Preoperative assessment of axillary lymph node status in breast cancer patients by ultrasonography combined with mammography: A STROBE compliant article

Preoperative assessment of nodal stage is of importance in breast cancer treatment decision-making. This study was done to determine the power of combined mammography and ultrasonography in differentiating N0–N1 from N2–N3 breast cancer. We retrospectively reviewed clinical data of 3944 female patients with invasive breast cancer by preoperative mammography and ultrasonography between January 2006 and December 2013 at our hospital. Pathological diagnosis was available for each patient. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of mammography alone, ultrasonography alone, and combination of them for assessment of axillary lymph node (ALN) status were calculated, using definitive histological results as the baseline. The sensitivity, specificity, PPV, NPV, and accuracy was 90.4%, 68.2%, 36.5%, 97.2%, and 71.9% for ultrasonography; was 66.9%, 80.8%, 41.3%, 92.3%, and 78.4% for mammography; and was 94.9%, 62.4%, 33.8%, and 98.4% for combined mammography and ultrasonography. For combination, accuracy and the area under the receiver operating characteristic curve was 67.9% and 0.85, respectively. In conclusion, combining ultrasonography and mammography improves the sensitivity in differentiating N0–N1 breast cancer from N2–N3 breast cancer, but leading to a reduced specificity. Addition of mammography to ultrasonography seems not to provide significant benefits in predicting ALN status in breast cancer patients.