Women diagnosed with isolated cancer cells in the sentinel lymph node often are considered node-negative and likely don't receive any additional treatment after surgery such as chemotherapy, hormonal therapy, or radiation therapy (treatment after surgery is called adjuvant therapy). This fairly large Danish study suggests that this treatment approach may need to change.
In this study, women diagnosed with node-negative, early-stage breast cancer -- but who actually had isolated cancer cells in the sentinel lymph node -- were 56% less likely to survive without the breast cancer coming back in the 5 years after treatment compared to women who were truly node negative (no cancer cells at all in the sentinel lymph node). This suggests that classifying cancers as node-negative when there are isolated cancer cells in the sentinel node may result in inadequate treatment and a higher risk of breast cancer coming back (recurrence).
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 -- called micrometastases -- found in the sentinel lymph node mean that the cancer has spread beyond the breast. If there are micrometastases in the sentinel node, the cancer is considered node-positive. Other research has shown that when micrometastases are found in the sentinel lymph node, the risk of the cancer coming back is higher compared to node-negative cancer. To lower the risk of node-positive breast cancer coming back, doctors may recommend one or more of the treatments below after surgery:
In this study, women diagnosed with node-positive breast cancer who got treatment after surgery were 43% more likely to survive without breast cancer coming back 5 years after treatment compared to women diagnosed with node-positive breast cancer who didn't get treatment after surgery.
Based on the results of this study, the same treatments after surgery used for node-positive early-stage breast cancer (micrometastases in the sentinel node) also may be needed when only isolated cancer cells are found in the sentinel node -- even though isolated cancer cells in the sentinel node often is considered node-negative.
If you've been diagnosed with early-stage breast cancer and a sentinel lymph node biopsy was done, ask your doctor about the specific results of the biopsy. If any cancer micrometastases were found, your doctor will likely recommend an axillary lymph node dissection. Your doctor also may recommend axillary lymph node radiation.
If the cancer was classified as node-negative, ask your doctor if there were any isolated cancer cells in the sentinel node. If isolated cancer cells were found, talk to your doctor about the results of this study and whether your treatment plan should include adjuvant radiation, chemotherapy, or hormonal therapy. Together you and your doctor can decide on a treatment plan that makes the most sense for your specific situation.
Breast cancer patients with isolated tumor cells or small clusters of cancerous cells in their lymph nodes are less likely to survive and be disease free, but fare better after receiving additional treatment such as chemotherapy, radiation therapy, or hormone therapy, a Dutch study found.
Compared to women with node-negative breast cancer, patients with isolated tumor cells in their lymph nodes were 50% less likely to survive and be disease free five years after treatment (adjusted hazard ratio 1.50; 95% CI 1.15 to 1.94).
Patients with micrometastases were 56% less likely to survive disease free (adjusted hazard ratio 1.56; 95% CI 1.15 to 2.13), according to the study, published in the August 13 New England Journal of Medicine.
The study also found that among the node-positive patients, those who received adjuvant-therapy were 43% more likely to survive disease free (adjusted hazard ratio 0.57; 95% CI 0.45 to 0.73).
When found in the lymph nodes, micrometastases and isolated tumor cells currently result in different diagnoses and treatment plans. But that may change based on the finding that both types put patients at greater risk while adjuvant treatment lowers the risk, Vivianne C.G. Tjan-Heijnen, MD, PhD, of Maastricht University Medical Center, and colleagues concluded.
"In current staging systems for breast cancer, lymph nodes containing micrometastases are classified as node-positive, whereas nodes containing isolated tumor cells are classified as node-negative," they wrote. "In view of our results, a reevaluation of current AJCC [American Joint Committee on Cancer] classification is warranted."
The study participants included women in the Netherlands who had favorable primary-tumor characteristics and underwent sentinel-node biopsy for breast cancer before 2006 which determined they had isolated tumor cells or micrometastases in their regional lymph nodes.
A control group of patients with node-negative cancer was chosen randomly from those diagnosed and treated in 2000 and 2001.
The 2,707 patients in the study were grouped according to treatment chosen by the treating physicians. Two groups included patients with micrometastases or isolated tumor cells. Some 995 of those patients received systemic adjuvant therapy, while 856 received no adjuvant therapy. The third group was the control group that comprised 856 node-negative patients who had not received adjuvant therapy.
The researchers evaluated the patients at a median of 5.1 years after diagnosis and found that 95 had died, while 2,261 were cancer free.
Patients with no cancerous cells in their lymph nodes were more likely to be alive and disease free after five years, as were node-positive patients who received adjuvant therapy (MedPage Today) -- whether they had micrometastases or isolated tumor cells.
The improved likelihood of disease-free survival for node-positive patients who received adjuvant therapy was still significant after the researchers adjusted for various factors, including age at diagnosis, tumor size and grade, hormone receptor status, and whether patients received axillary node dissection with or without axillary irradiation.
The researchers noted that most of the patients in their study were diagnosed when use of systemic adjuvant therapy was more conservative in the Netherlands and thus had less impact on micrometastases or isolated tumor cells.
"However, since chemotherapy now usually consists of potent third-generation regimens . . . the impact of systemic therapy should be increased," they wrote.
The study was funded by the Netherlands Organization for Health Research and Development and the Dutch Breast Cancer Trialists' Group.
The authors reported no financial conflicts of interest.
Primary source: The New England Journal of Medicine Source reference: Tjan-Heijnen V, et al "Micrometastases or isolated tumor cells and the outcome of breast cancer" N Engl J Med 2009; 7: 653-63.
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