Purpose: (a) To compare the axillary tumor burden detected by fine-needle aspiration cytology (FNAC) versus sentinel lymph node biopsy (SLNB). (b) To evaluate the relationship between axillary tumor burden and the number of suspicious lymph nodes detected by axillary ultrasonography (US). (c) To calculate the false-positive and false-negative rates for FNAC in patients fulfilling ACOSOG Z0011 criteria.
Methods: Retrospective multicenter cross-sectional study of 355 pT1 breast cancers. SLNB and axillary lymph node dissection (ALND) were gold standards. Low axillary burden (≤2 positive lymph nodes); high burden (>2 positive lymph nodes). Patients ACOSOG Z0011: false-positive (positive FNAC+low burden), false-negative (negative FNAC+high burden).
Results: High axillary burden: in entire series 38.5% FNAC+ vs. 5.7% SLNB+ (p<0.0001). In subgroup fulfilling ACOSOG Z0011 criteria: 45.5% vs 6.7%, respectively (p<0.001). 61 positive axillary US. With 1 suspicious node on axillary US: 95.6% had ≤2 involved nodes (including pN0); with 2 suspicious nodes: 60% had >2 involved nodes. In ACOSOG Z0011 patients, with 1 suspicious node, 93.7% had ≤2 involved nodes. Of the 37 FNAC in ACOSOG Z0011patients: 54.5% false-positives for high burden; 3.8% false-negatives.
Conclusions: FNAC-positive tumors have greater axillary burden, even in patients fulfilling ACOSOG Z0011 criteria. Using axillary US/FNAC to triage patients meeting Z0011 criteria may result in axillary overtreatment. The number of suspicious nodes seen in axillary US is related with the final axillary burden and should be taken into account when deciding to do FNAC in patients fulfilling ACOSOG Z0011 criteria.
Keywords: Axillary surgery; Axillary ultrasonography; Fine-needle axillary biopsy; Overtreatment; Sentinel lymph node biopsy.
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