Axillary lymph nodes: US-guided fine-needle aspiration for initial staging of breast cancer--correlation with primary tumor size.

PURPOSE: To retrospectively assess the sensitivity and specificity of ultrasonographic (US)-guided fine-needle aspiration (FNA) of axillary lymph nodes for preoperative staging of breast cancer across a range of primary tumor sizes, by using histologic findings as a reference standard.
MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study; informed consent was waived. US-guided FNA results in 74 patients with breast cancer (75 axillae) were compared with final pathologic results. Lymph nodes were classified as benign, indeterminate, or suspicious on the basis of US characteristics at retrospective review. US-guided FNA in the most suspicious node at US, or the largest node if all appeared benign, was performed. Final pathologic results (sentinel lymph node biopsy [SNB] or axillary lymph node dissection [ALND]) were compared with US and preoperative US-guided FNA results. Results were assessed according to tumor size. Sensitivity, specificity, and positive predictive value of US and US-guided FNA were calculated.
RESULTS: Primary tumor sizes were 0.3-12 cm (mean, 3 cm). Patient age range was 31-81 years (mean age, 51 years). Sensitivity of US-guided FNA for predicting positive results at ALND or SNB was 71%-75%. Specificity was 100%. Sensitivity of US-guided FNA increased with primary tumor size.
CONCLUSION: US-guided FNA of axillary lymph nodes in patients with newly diagnosed breast cancer had a sensitivity that increased with increasing size of the primary tumor. RSNA, 2007