Sentinel Lymph Node Biopsy in Primary Breast Cancer: Window to Management of the Axilla

In patients with primary breast cancer, several large, randomized prospective trials have shown that sentinel node biopsy (SNB) substantially reduces the morbidity associated with axillary surgery compared with formal axillary lymph node dissection (ALND). Moreover, the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-32 trial has demonstrated that when the sentinel node reveals no evidence of metastatic disease, then no further ALND is required. Recently, the results of the American College of Surgeons Oncology Group (ACOSOG) Z0011 trial have challenged the notion that all patients with metastases to the sentinel node require ALND. The results of this trial suggest that in selected sentinel node-positive patients, ALND can be potentially avoided. Yet, some concerns about the ACOSOG Z0011 trial have been raised, and these concerns may have implications in the widespread implementation of the results of this trial. Since the advent of the SNB technology, occult metastases within the sentinel node are frequently observed, and the significance of these findings remains controversial. Finally, this review considers special situations, such as pregnancy and the neoadjuvant setting, where the use of SNB should be applied judiciously. The SNB technology has dramatically improved the quality of life for women with breast cancer, and further modifications of its role in breast cancer treatment should be based on evidence obtained from randomized, controlled trials.