Identifying the 'Sentinel' Lymph Node May Obviate Need for Total Axillary Dissection

SAN ANTONIO--Identification of the "sentinel" lymphnode can eliminate the need for total axillary node dissectionin a substantial number of women with primary breast cancer, PeterD. Beitsch, MD, said at the San Antonio Breast Cancer Symposium.

In studies performed at the John Wayne Cancer Institute, SantaMonica, Calif, the sentinel node was identified in 128 of 173breast cancer patients. In 122 of the 128 cases, the pathologywas identical to that obtained with total axillary dissection.Though the technique has a definite learning curve, a false-negativerate of 1% is possible in experienced hands, Dr. Beitsch saidat the meeting's closing general session.

The sentinel node concept was developed by Dr. Donald Morton overthe past decade and has become an accepted part of treatment forearly-stage melanoma, said Dr. Beitsch, who was with the JohnWayne Cancer Institute at the time of the study and is now clinicalprofessor, University of Texas Southwestern Medical Center, Dallas.

The concept is based on the belief that lymphatic drainage isnot a random event, but that the precise node that drains an areaof skin can be identified. "This lymph node will be the firstto 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 ofisosulfan blue dye directly into a tumor or biopsy cavity. Fiveminutes later, an axillary incision is made, and the blue lymphaticchannel is identified and traced to the corresponding blue sentinelnode (see figure).

Dr. Beitsch's study comprised 173 consecutive patients undergoingsurgery for primary breast cancer. Of the total, 153 had segmentalmastectomy and complete axillary dissection, and the remainderhad modified radical mastectomy. The same surgeon performed allthe procedures.

Reflecting the learning curve, the sentinel node was identifiedin 56 of the first 96 patients (58%). The success rate rose to74% (72 of 97) in the second half, including 41 of the final 50(82%).

Metastases were identified in 42 of the 128 sentinel nodes identified.Overall, the pathology of the sentinel corresponded with thatof total axillary dissection in 95% of the cases. There were sixfalse-negatives, including four cases in which no blue nodes wereactually found in the axilla, and one node that was initiallynegative with routine staining but proved to be positive withimmunohistochemical staining.

"There was one truly negative sentinel node," Dr. Beitschsaid. "The node was blue, but another node in the axillahad a metastasis. We believe that the true false negative rateis 1%."

Location of the Sentinel

The California team began collecting information on the locationof the sentinel node in the last 89 cases. As expected, Dr. Beitschsaid, the sentinel node occurred most often in level 1 (48 of73 nodes identified). Thirteen patients had sentinel nodes inlevel 2, and no level 3 nodes were identified. Eleven patientshad two blue channels leading to two separate blue sentinel nodes.One patient had an interpectoral sentinel node.

Overall, there were 19 patients with only a single positive axillarynode, and the sentinel node technique correctly identified 18of these.

"Sentinel lymphadenectomy accurately identifies the nodemost likely to drain primary breast cancer," Dr. Beitschsaid. He noted that the technique improves surgical staging byidentifying nodes that could be missed by axillary sampling oreven a level 1 dissection.

Pathologic staging is improved because the technique allows extensiveexamination of the one or two sentinel nodes most likely to harbormetastases, in addition to the random sectioning of the remainingnodes from an axillary dissection specimen.

"We believe that in the future, surgeons can use lymphaticmapping and sentinel lymphadenectomy in clinically negative axillato identify the first draining node from a primary breast cancer,"Dr. Beitsch said. "The node can be extensively examined,and if it is pathologically negative, the patient can be sparedthe morbidity of an axillary dissection. If the node is positive,the patient can undergo a therapeutic dissection."

In response to questions from the audience, Dr. Beitsch said thathe and his colleagues are working with radiolabeled tracers toreplace the blue dye. The dye left one woman with a faint bluetinge in her breast. "Even though that happened in only onecase, she was not a happy lady," he observed. "I thinkthat lymphoscintigraphy ultimately will be the way to go."