Metabolic Characterization of Inflammatory Breast Cancer With Baseline FDG-PET/CT: Relationship With Pathologic Response After Neoadjuvant Chemotherapy, Receptor Status, and Tumor Grade.

BACKGROUND: The aim of this study was to determine if, in inflammatory breast cancer (IBC), baseline metabolic activity (maximum standardized uptake value [SUVmax]) of primary tumor and involved regional lymph nodes (IRLN) are prognostic markers of response after neoadjuvant systemic therapy (NAS). PATIENTS AND METHODS: Baseline 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography/computed tomography scans were retrospectively reviewed among 61 women with IBC who received NAS, had mastectomy, and had available pathology reports. Primary tumor and IRLN SUVmax were compared between patients with a pathologic complete response (pCR) versus those with residual disease after NAS. A multivariate Cox model was fit to evaluate the effects of SUVmax on overall survival, adjusting for pCR and stratified by receptor status and disease stage. RESULTS: SUVmax in primary IBC tumors tended to increase with tumor grade (trend test P = .06) and was lower for stage III, non-triple-negative (TN) versus stage III, TN and stage IV, non-TN disease (P = .04). Neither primary tumor nor IRLN SUVmax was significantly different comparing pCR versus residual disease after NAS. Adjusting for pathology response in the overall survival model stratified by stage and receptor status, baseline SUVmax in primary IBC tumor was associated with an estimated hazard ratio of 1.10 (95% confidence interval, 0.97-1.25; P = .15) for patients with stage III, TN and stage IV, non-TN disease. This hazard ratio corresponded to a 1.74-fold risk of death with 1 standard deviation (SD = 5.9) increase in baseline SUVmax in primary IBC tumor. CONCLUSION: 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography provides prognostic information for newly diagnosed IBC. Larger studies are needed to confirm these findings and assess how such early information could affect treatment choices for IBC in the neoadjuvant setting.