Sentinel lymph node biopsy indications and controversies in breast cancer.

Sentinel lymph node biopsy (SLNB) has become the standard of care for early breast cancer. Its use in breast cancer has been evaluated in several randomized controlled trials and validated in multiple prospective studies. Additionally, it has been verified that SLNB has decreased morbidity when compared to axillary lymph node dissection (ALND). The technique used to perform sentinel lymph node mapping was also evaluated in multiple studies and the accuracy rate increases when radiocolloid and blue dye are used in combination. As SLNB became more accepted, contraindications were delineated and are still debated. Patients who have clinically positive lymph nodes or core biopsy-proven positive lymph nodes should not have SLNB, but should have an ALND as their staging procedure. The safety of SLNB in pregnant patients is not fully established. However, patients with multifocal or multicentric breast cancer and patients having neoadjuvant chemotherapy are considered candidates for SLNB. However, the details of which specific neoadjuvant patients should have SLNB are currently being evaluated in a randomized controlled trial. Patients with ductal carcinoma in situ (DCIS) benefit from SLNB when mastectomy is planned and when there is a high clinical suspicion of invasion. With the advent of SLNB, pathologic review of breast cancer lymph nodes has evolved. The significance of occult metastasis in SLNB patients is currently being debated. Additionally, the most controversial subject with regards to SLNB is determining which patients with positive SLNs benefit from further axillary dissection.