Positron Emission Tomography-Computed Tomography in the Detection of Axillary Lymph Node Metastasis in Patients with Early Stage Breast Cancer

OBJECTIVE: The status of axillary lymph nodes (ALNs) is the most important prognostic factor in breast cancer. The purpose of this study was to evaluate the clinical usefulness of ALN involvement by means of positron emission tomography-computed tomography (PET-CT) compared with breast sonography and mammography in patients with early breast cancer. METHODS: This study involved 108 breast cancer patients with non-palpable ALNs. All patients had PET-CT, breast sonography and mammography imaging before sentinel lymph node (SLN) biopsy. After SLN biopsy, all patients underwent complete ALN dissection. ALNs were evaluated by standard hematoxylin and eosin staining techniques. The findings of PET-CT, breast sonography and mammography imaging of 108 patients were compared with pathologic findings after surgery. Sensitivity, specificity and accuracy of individual diagnostic modalities were compared. Diagnostic accuracy was evaluated applying receiver operating characteristic (ROC) curve areas. RESULTS: The sensitivity, specificity and accuracy of PET-CT imaging were 48.5%, 84% and 73.2%, respectively. The sensitivity, specificity and accuracy of breast sonography were 51.5%, 89.3% and 77.8%, respectively. The sensitivity, specificity and accuracy of mammography were 33.3%, 96% and 76.9%, respectively. For involvement of ALNs, PET-CT imaging, breast sonography and mammography had areas under the ROC curve of 0.662, 0.704 and 0.647, respectively. CONCLUSIONS: Compared with the combination of breast sonography and mammography, PET-CT was less sensitive and had less accuracy in detecting ALN metastasis. Consequently, PET-CT is not a reliable non-invasive modality for assessing ALN involvement that can replace ALN dissection or SLN biopsy before decisions are made on appropriate systemic interventions.