The roles of F-FDG-PET/CT and US-guided FNAC in assessment of axillary nodal metastases in breast cancer patients.

Background: There is a need for less invasive techniques for preoperative identification of axillary lymph node (ALN) metastases.

Method: Patients underwent ultrasonography (US) and F-fluorodeoxyglucose-positron emission tomography/computed tomography (F-FDG-PET/CT), and then US-guided fine needle aspiration cytology (FNAC) and/or sentinel lymph node (SLN) biopsy were performed based on the US findings of the ALNs. Subsequently, patients with positive FNAC as well as those with positive SLN underwent axillary lymph node dissection (ALND). Postoperatively, removed SLNs and ALNs were examined histologically.

Results: Fifty (85 %) of 59 patients with positive F-FDG uptake in the axilla had axillary metastases, but F-FDG uptake results were false-positive in 9 (15 %) cases. On the other hand, 29 patients with positive FNAC underwent ALND without the need for SLN biopsy, while the remaining 20 patients with negative FNAC as well as 249 patients with negative US findings underwent SLN biopsy. Subsequently, 68 patients with positive SLN underwent ALND.

Conclusions: Positive FDG uptake in the axilla does not always indicate axillary metastasis. US-guided FNAC is useful to avoid unnecessary ALND in patients with positive F-FDG uptake. However, SLN biopsy is needed in patients with negative US findings of the ALNs and those with negative FNAC.