Breast Cancer Cells Found by Immunochemistry in Sentinel Nodes Not Associated with Survival

Breast Cancer Cells Found by Immunochemistry in Sentinel Nodes Not Associated with Survival

July 26, 2011 • Volume 8 / Number 15

The detection of breast cancer cells in sentinel lymph nodes by immunochemistry—antibody-based techniques to detect cancer cells—in addition to standard tissue staining does not appear to help predict survival after treatment for breast cancer. These results, from the American College of Surgeons Oncology Group (ACOSOG) Z0010 study, were published online July 26 in JAMA.

ACOSOG researchers from 126 hospitals, led by Dr. Armando Giuliano of the John Wayne Cancer Institute in Santa Monica, CA, enrolled 5,119 women with early-stage breast cancer and identifiable sentinel lymph nodes in the prospective observational study between May 1999 and May 2003.

Most of the women had stage I, estrogen receptor-positive breast cancer. Ninety-one percent received whole-breast radiation, 83 percent received chemotherapy, and 68 percent received hormone therapy.

Standard tissue staining found cancer cells in the sentinel lymph nodes of almost one-quarter of the women. Of the remaining women, 85 percent were assessed using immunohistochemistry (IHC). In about 10 percent of those women, IHC found occult (initially undetected) metastases in the sentinel lymph nodes that standard tissue staining had failed to detect. However, the researchers did not see a statistically significant difference in overall survival between women who did and did not have IHC-detected cancer cells in their lymph nodes.

Using a similar test called immunocytochemistry, the researchers found occult metastases in the bone marrow of 104 (3 percent) of the 3,413 women who had samples that could be tested. The presence of these cancer cells was associated with decreased overall survival. However, when other factors, such as age and tumor size, were included in the analysis, the association between occult bone marrow metastases and overall survival disappeared. The small number of women with positive bone marrow findings may explain this absence of statistical significance, noted the authors.

The researchers also pointed out that most patients in the Z0010 trial received adjuvant systemic therapy, which is standard practice in the United States, independent of immunohistochemical findings. “Thus,” wrote the authors, “although the effect of untreated micrometastases is unknown, it is not relevant to current practice” because occult sentinel lymph node metastases treated with adjuvant systemic therapy do not affect survival.

Because IHC of the sentinel nodes did not help predict survival, and the incidence of occult bone marrow metastases was “too low to recommend incorporating bone marrow aspiration biopsy into routine practice” for patients with early-stage breast cancer, the authors concluded that routine immunochemical examination of sentinel nodes and bone marrow is “not clinically warranted” for these women.

“Many laboratories currently do immunohistochemistry to look for sentinel lymph node metastases, and this study does not support this expensive practice,” agreed Dr. Jo Anne Zujewski, head of Breast Cancer Therapeutics in NCI’s Division of Cancer Treatment and Diagnosis.