Introduction: Ultrasound (US) preoperative examination of the axillary lymph nodes combined with the fine needle aspiration biopsy (FNAB) is often used in order to reduce the number of sentinel lymph node (SLN) biopsy procedures in clinically node negative breast cancer patients. The pathohistological characteristics of the ultrasonically negative axillary lymph nodes in clinically negative axillary lymph nodes are not known. The aim of our study was to compare the pathohistological characteristics of ultrasonically uninvolved axillary lymph nodes (US group) versus clinically uninvolved axillary lymph nodes (non-US group) in SLN biopsy candidates.
Methods: We included 658 patients after SLN biopsy; 286 patients in the US group and 372 in the non-US group. The pathohistological characteristics of axillary lymph nodes were evaluated by univariate analysis and logistic regression.
Results: In the univariate analysis, the proportion of macrometastastic SLN, total number of metastatic lymph nodes per patient, proportion of nonsentinel lymph node (NSLN) metastases and proportion of NSLN macrometastases were found to be lower in the US group compared to the non-US group. In the logistic regression model, only US of the axilla (p=0.010; OR: 0.57) and tumor size were significant predictors for the presence of SLN macrometastases or macrometastatic NSLN (p<0.001; OR: 0.23).
Conclusion: The patients with US negative axillary lymph nodes form a distinct subgroup of early breast cancer patients having a significantly lower tumor burden in the axillary lymph nodes compared to those with only clinically negative axillary lymph nodes.