Report on Experiments and Clinical Cases ― Evaluation of Sentinel Lymph Node Biopsy in Clinically Node-Negative Breast Cancer

Background: In patients with clinically node-negative breast cancer, diagnosed with palpation and several types of imaging examination, sentinel lymph nodes accurately predict the status of the other axillary nodes, which determine the nature of subsequent adjuvant treatment. In addition, compared with axillary lymph node dissection, sentinel-node biopsy results in less postoperative morbidity, including pain, numbness, swelling, and reduced mobility in the ipsilateral arm. Methods: We analyzed the validity of the sentinel node biopsy procedure using dual-agent injection of blue dye and radioactive colloid performed in our hospital from May 2006 through March 2010. A total of 258 breasts of 253 patients were studied. Simultaneous axillary lymph node dissection was performed only if rapid intraoperative diagnosis identified metastasis in sentinel lymph nodes. The identification rate, accuracy, provisional false-negative rate, which was calculated with data from all 65 patients whose sentinel lymph nodes had metastasis, and axillary recurrence rate of sentinel node biopsy were calculated. Results: The sentinel node identification rate was 99.2%, and the accuracy of sentinel lymph node status was 98.0%. The provisional false-negative rate was 7.7%. During an observation period averaging 24 months, axillary recurrence was observed in only 1 of 256 cases (0.4%), and there were no cases of parasternal recurrence. In patients who underwent sentinel-node biopsy without axillary lymph node dissection, there was no obvious morbidity. Conclusion: Our sentinel-node biopsy procedure yielded satisfactory results, which were not inferior to the results of previous clinical trials. Thus, we conclude our sentinel-node biopsy procedure is feasible. If the efficacy and safety of sentinel-node biopsy are confirmed in several large-scale randomized controlled trials in Europe and the United States, sentinel-node biopsy will become a standard surgical technique in the management of clinically node-negative breast cancer. (J Nippon Med Sch 2011; 78: 96―100)