The role of ultrasonography and FDG-PET in axillary lymph node staging of breast cancer

Abstract

The presence of axillary lymph node metastasis is the most important prognostic factor and an essential part of staging and prognosis of breast cancer. To elucidate the usefulness and accuracy of ultrasonography (US), fluorodeoxyglucose positron emission tomography (FDG-PET) scan, and combined analysis for axillary lymph node staging in breast cancer. A total of 250 consecutive breast cancer patients who had undergone US, FDG-PET, and sentinel lymph node biopsy (SLNB) before surgery from January 2005 to December 2006 were included in the study. If an axillary lymph node had a length to width ratio <or=1.5 or cortical thickening >or=3 mm or compression of the hilum on US, focal hot uptake (maximal standardized uptake value, SUVmax >or=2.0) in the ipsilateral axilla on FDG-PET, it was considered to be a metastatic lymph node. In combined analysis of US and FDG-PET, the interpretation was considered positive if at least two of any of the criteria were met. Each imaging finding was compared with a pathologic report regarding the presence of axillary lymph node metastasis, the number of metastatic lymph nodes, and the T stage of the breast mass. Pathologically confirmed axillary lymph node metastasis was noted in 73 cases (29.2%). The mean number of metastatic lymph nodes in pathology was 3.1 +/- 3.2, and the size of breast cancer was 2.0 +/- 1.04 cm. In the detection of lymph node metastasis, the diagnostic accuracy of US was 78.8% and that of FDG-PET was 76.4%. On combined US and FDG-PET, accuracy was improved (91.6%). The number of metastatic lymph nodes on pathology was correlated with the positivity of US and FDG-PET (P < 0.01). Combined evaluation of US and FDG-PET was a sensitive and accurate method for axillary lymph node staging in breast cancer.