Although numerous studies have shown that the status of the sentinel node is an accurate predictor of the status of the axillary nodes in breast cancer, the efficacy and safety of sentinel-node biopsy require validation. From March 1998 to December 1999, we randomly assigned 516 patients with primary breast cancer in whom the tumor was less than or equal to 2 cm in diameter either to sentinel-node biopsy and total axillary dissection (the axillary-dissection group) or to sentinel-node biopsy followed by axillary dissection only if the sentinel node contained metastases (the sentinel-node group). The number of sentinel nodes found was the same in the two groups. A sentinel node was positive in 83 of the 257 patients in the axillary-dissection group (32.3 percent), and in 92 of the 259 patients in the sentinel-node group (35.5 percent). In the axillary-dissection group, the overall accuracy of the sentinel-node status was 96.9 percent, the sensitivity 91.2 percent, and the specificity 100 percent. There was less pain and better arm mobility in the patients who underwent sentinel-node biopsy only than in those who also underwent axillary dissection. There were 15 events associated with breast cancer in the axillary-dissection group and 10 such events in the sentinel-node group. Among the 167 patients who did not undergo axillary dissection, there were no cases of overt axillary metastasis during follow-up. Sentinel-node biopsy is a safe and accurate method of screening the axillary nodes for metastasis in women with a small breast cancer.

BACKGROUND: Axillary lymph node dissection is an established component of the surgical treatment of breast cancer, and is an important procedure in cancer staging; however, it is associated with unpleasant side effects. We have investigated a radioactive tracer-guided procedure that facilitates identification, removal, and pathologic examination of the sentinel lymph node (i.e., the lymph node first receiving lymphatic fluid from the area of the breast containing the tumor) to predict the status of the axilla and to assess the safety of foregoing axillary dissection if the sentinel lymph node shows no involvement. METHODS: We injected 5-10 MBq of ^99m Tc-labeled colloidal particles of human albumin peritumorally in 376 consecutive patients with breast cancer who were enrolled at the European Institute of Oncology during the period from March 1996 through March 1998. The sentinel lymph node in each case was visualized by lymphoscintigraphy, and its general location was marked on the overlying skin. During breast surgery, the sentinel lymph node was identified for removal by monitoring the acoustic signal from a hand-held gamma ray-detecting probe. Total axillary dissection was then carried out. The pathologic status of the sentinel lymph node was compared with that of the whole axilla. RESULTS: The sentinel lymph node was identified in 371 (98.7%) of the 376 patients and accurately predicted the state of the axilla in 359 (95.5%) of the patients, with 12 false-negative findings (6.7%; 95% confidence interval = 3.5%-11.4%) among a total of 180 patients with positive axillary lymph nodes. CONCLUSIONS: Sentinel lymph node biopsy using a gamma ray-detecting probe allows staging of the axilla with high accuracy in patients with primary breast cancer. A randomized trial is necessary to determine whether axillary dissection may be avoided in those patients with an uninvolved sentinel lymph node.