SLN Mapping for Breast Cancer Feasible in Community Hospitals Hospitals

WASHINGTON—Surgeons in community hospitals as well as in university-based cancer centers can successfully find sentinel lymph nodes (SLNs) in breast cancer patients for biopsy, Douglas S. Reintgen, MD, of the H. Lee Moffitt Cancer Center, University of South Florida, Tampa, said at the 54^th Annual Cancer Symposium of the Society of Surgical Oncology (SSO).

Reporting final results from the Department of Defense Multi-Center Breast Lymphatic Mapping Trial, he said that the procedure has "the potential for being standard of care" for nodal staging in breast cancer.

Axillary lymph node status is the most powerful predictor of outcome in breast cancer, he observed. The multi-institution study aimed to determine how successfully surgeons in a variety of settings could find SLNs and also how commonly skip metastases—situations in which a sentinel node is negative but other axillary nodes are positive—occurred in patients with invasive breast cancer.

The mapping technique used in the study included both blue dye and a ra-diocolloid. In addition, the trial evaluated the utility of preoperative lymphoscin-tigraphy for mapping lymph nodes.

The study included 111 surgeons at 42 institutions, 71% of which were community hospitals. The trial involved 965 women with invasive breast cancer, 64% of whom underwent lumpectomy. Most had small, infiltrating, ductile tumors. Accrual began in July 1997 and lasted through January 1999.

Participating surgeons who were unfamiliar with lymphatic mapping using blue dye and radiocolloid took a formal course in the procedure. Each of these surgeons followed the study’s protocol I for the first 30 cases; for these patients, complete axillary lymph node dissection followed SLN mapping and SLN biopsy. All nodes excised underwent routine histologic examination for metastatic disease.

Once a surgeon had completed 30 cases and entered protocol II, complete axillary lymph node dissection was performed only when metastatic disease was found in a sentinel lymph node.

Positive nodes were found in 114 protocol I patients. Five of these women had a positive node despite a negative SLN, resulting in a skip metastasis rate of 4%. Preoperative lympho-scintigraphy revealed that 13% of the patients had extra-axillary drainage.

Surgeons successfully found a sentinel lymph node 86% of the time. Surgeons at Moffitt succeeded more often, 93% of the time, because of their extensive experience doing lymphatic mapping in breast cancer. The surgeons at the other institutions had a combined average 85% success rate at finding SLNs.

Increased experience with the technique improved surgeons’ results, Dr. Reintgen observed, noting that, "as people got through their learning curve, they did better."

Because the success rates of surgeons at community hospitals did not differ significantly from those at university medical centers, the technique has the potential to "change the staging system for breast cancer, as it did for melanoma, and the standard of care for the surgical treatment of the disease," he said.