Sentinel node biopsy versus low axillary sampling in women with clinically node negative operable breast cancer

Abstract

Background: Sentinel node biopsy (SNB) was initially conceived as excision of the first station axillary lymph node(s) (LN) identified by radioactive and/or blue dye uptake. The definition was subsequently enlarged to also include palpable lymph nodes in the vicinity of sentinel node(s) (SN). We reasoned that the excision of this combination of nodes might be best achieved by sampling the lower axilla.

Methods: Each patient underwent low axillary sampling (LAS) and identification of SN in the excised specimen followed by complete axillary lymph node dissection (ALND). LAS was defined as excision of all fibrofatty tissue overlying the second digitation of serratus anterior below the intercostobrachial nerve and was carried out following a pre-operative injection of radioactive colloid and an intra-operative injection of blue dye. Blue and/or hot nodes (B&/HN) in the dissected tissue and remaining axilla, along with any palpable nodes within the sampled tissue, were defined as SN. The primary endpoint of the study was to compare false negative rates (FNR) of SN with that of LAS in predicting axillary LN status (NCT00128362).

Findings: The study was performed between March 2004 and December 2011 in 478 women with clinically node negative axilla. On histopathological evaluation the median tumor size was 2.5 cm and axillary nodal metastases were found in 34.1% of patients. The FNR of SNB (12.7%, 95% CI 8.1-19.4) and LAS (10.5%, 95% CI 6.6-16.2) were not significantly different (p = 0.56). The FNR of B&/HN alone, without palpable nodes, (29.0%, 95% CI 22.5-36.6) was significantly inferior to those of SNB (p = 0.0007) and LAS (p = 0.0003).

Interpretation: LAS is as accurate as SNB in predicting axillary LN status in women with clinically node negative operable breast cancer. Confining SNB procedure to excision of B&/HN, significantly increases the risk of leaving behind metastatic lymph nodes in the axilla. LAS is an effective and low cost procedure that minimizes axillary surgery and can be implemented widely. Registry Name: Clinicaltrials.gov.

Registration number: NCT00128362.

Keywords: Low axillary sampling; Sentinel node biopsy.