Accuracy of axillary ultrasound in preoperative nodal staging of breast cancer - size of metastases as limiting factor

Since the performance of surgical procedures of the axilla in the treatment of early breast cancer is decreasing, the role of axillary ultrasound (AUS) as staging procedere has newly to be addressed. The aim of this study was to determine which patient or histopathological characteristics are related to false-negative AUS. In a retrospective study design data of 470 women with primary breast cancer were collected from patient charts and imaging and pathology records were reviewed. True positive and false negative axillary ultrasound groups were compared in terms of tumor size, histological subtype, grade, estrogen receptor (ER) and HER2 status, proliferation index, number and size of nodal metastases, extracapsular extension (ECE) and lymphovascular invasion (LVI). Of 470 patients, 166 (35%) were node positive, 79 of them with suspicious AUS. Factors associated with false negative AUS by univariate analysis were included in a multivariate model. By multivariate analysis, only size of nodal metastases was an independent factor for false negative AUS. In the sentinel lymph node biopsy (SLNB) subgroup, 45% of patients had nodal metastasis size less than or equal to 5 mm. In conclusion, AUS in preoperative staging of early stage breast cancer is limited by small size of metastases in a substantial number of patients. Prospective studies have to show whether small metastatic deposits leaving in patients in case of no axillary surgery have no negative effect on disease free and overall survival.