Ultrasound-guided fine-needle aspiration of clinically negative lymph nodes versus sentinel node mapping in patients at high risk for axillary metastasis

Background: Sonographically directed fine-needle aspiration is a less invasive and less costly alternative to sentinel node (SN) mapping in breast cancer patients at high risk for metastatic disease but with clinically negative axillae. Methods: Radiographic, cytological, and histological diagnostic data on breast primary tumors from 114 consecutive SN candidates were prospectively assessed for clinicopathologic variables associated with an increased incidence of axillary metastases. Patients in whom these variables were identified underwent sonographic examination of their axillae followed by fine-needle aspiration when abnormal nodes were detected. SN mapping was performed in patients with normal axillary sonogram results or negative cytological results. Patients with positive cytological results proceeded to complete axillary dissection. Final axillary histological outcomes from patients not meeting the high-risk criteria were recorded. Additionally, a cost analysis was performed in which the costs of ultrasonography and ultrasound-guided fine-needle aspiration of the axilla were compared with those of SN mapping. Results: According to our selection criteria, a third of the patients with clinically negative axillae (37 of 114; 32%) were considered at high risk for axillary metastases. Fifty-nine percent of these patients (22 of 37) had metastatic disease on final histological analysis. Forty percent (15 of 37) of high-risk patients were spared SN mapping, with a reduction in health care costs of 20% in this patient population. Eighty-seven percent of patients not meeting high-risk criteria were SN negative. Conclusions: This study suggests that in patients at increased risk for axillary metastases, the use of sonographic evaluation of the axilla in combination with fine-needle aspiration is not only clinically justified, but also cost-effective.