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). A 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:
- removing other underarm lymph nodes (axillary node dissection)
- radiation therapy to the underarm lymph nodes
- hormonal therapy if the cancer is hormone-receptor-positive
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.
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.