This study found that when small groups of breast cancer cells -- called micrometastases -- are found in the sentinel lymph node during surgery to remove early-stage breast cancer, these micrometastases need to be treated to reduce the risk of the cancer coming back (recurrence). The results were presented at the 2009 American Society of Clinical Oncology (ASCO) Annual Meeting.
During surgery to remove early-stage breast cancer, 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.
Clusters of cancer cells in the sentinel node mean that the cancer has spread beyond the breast. This suggests that more treatment may be needed to reduce the risk of recurrence:
One or more of these treatments may be used if micrometastases are found in the sentinel lymph node.
The medical records of more than 1,000 women diagnosed with early-stage breast cancer were reviewed for this study. All the women had surgery to remove the breast cancer, which included sentinel node biopsy:
Among women with one or more micrometastases in the sentinel node, the women who had only the sentinel node removed were 5 times more likely to have a breast cancer recurrence than women who had axillary lymph node dissection or axillary lymph node irradiation.
These results strongly suggest that if any breast cancer micrometastases are found in the sentinel node, more treatment -- axillary lymph node dissection or axillary lymph node radiation -- is needed to reduce the risk of breast cancer recurrence. If the sentinel lymph node has no or only isolated breast cancer cells, the need for more treatment depends on other characteristics of the breast cancer:
If you've been diagnosed with early-stage breast cancer and sentinel lymph node biopsy was done during surgery to remove the cancer, talk to your doctor about the results of the biopsy. If any cancer micrometastases were found, your doctor will likely recommend (or may have already done) axillary lymph node dissection. Or your doctor may recommend axillary lymph node radiation. If any cancer micrometastases were found in the sentinel lymph node and your doctor didn't recommend or do any additional treatment, you may want to talk to your doctor about the study reviewed here. Besides axillary lymph node treatment, breast radiation therapy, chemotherapy, and hormonal therapy also may be used to lower the risk of breast cancer coming back. Together you and your doctor can decide on a treatment plan that makes the most sense for your specific situation.
Visit the Breastcancer.org Lymph Node Removal pages to learn more about how lymph nodes are removed.
ORLANDO, June 4 (MedPage Today) -- The presence of micrometastases in sentinel lymph nodes mandates additional treatment for patients with early-stage breast cancer to reduce the risk of axillary recurrence, data from a Dutch study suggest.
Micrometastases increased the five-year risk of axillary recurrence more than four-fold compared with no evidence of disease in sentinel nodes, Vivianne Tjan-Heijnen, M.D., Ph.D., of Maastricht University Medical Center in the Netherlands, reported at the American Society of Clinical Oncology meeting.
The study also showed that about 10% of physicians do not treat micrometastases, presumably because of concern about overtreatment, she added.
"For patients with completely negative nodes, omission of axillary therapy is safe and standard policy," Dr. Tjan-Heijnen concluded. "For patients with isolated tumor cells, omission of axillary therapy may only be safe in the presence of otherwise favorable tumor characteristics."
Dr. Tjan-Heijnen said she and her colleagues recommend complete axillary treatment in patients with micrometastases to reduce the risk of axillary recurrence.
Studies conducted before the sentinel node era yielded conflicting results about the prognostic implications of small nodal metastases, said Dr. Tjan-Heijnen.
The Dutch investigators recently extended the examination of prognostic significance to sentinel node biopsies in the MIRROR study (Micrometastases and Isolated Tumor Cells: Relevant and Robust Or Rubbish?).
As reported last year, MIRROR showed that both isolated tumor cells and micrometastases significantly increased the hazard for disease-free survival. Moreover, the patients benefited from adjuvant systemic therapy. (See SABCS: Nodal Micrometastases Raise Breast Recurrence Risk)
The first analysis of MIRROR data showed that almost half of 795 patients with isolated tumor cells and 15% of 1,028 with micrometastases did not receive additional therapy targeted to the axilla. Another 8% of patients received only axillary radiotherapy, said Dr. Tjan-Heijnen.
The current analysis focused on the clinical implications of not treating microscopic residual tumor or treating only with axillary radiation.
MIRROR included 2,680 patients who had sentinel node biopsies from 1997 to 2005 and a final nodal status of pN0, pN0(i+) [isolated cells], or pN1mi (micrometastases).
All patients had favorable characteristics by 2002 Dutch guidelines, defined as tumor size d1 cm irrespective of grade or tumor size 1 to 3 cm and grades 1 to 2.
Dr. Tjan-Heijnen reported that 1,218 patients had only sentinel node procedures, 1,314 had complete axillary node dissection, and 148 received axillary radiation therapy.
Only 13% of the sentinel-node group received adjuvant systemic therapy, compared with a majority of patients in the other two categories (P<0.0001).
The entire study population had a five-year axillary recurrence rate of 1.7%.
For patients with negative sentinel nodes (pN0), the recurrence rate did not differ significantly between patients who had complete axillary dissection and those who had sentinel node evaluation only (1.6% versus 2.3%).
The presence of isolated tumor cells (pN0[i+]) increased the hazard ratio for recurrence in patients who had only a sentinel node biopsy and those who had complete axillary dissection. However, the difference was not statistically significant (2.0% versus 0.9%, HR 2.39, 95% CI 0.67 to 8.48).
Patients with micrometastases (pN1mi) did have a significantly greater risk of recurrence compared with patients who had complete axillary dissection or irradiation of the axilla (5% versus 1%, HR 4.39, 95% CI 1.46 to 13.24).
None of the patients who had axillary radiotherapy after a positive sentinel node procedure had an axillary recurrence, regardless of whether the sentinel node contained isolated tumor cells or micrometastases.
The number of patients was too small (148) for meaningful comparisons with the other groups, but the findings are "provocative, challenging the current recommendation of complete axillary node dissection," said Dr. Tjan-Heijnen.
In multivariate analysis, other factors that influenced the risk of axillary recurrence in patients with micrometastases included tumor size (HR 8.62, P=0.021), histologic grade (HR 25.05, P=0.035), and negative hormone-receptor status (HR 4.96, P=0.010).
Omission of systemic therapy or breast radiotherapy did not increase the risk of axillary recurrence, the researchers noted.
Dr. Tjan-Heijnen reported no disclosures.
Primary source: Journal of Clinical Oncology Source reference: Tjan-Heijnen V, et al "Impact of omission of completion axillary lymph node dissection or axillary radiotherapy in breast cancer patients with micrometastases or isolated tumor cells in the sentinel lymph node: Results from the MIRROR study." J Clin Oncol 2009; 27(15 suppl): Abstract CRA596.
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