Micrometastases in Lymph Nodes Need Treatment

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A 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:

  • removing other underarm lymph nodes (axillary node dissection)
  • radiation therapy to the underarm lymph nodes (axillary irradiation)
  • chemotherapy after surgery (adjuvant chemotherapy)
  • hormonal therapy after surgery (adjuvant hormonal therapy) if the cancer is hormone-receptor-positive

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:

  • Some women had no micrometastases in the sentinel node.
  • Some women had isolated breast cancer cells in the sentinel node.
  • Some women had one or more micrometastases in the sentinel node.

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:

  • tumor size
  • tumor grade
  • hormone-receptor status

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.

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.

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