For breast cancer patients with a sentinel lymph node that appears free of cancer based on standard testing (hematoxylin-eosin staining), detection of very small areas of cancer in the lymph node through additional, more sensitive testing (immunohistochemistry) does not affect breast cancer outcomes. Standard testing of the sentinel node, therefore, appears to be sufficient. These results were published in the Journal of the American Medical Association.
For women with early breast cancer, determining whether the cancer has spread to the axillary (under the arm) lymph nodes is an important part of cancer staging. Many women initially undergo a sentinel lymph node biopsy, in which only a small number of nodes (or even a single node) is removed. If the sentinel nodes show evidence of cancer, many women then undergo additional lymph node removal.
In some cases, cancer in the lymph nodes may be too small to detect through standard procedures, but possible to detect through additional, very sensitive testing (immunohistochemistry). It’s been uncertain, however, whether use of immunohistochemistry to detect these very small areas of cancer provides a benefit.
To explore the use of immunohistochemistry for the detection of very small areas of cancer in the sentinel node, researchers evaluated information from more than 5,100 women with early-stage breast cancer. Women were treated with breast-conserving surgery, sentinel lymph node biopsy, whole-breast radiation therapy, and (when appropriate) chemotherapy and/or hormonal therapy.
Women whose sentinel nodes were cancer-free by conventional testing underwent additional testing with immunohistochemistry. Researchers also collected bone marrow samples in order to detect small areas of cancer in the bone.
- Of the sentinel nodes that tested negative (cancer-free) by conventional testing, 10.5% tested positive by immunohistochemistry. The very small areas of cancer detected only by immunohistochemistry, however, did not affect overall survival or the risk of cancer recurrence.
- Three percent of the bone marrow samples tested positive for cancer. Small areas of cancer in the bone marrow did appear to be linked with worse breast cancer outcomes, but the small number of affected women makes it difficult to draw firm conclusions. Also, collecting bone marrow samples is not routinely done.
These results suggest that standard approaches to evaluating the sentinel lymph node appear to be sufficient. Very small areas of cancer in the lymph node that are missed by hematoxylin-eosin staining but detected by immunohistochemistry do not appear to affect breast cancer outcomes.
Small areas of cancer in the bone marrow may possibly predict worse breast cancer outcomes, but do not appear to be common enough in early breast cancer to warrant routine testing.
Reference: Giuliano AE, Hawes D, Ballman KV et al. Association of occult metastases in sentinel lymph nodes and bone marrow with survival among women with early-stage invasive breast cancer. Journal of the American Medical Association. 2011;306:385-393.
Posted November 3, 2011 (Updated from the August 1, 2011 article- Micrometastases in Sentinel Node Don’t Worsen Breast Cancer Survival)