¹⁸F-FDG PET/CT provides powerful prognostic stratification in the primary staging of large breast cancer when compared with conventional explorations.

PURPOSE: The objective of this study was to assess the impact on management and the prognostic value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT for initial staging of newly diagnosed large breast cancer (BC) when compared with conventional staging.

METHODS: We prospectively included 142 patients with newly diagnosed BC and at least grade T2 tumour. All patients were evaluated with complete conventional imaging (CI) procedures (mammogram and/or breast ultrasound, bone scan, abdominal ultrasound and/or CT, X-rays and/or CT of the chest), followed by FDG PET/CT exploration, prior to treatment. The treatment plan based on CI staging was compared with that based on PET/CT findings. CI and PET/CT findings were confirmed by imaging and clinical follow-up and/or pathology when assessable. Progression-free survival (PFS) was analysed using the Cox proportional hazards regression model.

RESULTS: According to CI staging, 79 patients (56%) were stage II, 46 (32%) stage III and 17 (12%) stage IV (distant metastases). Of the patients, 30 (21%) were upstaged by PET/CT, including 12 (8%) from stage II or III to stage IV. On the other hand, 23 patients (16%) were downstaged by PET/CT, including 4 (3%) from stage IV to stage II or III. PET/CT had a high or medium impact on management planning for 18 patients (13%). Median follow-up was 30 months (range 9-59 months); 37 patients (26%) experienced recurrence or progression of disease during follow-up and 17 patients (12%) died. The Cox model indicated that CI staging was significantly associated with PFS (p = 0.01), but PET/CT staging provided stronger prognostic stratification (p < 0.0001). Moreover, Cox regression multivariate analysis showed that only PET/CT staging remained associated with PFS (p < 0.0001).

CONCLUSION: FDG PET/CT provides staging information that more accurately stratifies prognostic risk in newly diagnosed large BC when compared with conventional explorations alone.