Abstract:

To investigate the value of fluorodeoxyglucose positron emission tomography (FDG-PET) in detecting axillary involvement, and to compare its accuracy with sentinel lymph node biopsy (SLNB) in patients with clinically early-stage breast cancer. Materials and methods: Twenty-eight female patients with histologically-confirmed T1-2 breast cancer who were scheduled to have SLNB were included in the study. FDG-PET images were obtained 1-7 days prior to surgery with an intravenous injection of 370 MBq of FDG, while plasma glucose levels were maintained below 120 mg/dL. All the images were interpreted by 2 independent nuclear medicine specialists, who were blinded to the histological diagnoses. SLNB was performed in standard fashion with peri-tumoral injection of isosulphan blue dye. In all cases, a level I-II axillary dissection was performed following SLNB. Sentinel nodes were processed after formalin fixation; no frozen sections were used. Results: Thirteen (46%) patients were found to have axillary involvement. SLNB (an average of 2.3 LNs removed per patient) demonstrated metastases in all 13 patients. The diagnostic accuracy of FDG-PET was as follows: true-positive in 4 out of 13 patients (overall sensitivity = 31%), false-negative in 1 patient with metastasis (overall specificity = 94%), positive predictive value = 80%, negative predictive value = 63%, and accuracy = 68%. Conclusion: FDG-PET appears to be significantly less accurate than SLNB at detecting axillary metastases. In patients with an axillary-positive PET scan, however, axillary lymph node dissection may be performed without prior SLNB.

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