Hypothesis: Fludeoxyglucose F 18 (FDG) positron emission tomography (PET) can be used to predict axillary node metastases.
Design: Case series.
Setting: Comprehensive breast care center.
Patients: Fifty-one women with 54 biopsy-proven invasive breast cancers.
Intervention: Whole-body FDG-PET performed before axillary surgery and interpreted blindly.
Main outcome measures: Axillary FDG activity, quantified by standardized uptake value (SUV); axillary metastases, quantified histologically; and tumor characteristics.
Results: There was PET activity in 32 axillae (59%). The SUVs ranged from 0.7 to 11.0. Twenty tumors had an SUV of 2.3 or greater, and 34 had an SUV of less than 2.3. There were no significant differences between these 2 groups except in axillary metastasis size (SUV </=2.2 vs SUV >/=2.3): mean age, 53 vs 58 years (P = .90); mean modified Bloom-Richardson score, 7.7 vs 7.6 (P = .20); lymphovascular invasion present, 25% vs 36% (P = .40); mean Ki-67 level, 25% vs 32% (P = .20); mean tumor size, 2.9 vs 3.2 cm (P = .05); and axillary metastasis size, 0.9 vs 1.7 (P = .001). By adopting an SUV threshold of 2.3, FDG-PET had a sensitivity of 60%, a specificity of 100%, and a positive predictive value of 100%.
Conclusions: Patients with an SUV greater than 2.3 had axillary metastases. This finding obviates the need for sentinel lymph node biopsy or needle biopsy to diagnose axillary involvement. Surgeons can proceed to axillary node dissection to assess the number of nodes involved, eliminate axillary disease, or perhaps provide a survival benefit if preoperative FDG-PET has an SUV greater than 2.3.