SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately, 233,000 new cases of invasive breast cancer will be diagnosed in 2014 and 40,000 women will die of the disease. Surgical resection of the axillary lymph nodes in addition to potentially removing cancer that may have spread, also facilitates staging of breast cancer. 
The sentinel node is the first lymph node(s) to which cancer cells are most likely to metastasize from a primary tumor. With the introduction of intraoperative lymphatic mapping in the 1990s, Sentinel Lymph Node Biopsy (SLNB) has gained general acceptance and is the preferred procedure in appropriate circumstances. Unlike Axillary Lymph Node Dissection (ALND), SLNB is associated with a lower incidence of Lymphedema, seroma at the surgery site, paresthesias and restriction of joint movement. Nine randomized clinical trials have not shown any difference in mortality among patients who underwent ALND or SLNB for either lymph node metastases or negative sentinel lymph nodes, validating Sentinel Lymph Node Biopsy (SLNB). The American Society of Clinical Oncology (ASCO) first published guidelines on the use of SLNB for patients with early stage breast cancer in 2005, based on one randomized clinical trial. Since then, additional information from 9 randomized clinical trials and13 cohort studies pertinent to SLNB and ALND has resulted in this ASCO Clinical Practice Guideline Update.
The following recommendations were made by the American Society of Clinical Oncology panel of experts:
1) Women without sentinel lymph node (SLN) metastases should not undergo Axillary Lymph Node Dissection (ALND).
2) Women with one to two metastatic SLNs planning to undergo breast conserving surgery with whole breast radiotherapy should not undergo ALND (in most cases).
3) Women with SLN metastases who will undergo mastectomy should be offered ALND.
4) Women with operable breast cancer and multicentric tumors, those with ductal carcinoma in situ (DCIS) who will undergo mastectomy, those who previously underwent breast and/or axillary surgery and those who received preoperative/neoadjuvant systemic therapy, may be offered SLNB.
5) Women who have large or locally advanced invasive breast cancer (tumor size T3/T4), inflammatory breast cancer, or DCIS (when breast-conserving surgery is planned) or are pregnant, should not undergo SLNB.
Lyman GH, Temin S, Edge SB, et al. J Clin Oncol 2014;32:1365-1383
