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On the inaugural World Evidence-Based Healthcare Day, we look back at the successful SNAC (Sentinel Node Biopsy Versus Axillary Clearance) trial to remember the impact it has had on the treatment of women with early breast cancer.
Arm swelling a major complaint
Before the SNAC trial, most women with early breast cancer received routine axillary clearance (surgical removal of most lymph nodes in their armpit) to see if the cancer had spread. After this kind of surgery, many women complained of arm swelling, discomfort and reduced mobility that persisted for years.
Responding to women’s concerns, Australian and New Zealand surgeons and the CTC trialled a new form of surgery that was pioneered by Australian surgeons in people with melanoma. The new surgery involved injecting dye around the breast tumour, tracking the movement of the dye, and then removing only the first few lymph nodes where the dye was seen (the sentinel lymph nodes).
Trial assessed small tumours
A total of 1,088 women from Australian and New Zealand were randomly assigned either to the new surgery or the conventional procedure in the SNAC trial. The trial was initially limited to women with small tumours.
“An important part of the trial was ensuring consistent training and accreditation of surgeons performing a new procedure,” says Professor Martin Stockler from the CTC who was Clinical Lead on SNAC.
For one year, three years and five years after surgery, women who had axillary clearance reported more arm swelling and symptoms than women who had a sentinel lymph node biopsy. The new surgery procedure impacted lives of patients less than the conventional procedure.
New surgery common practice
Evidence from SNAC has resulted in widespread adoption of sentinel node based management by Australian and New Zealand surgeons treating women with early stage breast cancer.
“Women undergoing this new and less invasive surgery procedure have benefited with less arm symptoms and better quality of life out to five years,” said Prof Stockler.
A follow-on trial, SNAC2, has recruited over 300 additional women to see if the same kind of surgery is suitable for women with breast cancers that are larger or multiple.
If the outcomes of SNAC2 are as positive as they were for SNAC, then sentinel lymph node based management could become the standard of care for women with larger and multiple tumours. SNAC2 is due to complete follow-up in 2022.
 Wetzig et al 2017 “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 Lymphedema”