Sentinel Node biopsy versus Axillary Clearance Part 1 (SNAC 1)

2 April 2017


This study investigated whether sentinel node biopsy resulted in less morbidity (side effects) than immediate axillary clearance and whether this lesser surgery to the armpit had equivalent cancer-related outcomes in women with early breast cancer.

Scientific Title

Sentinel node biopsy versus axillary clearance in operable breast cancer.  The RACS SNAC Trial.  A multicentre randomised trial of the Royal Australasian College of Surgeons Section of Breast Surgery in collaboration with the NHMRC Clinical Trials Centre.


The status of the axillary or armpit lymph nodes remains the most important indicator of outcome for women with breast cancer and helps predict the need for further treatment (e.g. chemotherapy or radiotherapy). Traditionally, axillary node status has been determined by removal of most of the nodes (axillary clearance or dissection).  This operation may lead to arm swelling (lymphoedema), pain, some abnormal skin sensation, or shoulder stiffness.


This study has established that for women with small unifocal (single) breast cancers the surgical removal of the “sentinel” nodes (i.e. the first lymph node/s draining from the region of the breast cancer) provides accurate information as to whether axillary nodes are involved with cancer or not. SNAC1 has shown significantly reduced side effects with removal of sentinel nodes compared with axillary dissection. This trial has also shown a small, but increased risk of local recurrence in the axilla with sentinel node based management. This is not big enough to influence decision making for women with smaller breast cancers but is of greater importance in the discussion for women with larger and bad biology cancers.


Sentinel-Lymph-Node-Based Management or Routine Axillary Clearance? Five-Year Outcomes of the RACS Sentinel Node Biopsy Versus Axillary Clearance (SNAC) 1 Trial: Assessment and Incidence of True Lymphoedema. Neil Wetzig, Peter Grantley Gill, David Espinoza, Martin R Stockler, Val J Gebski, Owen Ung, Ian Campbell, John Simes. Annals of Surgical Oncology. April, 2017; 24 (4); 1064-1070.