The role of sentinel lymph node biopsy in breast cancer

Lymphatic mapping and sentinel lymph node (SLN) biopsy are new techniques that accurately provide crucial staging information while inflicting far less morbidity than complete axillary dissection. As these techniques continue to gain acceptance, issues such as adequacy of training, certification, and outcomes measures become increasingly important. The purpose of this paper is to report the initial lymphatic mapping experience at the H Lee Moffitt Cancer Center and Research Institute and to provide a detailed description of the technical aspects of lymphatic mapping.

From April 1994 to April 1998, 700 patients with newly diagnosed breast cancers underwent an IRB-approved prospective trial of lymphatic mapping using a combination of Lymphazurin (USSC, Norwalk, CT) blue dye and filtered technetium 99m-labeled sulfur-colloid. Failure of the procedure was defined as the inability to detect an SLN by either radiocolloid uptake within a lymph node by the gamma probe or the inability to visualize blue staining of a lymph node. Learning curves were then generated as the failure rate versus serial number of patients for each of the 5 surgeons involved in this study.

The SLN was identified in 665 of 700 patients (95.0%). A total of 1,348 SLNs were successfully removed, of which 238 (17.7%) were positive for metastatic disease in 176 of 665 patients (26.5%). In patients who underwent a complete axillary dissection after SLN biopsy, SLNs were identified in 173 of 186 patients (93.0%). Of the 173 patients, 53 patients (30.6%) had positive SLNs and 120 patients (69.4%) had negative SLNs. In the 120 patients with negative SLNs, one patient was found to have disease on complete dissection, for a false-negative rate of 0.83% (95% CI: 0.02%, 4.6%). A learning curve representing the mean of the 5 surgeons' experience indicates that on average 23 patients are required by an individual surgeon to achieve a 90% +/- 4.5% success rate and 53 patients are required to achieve a 95% +/- 2.3% success rate (p = 0.05).

These data validate lymphatic mapping and SLN biopsy as indispensable tools in the surgical treatment of breast cancer. With adequate multidisciplinary training, these techniques can be readily implemented at institutions treating breast cancer.