18F-FDG-PET/CT in breast cancer imaging: Restaging and Implications for treatment decisions in a clinical practice setting.

Background and purpose: Although the diagnostic accuracy of 18F-fluorodeoxyglucose - positron emission tomography/computed tomography (18F-FDG-PET/CT) for breast cancer (BC) has been well studied, few studies have evaluated the impact of 18F-FDG-PET/CT on BC patient care. This study aimed to investigate restaging and 18F-FDG-PET/CT-induced changes in clinical decision-making in patients with BC.

Material and methods: We retrospectively evaluated 18F-FDG-PET/CT-scans performed for BC-related indications in a prospectively collected consecutive cohort of adult patients at Skane University Hospital, Sweden. Patients with all BC stages were included and divided into three groups based on the indication for 18F-FDG-PET/CT: Group A (primary staging), Group B (response evaluation), and Group C (recurrence). The impact of 18F-FDG-PET/CT-scans on clinical management was categorized as no change, minor change (e.g. modification of treatment plans), or major change (e.g. shift from curative to palliative treatment intention).

Results: A total of 376 scans (151 patients) were included: Group A 9.3% (35 of 376 scans), Group B 77.4% (291 of 376 scans), and Group C 13.3% (50 of 376 scans). Significant stage migration, predominantly upstaging, occurred in Group A (45.7%) and Group C (28.0%). Changes in clinical management were observed in 120 scans (31.9%), of which 66 were major and 54 were minor. The largest proportion of 18F-FDG-PET/CT-induced management changes were observed in Group A (57.1%), most commonly a shift from curative to palliative treatment intention due to upstaging.

Interpretation: Our study indicates the clinical utility of 18F-FDG-PET/CT in BC restaging and changes in clinical management; the latter observed in approximately one-third of all cases.