Discrepancy between FDG-PET/CT and contrast-enhanced CT in the staging of patients with inflammatory breast cancer: implications for treatment planning.

PURPOSE: Optimizing treatment strategies for patients with inflammatory breast cancer (IBC) relies on accurate initial staging. This study compared contrast-enhanced computed tomography (ce-CT) and FDG-PET/CT for initial staging of IBC to determine the frequency of discordance between the two imaging modalities and potential impact on management. METHODS: 81 patients with IBC underwent FDG-PET/CT and ce-CT prior to starting treatment. FDG-PET/CT and ce-CT scans were independently reviewed for locoregional and distant metastases and findings recorded by anatomic site as negative, equivocal, or positive for breast cancer involvement. Each paired ce-CT and FDG-PET/CT case was classified as concordant or discordant for findings. Discordant findings were subclassified as (a) related to the presence or absence of distant metastases; (b) affecting the locoregional radiation therapy plan; or (c) due to incidental findings not related to IBC. RESULTS: There were 47 discordant findings between ce-CT and FDG-PET/CT in 41 of 81 patients (50.6%). Thirty (63.8%) were related to the presence or absence of distant metastases; most commonly disease detection on FDG-PET/CT but not ce-CT (n = 12). FDG-PET/CT suggested alterations of the locoregional radiation therapy plan designed by CT alone in 15 patients. FDG-PET/CT correctly characterized 5 of 7 findings equivocal for metastatic IBC on ce-CT. CONCLUSIONS: This study demonstrates differences between ce-CT and FDG-PET/CT for initial staging of IBC and how these differences potentially affect patient management. Preliminary data suggest that FDG-PET/CT may be the imaging modality of choice for initial staging of IBC. Prospective trials testing initial staging with FDG-PET/CT versus important clinical end-points in IBC are warranted.

Prevalence of germline variants in inflammatory breast cancer.

BACKGROUND: Inflammatory breast cancer (IBC) is an uncommon and aggressive subtype of breast cancer associated with early disease recurrence and short survival. The prevalence of germline variants in cancer predisposition genes has not been systematically evaluated in women with IBC. METHODS: Among 301 women enrolled in the clinical IBC registry at a single institution between 2010 and 2017, 168 had documented genetic testing. A second cohort of 200 IBC cases who had panel-based germline testing performed through a commercial testing laboratory from 2012 to 2017 was added to the analyses. Personal and family cancer histories and genetic testing results were evaluated when they were available for both cohorts. RESULTS: Among 501 IBC cases, 368 had documented genetic testing. Germline mutations (56 total) were identified in 53 cases (14.4%). BRCA1 or BRCA2 mutations were found in 7.3% of the subjects, 6.3% had a mutation in other breast cancer genes (PALB2, CHEK2, ATM, and BARD1), and 1.6% had mutations in genes not associated with breast cancer. The prevalence of mutations was 24% (22 of 92) among women with triple-negative IBC, 13% (13 of 99) among women with estrogen receptor- and/or progesterone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative disease, and 9.3% (10 of 108) among women with HER2-positive IBC. CONCLUSIONS: The prevalence and diversity of germline genetic mutations among patients with IBC suggest that further studies should be performed to assess the role of inherited mutations in IBC carcinogenesis in comparison with non-IBC breast cancer. Since IBC has a high metastatic potential associated with poor prognostic outcomes, proposed future studies may also inform targeted treatment options.

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.