the same side as the surgery compared to 17% of women who didn't have axillary node dissection
- 31% of women who had axillary node dissection had arm numbness on the same side as the surgery compared to 8% of women who didn't have axillary node dissection
These results suggest that if the sentinel node is negative, axillary node dissection may not offer any more benefits and may increases the risk of arm and shoulder problems. Most doctors don't routinely recommend axillary node dissection in women diagnosed with early-stage breast cancer if the sentinel node is negative. For doctors that still routinely recommend axillary node dissection if the sentinel node is negative in women diagnosed with early-stage breast cancer, these results suggest that may not make sense.
Some women diagnosed with early-stage breast cancer have no signs of cancer spread but later are diagnosed with metastatic breast cancer (cancer that has spread to locations away from the breast, such as the bones, liver or brain). So the third study was designed to see if a more sensitive test to detect cancer cells in the lymph nodes or bone marrow might help better predict prognosis. Being able to so could help a woman and her doctor make more informed treatment choices.
All 5,539 women in the third study had:
- lumpectomy to remove early-stage breast cancer
- sentinel node biopsy and a bone marrow sample taken to look for individual or tiny clumps of cancer cells (called micrometastases)
If the traditional way of looking for cancer cells in the sentinel lymph node and bone marrow (staining the samples and looking for cancer cells with a microscope) found no cancer, the researchers used a newer and more sophisticated method, called immune system assay or immunohistochemistry test to look at the sentinel node and bone marrow samples.
The traditional staining method found cancer in the sentinel node in 24% of the women. The more sensitive immunohistochemistry test found cancer in the sentinel node that staining didn't detect in another 10% of the women. Still, this better detection of cancer in the sentinel node didn't help predict which women were likely to survive after a breast cancer diagnosis.
The immunohistochemistry test found cancer in 3% of the bone marrow samples. In these cases, the immunohistochemistry test did help predict which women were likely to survive; women with cancer in their bone marrow were less likely to survive.
These results suggest that the immunohistochemistry test may help determine prognosis if it's used on bone marrow samples, but not sentinel node samples.
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. Axillary node dissection is one possibility.
These studies suggest that axillary node dissection may not be beneficial for many women. Still, each woman's situation is unique. For some women, the advantages of axillary node dissection may outweigh the risks. If your doctor recommends axillary node dissection, you may want to ask about these studies and how the results may apply to your situation. With the most up-to-date information, you and your doctor can make the best decisions for YOU.
You can learn more by visiting the Breastcancer.org Lymph Node Removal pages.
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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.