Objective: To evaluate the factors affecting the identification and accuracy of the sentinel node in breast cancer in a single institutional experience.
Summary background data: 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.
Methods: 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.
Results: 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.
Conclusions: 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.