Lymphatic mapping techniques have the potential of changing the standard of surgical care of breast cancer patients. This paper reports a prospective study documenting the safety and efficacy of sentinel lymph node biopsy in 167 breast cancer patients and reviews the world literature on the procedure.
Methods: One hundred sixty-seven patients with newly diagnosed breast cancers underwent a prospective trial of intra-operative lymphatic mapping using a combination of vital blue dye and filtered technetium-labeled sulfur colloid. A sentinel lymph node (SLN) was defined as a blue node and/or "hot" node with a 10/1 ex-vivo gamma-probe ratio of SLN to non-SLN. All SLN were bi-valved, step-sectioned, and examined with routine H&E stains and immunohistochemical stains for cytokeratin. Cytokeratin-positive SLN were defined as any SLN with a defined cluster of positive staining cells which could be confirmed histologically on H&E sections. Finally, a review of the worldwide data was undertaken using a uniform analytical method to compare the rates of sensitivity, diagnostic accuracy, and false negatives of SLN mapping.
Results: In 167 patients, 337 SLN were harvested, for an average of 2.01 SLN/patient. Fifty-two (31.1%) of the patients had metastasis in the SLN. In the 115 patients with negative SLN, 1 was found to have tumor in higher axillary nodes, for a false negative rate of 0.88%. Fifty-nine (37.8%) of the patients were diagnosed by fine-needle aspiration, 89 (53.3%) by excisional biopsy, and 19 (11.4%) by core biopsy. Positive SLN were identified in 1/17 (5.9%) patients with DCIS. Metastasis was found in 33/115 (28.7%) of the patients with infiltrating ductal tumors and in 11/19 (57.9%) of the patients with infiltrating lobular tumors. Positive SLN were identified in 7/16 (43.7%) of the patients with mixed cellularity tumors. Metastasis in the SLN was detected in 7/55 (12.7%) of the 59 patients with T1a-T1b tumors and in 21/58 (36.2%) of the patients with T1c tumors. Positive SLN were found in 17/30 (56.7%) of the patients with T2 tumors and in 6/7 (85.7%) of the patients with T3 tumors. A literature review of 731 patients (including this study) demonstrates a sensitivity rate of 95% and a diagnostic accuracy rate of 98%. The overall false negative rate is 3.1%.
Conclusions: This study demonstrates that SLN biopsy is a highly sensitive and accurate method of predicting axillary nodal status. It is a reproducible technique that is easily learned. The future addition of more sensitive methods such as PCR evaluation of nodal involvement may reduce the need for widespread use of adjuvant chemotherapy with its high cost and attendant morbidity and mortality. We believe that this technique will eventually become the standard of care in the treatment of breast cancer, particularly for T1 and T2 lesions and perhaps also for high-grade DCIS tumors.