Fluorine-18 2-deoxy-2-fluoro-D-glucose PET in the preoperative staging of breast cancer: comparison with the standard staging procedures

The present study compared the diagnostic accuracy of fluorine-18 2-deoxy-2 -fluoro-D-glucose positron emission tomography (FDG-PET) with conventional staging techniques. The differentiation between malignant and benign lesion s and the detection of multifocal disease, axillary and internal lymph node involvement, and distant metastases were evaluated. One hundred and sevent een female patients were prospectively examined using FDG-PET and conventio nal staging methods such as chest X-ray, ultrasonography of the breast and liver, mammography and bone scintigraphy. All patients were examined on a m odern full-ring PET scanner. Histopathological analysis of resected specime ns was employed as the reference method. The readers of FDG-PET were blinde d to the results of the other imaging methods and to the site of the breast tumour. The sensitivity and specificity of FDG-PET in detecting malignant breast lesions were 93% and 75% respectively. FDG-PET was twofold more sens itive (sensitivity 63%, specificity 95%) in detecting multifocal lesions th an the combination of mammography and ultrasonography (sensitivity 32%, spe cificity 93%). Sensitivity and specificity of FDG-PET in detecting axillary lymph node metastases were 79% and 92% (41% and 96% for clinical evaluatio n). FDG-PET correctly indicated distant metastases in seven patients. False -positive or false-negative findings were not encountered with FDG-PET. Che st X-ray was false-negative in three of five patients with lung metastases. Bone scintigraphy was false-positive in four patients. Three patients were upstaged since FDG-PET detected distant metastases missed with the standar d staging procedure. It is concluded that, compared with the imaging method s currently employed for initial staging, FPG-PET is as accurate in interpr eting the primary tumour and more accurate in screening for lymph node meta stases and distant metastases. Due to a false-negative rate of 20% in detec ting axillary lymph node metastases, FDG-PET cannot replace histological ev aluation of axillary status.