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Abstract Purpose To investigate in a feasibility study the combination of [18F]FDG whole-body (WB) positron emission tomography-magnetic resonance (PET-MR), including an integrated breast MR within a single protocol for locoregional and distant staging in breast cancer patients. Methods Consecutive patients with breast cancer diagnoses according to conventional imaging modalities (full-field digital mammography (FFDM) and ultrasound (US)) were prospectively included. All patients underwent [18F]FDG WB PET-MR, including an integrated dedicated breast MR (prone position) and WB PET-MR (supine position) protocol. Results of [18F]FDG WB PET-MR, including integrated breast MR, versus conventional imaging modalities were compared. Results From April 2021–April 2022, 28 patients were included. On conventional imaging, cT1-2 breast cancer was present in 22 (FFDM) and 23 (US) out of 28 patients. With regard to clinical nodal status, eight patients were considered cN0, eighteen cN1 (1-3 suspicious lymph nodes), and two patients were cN2 (four suspicious axillary lymph nodes/internal mammary lymph node metastasis). [18F]FDG WB PET-MR, including an integrated breast MR protocol, upstaged clinical tumor status in two patients and clinical nodal status in nine patients according to both [18F]FDG WB PET-MR and breast MR findings. In addition, distant metastases were detected in three patients (liver/bone), and another patient was diagnosed with a synchronous primary tumor (lung cancer). Conclusion [18F]FDG WB PET-MR, including an integrated breast MR within a single protocol in breast cancer patients, is feasible and provides a promising new approach in breast cancer patients with regard to locoregional and distant staging. Critical relevance statement [18F]FDG whole-body PET-MR, including an integrated breast MR protocol, is feasible and allows locoregional and distant staging within a single imaging exam in breast cancer patients. Key Points [18F]FDG PET-MR allows the combination of breast MR and whole-body staging. Therefore, a single protocol of whole-body [18F]FDG PET-MR, including an integrated breast MRI, is investigated. [18F]FDG PET-MR, including an integrated breast MR is feasible and can be considered in daily clinical practice. Graphical Abstract

Abstract Background To quantify the relationship between [18F]FDG uptake of the primary tumour measured by PET-imaging with immunohistochemical (IHC) expression of ER, PR, HER2, Ki-67, and clinical subtypes based on these markers in breast cancer patients. Methods PubMed and Embase were searched for studies that compared SUVmax between breast cancer patients negative and positive for IHC expression of ER, PR, HER2, Ki-67, and clinical subtypes based on these markers. Two reviewers independently screened the studies and extracted the data. Standardized mean differences (SMD) and 95% confidence intervals (CIs) were estimated by using DerSimonian-Laird random-effects models. P values less than or equal to 5% indicated statistically significant results. Results Fifty studies were included in the final analysis. SUVmax is significantly higher in ER-negative (31 studies, SMD 0.66, 0.56–0.77, P

Abstract Background Neoadjuvant systemic therapy (NST) is a widely accepted initial treatment modality that can lead to pathologic downstaging of the axillary disease burden in breast cancer patients. Axillary response as well as baseline 18F-fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography with computed tomography (PET/CT) differ between breast cancer subtypes. The value of baseline 18F-FDG PET/CT in predicting axillary response to NST is not yet established, possibly since breast cancer subtype was not taken into account. The purpose of this study was to investigate the value of baseline 18F-FDG PET/CT in predicting axillary response to NST with a specific emphasis on subtype. Methods PET-parameters derived from the primary tumor as well as the most FDG-avid axillary lymph node were measured on baseline 18F-FDG PET/CT. Overall imaging findings were compared with the gold standard of histopathology of the axillary surgery specimen. Analyses for ER-positive/HER2-negative were performed separately from HER2-positive and TN patients. In addition, separate analyses for clinically node-positive patients were performed. Results Sixty-six patients with 69 primary tumors were included in this study. Thirty-three axillae contained ER-positive/HER2-negative, 16 HER2-positive, and 20 TN breast cancer. No significant difference in PET-parameters between patients with axillary residual disease and axillary pathologic complete response were found for ER-positive/HER2-negative breast cancer. In the combined HER2-positive/TN subgroup, the SUVmax was significantly lower in patients without residual axillary disease in both the entire cohort and in patients with clinically node-positive disease. In this combined subgroup, a cut-off of 4.89 SUVmax measured on the most FDG-avid axillary lymph node could predict residual axillary disease with a sensitivity, specificity, PPV, and NPV of 90%, 69%, 53%, and 95%, respectively. Conclusions Predicting axillary response following NST with baseline 18F-FDG PET/CT can be performed when focusing on breast cancer subtypes. The easily computed PET-parameter SUVmax can predict axillary response in HER2-positive and TN breast cancer. This study adds to the accumulating evidence that studies investigating the value of 18F-FDG PET/CT in breast cancer should always take subtypes into account.