filippo.pesapane@unimi.it

The involvement of axillary lymph nodes is critical for appropriate treatment of breast cancer, and its evaluation is currently a hot topic of controversy across breast units. We aim to evaluate the negative predictive value (NPV) and specificity of axillary ultrasound (AUS) in the exclusion of metastatic axillary lymph node in study participants with early breast cancer.

Preoperative AUS was performed in women with T1 breast cancer, enrolled in our Institute, as a part of a multicenter randomized prospective trial. NPV and specificity were calculated for different histologic groups: all histologic evidence of tumor including micrometastases and isolated tumoral cells (ITC), then only those with metastases, and next only those with metastases >3 mm.

Preoperative AUS in 685 consecutive study participants (mean age: 49±10 years) resulted in 33/685 (4.8%) of false positive and 53/343 (15.5%) of false negative, which is reduced to 28/343 (8.1%) excluding ITC and micrometastases and to 17/343 (4.9%) considering only metastases >3 mm. Overall NPV was 597/650 (92%, 95%CI, 90-94%) including all cases of positivity to histopathological examination. Excluding ITC and micrometastases, the NPV was 620/650 (95%%, 95%CI, 94-97%). Finally, including metastases that can be detected by AUS (namely, metastases >3 mm) alone, the NPV was 628/650 (97%, 95%CI, 95-98%). Specificity of AUS in our population was 628/685 (95%, 95%CI, 93-97%).

Our results show that in women with early breast cancer, the AUS may represent an effective, non-invasive diagnostic tool for axillary staging. Considering the high NPV and specificity, AUS allows to select those women who could benefit from observation alone as a treatment approach.

Currently, the oncological community moves away from sentinel lymph nodes biopsy and our results confirmed the role of AUS as a non-invasive, low-cost, easily available and accurate modality for preoperative staging of the axilla, in women with early breast cancer.