SAN ANTONIO--Identification of the "sentinel" lymph node can eliminate the need for total axillary node dissection in a substantial number of women with primary breast cancer, Peter D. Beitsch, MD, said at the San Antonio Breast Cancer Symposium.
In studies performed at the John Wayne Cancer Institute, Santa Monica, Calif, the sentinel node was identified in 128 of 173 breast cancer patients. In 122 of the 128 cases, the pathology was identical to that obtained with total axillary dissection. Though the technique has a definite learning curve, a false-negative rate of 1% is possible in experienced hands, Dr. Beitsch said at the meeting's closing general session.
The sentinel node concept was developed by Dr. Donald Morton over the past decade and has become an accepted part of treatment for early-stage melanoma, said Dr. Beitsch, who was with the John Wayne Cancer Institute at the time of the study and is now clinical professor, University of Texas Southwestern Medical Center, Dallas.
The concept is based on the belief that lymphatic drainage is not a random event, but that the precise node that drains an area of skin can be identified. "This lymph node will be the first to harbor metastases from a primary melanoma," he said.
In breast cancer, using a technique pioneered by Dr. Armando Giuliano, the sentinel lymph node is found by injecting 3 cc to 5 cc of isosulfan blue dye directly into a tumor or biopsy cavity. Five minutes later, an axillary incision is made, and the blue lymphatic channel is identified and traced to the corresponding blue sentinel node (see figure).
Dr. Beitsch's study comprised 173 consecutive patients undergoing surgery for primary breast cancer. Of the total, 153 had segmental mastectomy and complete axillary dissection, and the remainder had modified radical mastectomy. The same surgeon performed all the procedures.
Reflecting the learning curve, the sentinel node was identified in 56 of the first 96 patients (58%). The success rate rose to 74% (72 of 97) in the second half, including 41 of the final 50 (82%).