Lessons Learned From 500 Cases of Lymphatic Mapping for Breast Cancer

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Abstract
To evaluate the factors affecting the identification and accuracy of the sentinel node in breast cancer in a single institutional experience. Few of the many published feasibility studies of lymphatic mapping for breast cancer have adequate numbers to assess in detail the factors affecting failed and falsely negative mapping procedures. Five hundred consecutive sentinel lymph node biopsies were performed using isosulfan blue dye and technetium-labeled sulfur colloid. A planned conventional axillary dissection was performed in 104 cases. Sentinel nodes were identified in 458 of 492 (92%) evaluable cases. The mean number of sentinel nodes removed was 2.1. The sentinel node was successfully identified by blue dye in 80% (393/492), by isotope in 85% (419/492), and by the combination of blue dye and isotope in 93% (458/492) of patients. Success in locating the sentinel node was unrelated to tumor size, type, location, or multicentricity; the presence of lymphovascular invasion; histologic or nuclear grade; or a previous surgical biopsy. The false-negative rate of 10.6% (5/47) was calculated using only those 104 cases where a conventional axillary dissection was planned before surgery. Sentinel node biopsy in patients with early breast cancer is a safe and effective alternative to routine axillary dissection for patients with negative nodes. Because of a small but definite rate of false-negative results, this procedure is most valuable in patients with a low risk of axillary nodal metastases. Both blue dye and radioisotope should be used to maximize the yield and accuracy of successful localizations.