Detection of distant metastases in breast cancer patients: Comparison between [18F]-fluorodeoxyglucose positron emission tomography and conventional imaging

Abstract

1054 Background: The presence of distant metastases is a key prognostic factor in breast cancer patients and plays a central role in therapeutic decisions. To detect distant metastases, chest X-ray, abdominal ultrasound and bone scintigraphy are performed as standard of care in many centers. In various tumors, [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) detects metastatic disease with high accuracy, but the diagnostic value in breast cancer still needs to be defined. The aim of this study was to compare the diagnostic performance of FDG-PET with conventional imaging. Methods: In 119 breast cancer patients who presented for restaging, whole-body FDG-PET was compared with chest X-ray, bone scintigraphy and abdominal ultrasound. Each imaging modality was independently assessed and classified as ‘negative’, ‘equivocal’ and ‘positive’ for metastasis. The imaging results were compared with histopathology and clinical follow-up including follow-up imaging procedures which together served as the reference standard. Results: For findings classified as ‘positive’, FDG-PET detected distant metastases with a sensitivity of 87% and a specificity of 83%. In contrast, the sensitivity and specificity of combined conventional imaging procedures was 43% and 98%, respectively. The positive and negative predictive values were 89% and 82% for FDG-PET and 96% and 69% for conventional imaging. Combining ‘equivocal’ and ‘positive’ results, the sensitivity and specificity of FDG-PET was 93% and 76%, respectively, compared to 61% and 86% for conventional imaging. The positive and negative predictive values were 86% and 88% for FDG-PET versus 77% and 75% for conventional imaging. Conclusions: FDG-PET is superior to conventional imaging procedures for detection of distant breast cancer metastases. However, the use of computed tomography (CT), particularly in combined PET/CT, needs to be addressed in future studies comparing anatomical vs. metabolic staging procedures in breast cancer patients. No significant financial relationships to disclose.