Integrated FDG-PET/CT for initial staging of breast cancer

Abstract

558 Background: Integrated FDG-PET/CT improves the diagnostic accuracy of staging of some cancers. The value of FDG-PET/CT in initial staging of breast cancer for detection of distant metastases has not been defined. Methods: Retrospective analysis of 83 consecutive women at the University of Kansas Medical Center who had a FDG-PET/CT from Jan 2005 to July 2006, at the time of initial diagnosis of invasive breast cancer. Women with symptoms suspicious for metastatic disease were excluded. Radiographic reports and patient charts were reviewed. All suspicious CT scans were re-read by a single radiologist who was blinded to the PET results. All suspicious scans were confirmed either by a biopsy or follow-up scans according to the discretion of the treating physician. Results: Median age was 52. 23 (28%) cancers were stage I, 44 (53%) stage II and 16 (19%) were stage III. 15/83 (18%) women had a suspicious FDG-PET/CT. Only 2 of these 15 women were confirmed to have metastatic disease, while 13 (16 %) had a false positive (FP) scan. In 5 women where both CT and PET were suspicious, 2 were true positives (TP) whereas 3 were FP. All 3 women who had suspicious PET but a non-suspicious CT were FP. All 7 women who had a non-suspicious PET and a suspicious CT were FP. PET influenced the CT classification by the radiologist in 5 (6%) women. 71/83 (86%) women had a negative or a non-suspicious CT. 3 women had lesions classified as non-suspicious with the help of a negative PET, two had lesions classified as suspicious with the help of a positive PET and seven had suspicious lesions on CT regardless of the PET. FDG-PET/CT resulted in unnecessary follow-up scans in eleven women, and unnecessary biopsies in two. One TP had metastatic bone disease. The other TP had a solitary liver metastasis detected by FDG-PET/CT which was resected and she has no evidence of disease after two years of follow-up. Conclusions: Given the high false positive rate and overall low incidence of metastases, routine use of FDG- PET/CT in asymptomatic women diagnosed with invasive breast cancer cannot be recommended. No significant financial relationships to disclose.