Pre-operative axillary staging: should core biopsy be preferred to fine needle aspiration cytology?

To determine the diagnostic accuracy of ultrasound guided fine needle aspiration (FNA) cytology and core needle biopsy (CNB) of axillary lymph nodes pre-operatively in newly diagnosed operable primary breast cancer.

An observational study for all patients who underwent pre-operative FNA cytology or CNB during September 2013-August 2014 was conducted at our institution (County Hospital, Stafford, UK). The accuracy of pre-operative axillary staging was compared to the post-operative histology. For this sensitivity, specificity, positive predictive value (PPV) and negative predictive values (NPV) were calculated.

A total of 81 consecutive patients were evaluated by axillary ultrasound. Patients identified with potentially abnormal axillary lymph nodes underwent definitive surgery. Seven patients had positive cytology/histology who did not undergo definitive surgery and were excluded (N = 74) from the study. CNB had a sensitivity of 100% versus 72% (p = 0.006) for FNA cytology. Both had 100% specificity and PPV. The NPV of CNB was 100% versus 72% for FNA cytology. Among 35% of patients that underwent FNA cytology required repeat procedure versus 2.6% of patients who underwent CNB. 0/38 patients that had CNB required a second operation while 7/43 patients with negative FNA cytology had positive lymph nodes identified at sentinel lymph node biopsy (SLNB) requiring surgical re-intervention with axillary node clearance.

CNB was superior to FNA cytology when interrogating the axilla. We recommend CNB to be adopted routinely in pre-operative axillary staging to reduce surgical re-intervention.