Preoperative identification of the sentinel lymph node in breast cancer

Background: Preoperative diagnosis of sentinel lymph node (SLN) metastasis would justify a single axillary operation. We hypothesized that ultrasound-guided core needle biopsy (USGCNB) of a morphologically normal or abnormal lymph node in the anatomic position of the SLN would accomplish this goal. Methods: A total of 179 clinically N0 breast cancer patients underwent high-resolution lower axillary ultrasound (US) evaluation with core needle biopsy and microclip placement of a node when feasible. SLN biopsy was performed in 131 patients and the node X-rayed when appropriate. The node was removed surgically, and the one identified and analyzed preoperatively was compared with it clinically, radiologically and/or pathologically. Results: A node was seen on US in 145 (81%) of 179 patients, and a core needle biopsy was performed in 121 patients. A total of 3.5 +/- 1.38 (mean +/- SD) core samples were obtained per node. Of those node biopsy samples, 55 (45.5%) had metastases. Metastasis size was 14.9 +/- 10.1 mm. Metastases were found in 9 (13.6%) of 66 patients in whom the needle core was negative; in these falsely negative biopsy samples, the node metastases were 8.73 +/- 6.24 mm (P = .120). Eight (33.3%) of 24 nodes that did not undergo biopsy had metastases. Seven (20.6%) of 34 of those not seen on US had SLN metastases. In 47 (78.3%) of 60 patients, the node that underwent core needle biopsy was the SLN found by the surgeon during surgery (P < .001). Conclusions: Preoperative identification, core needle biopsy, and documentation of metastasis in the first SLN in breast cancer was achieved by focused lower ipsilateral axillary US. Knowledge of the lymph node status might change the patient's planned surgery.