PURPOSE: Determining the estrogen receptor (ER) status is essential in metastatic breast cancer (MBC) management. Whole-body ER imaging with 16α-[¹⁸F]fluoro-17β-estradiol positron emission tomography ([¹⁸F]FES-PET) is increasingly used for this purpose. To establish the clinical validity of the [¹⁸F]FES-PET, we studied the diagnostic accuracy of qualitative and quantitative [¹⁸F]FES-PET assessment to predict ER expression by immunohistochemistry in a metastasis. METHODS: In a prospective multicenter trial, 200 patients with newly diagnosed MBC underwent extensive workup including molecular imaging. For this subanalysis, ER expression in the biopsied metastasis was related to qualitative whole-body [¹⁸F]FES-PET evaluation and quantitative [¹⁸F]FES uptake in the corresponding metastasis. A review and meta-analysis regarding [¹⁸F]FES-PET diagnostic performance were performed. RESULTS: Whole-body [¹⁸F]FES-PET assessment predicted ER expression in the biopsied metastasis with good accuracy: a sensitivity of 95% (95% CI, 89 to 97), a specificity of 80% (66 to 89), a positive predictive value (PPV) of 93% (87 to 96), and a negative predictive value (NPV) of 85% (72 to 92) in 181 of 200 evaluable patients. Quantitative [¹⁸F]FES uptake predicted ER immunohistochemistry in the corresponding metastasis with a sensitivity/specificity of 91%/69% and a PPV/NPV of 90%/71% in 156 of 200 evaluable patients. For bone metastases, PPV/NPV was 92%/81%. Meta-analysis with addition of our data has increased diagnostic performance and narrowed the 95% CIs compared with previous studies with a sensitivity/specificity of both 86% (81 to 90 and 73 to 93, respectively). CONCLUSION: In this largest prospective series so far, we established the clinical validity of [¹⁸F]FES-PET to determine tumor ER status in MBC. In view of the high diagnostic accuracy of qualitatively assessed whole-body [¹⁸F]FES-PET, this noninvasive imaging modality can be considered a valid alternative to a biopsy of a metastasis to determine ER status in newly MBC (ClinicalTrials.gov identifier: NCT01957332 ).

Background: In metastatic breast cancer (MBC), [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT) can be used for staging. We evaluated the correlation between BC histopathological characteristics and [¹⁸F]FDG uptake in corresponding metastases. Patients and Methods: Patients with non-rapidly progressive MBC of all subtypes prospectively underwent a baseline histological metastasis biopsy and [¹⁸F]FDG-PET. Biopsies were assessed for estrogen, progesterone, and human epidermal growth factor receptor 2 (ER, PR, HER2); Ki-67; and histological subtype. [¹⁸F]FDG uptake was expressed as maximum standardized uptake value (SUV_max) and results were expressed as geometric means. Results: Of 200 patients, 188 had evaluable metastasis biopsies, and 182 of these contained tumor. HER2 positivity and Ki-67 ≥ 20% were correlated with higher [¹⁸F]FDG uptake (estimated geometric mean SUV_max 10.0 and 8.8, respectively; p = 0.0064 and p = 0.014). [¹⁸F]FDG uptake was lowest in ER-positive/HER2-negative BC and highest in HER2-positive BC (geometric mean SUV_max 6.8 and 10.0, respectively; p = 0.0058). Although [¹⁸F]FDG uptake was lower in invasive lobular carcinoma (n = 31) than invasive carcinoma NST (n = 146) (estimated geometric mean SUV_max 5.8 versus 7.8; p = 0.014), the metastasis detection rate was similar. Conclusions: [¹⁸F]FDG-PET is a powerful tool to detect metastases, including invasive lobular carcinoma. Although BC histopathological characteristics are related to [¹⁸F]FDG uptake, [¹⁸F]FDG-PET and biopsy remain complementary in MBC staging (NCT01957332).

The problem: Shared decision making is an important process in which healthcare professional and patient work together to reach a decision on how to solve a health problem. This decision should include patients’ needs and what matters most to them. We investigated if consultations between general practitioners in training (i.e. residents) and their patients demonstrate shared decision making. The research methods: We asked the residents and patients to respond to questions on their experience of shared decision making right after the consultation. We recorded 98 consultations of residents with their patients. Two researchers rated to what extent residents demonstrated shared decision-making behaviours during these consultations. The results: The patients reported more shared decision making than the residents (patients: 73 versus residents: 57 on a 0–100 scale). The researchers observed low levels of SDM during the consultations (19 on a 0–100 scale). Our conclusion: Residents should be aware that shared decision making does not yet frequently occur in practice. To improve the extent to which residents share decisions with their patients in general practice, residents should learn why, when, and how to involve patients in decision making during consultations.

Molecular imaging, such as positron emission tomography (PET), is increasingly used as biomarker to predict and assess treatment response in breast cancer. The number of biomarkers is expanding with specific tracers for tumour characteristics throughout the body and this information can be used to aid the decision-making process. These measurements include metabolic activity using [¹⁸F]fluorodeoxyglucose PET ([¹⁸F]FDG-PET), oestrogen receptor (ER) expression using 16α-[¹⁸F]Fluoro-17β-oestradiol ([¹⁸F]FES)-PET and human epidermal growth factor receptor 2 (HER2) expression using PET with radiolabelled trastuzumab (HER2-PET). In early breast cancer, baseline [¹⁸F]FDG-PET is frequently used for staging, but limited subtype-specific data reduce its usefulness as biomarker for treatment response or outcome. Early metabolic change on serial [¹⁸F]FDG-PET is increasingly used in the neo-adjuvant setting as dynamic biomarker to predict pathological complete response to systemic therapy, potentially allowing de-intensification or step-up intensification of treatment. In the metastatic setting, baseline [¹⁸F]FDG-PET and [¹⁸F]FES-PET can be used as biomarker to predict treatment response, in triple-negative and ER-positive breast cancer, respectively. Metabolic progression on repeated [¹⁸F]FDG-PET appears to precede progressive disease on standard evaluation imaging; however, subtype-specific studies are limited and more prospective data are needed before implementation in clinical practice. Even though (repeated) [¹⁸F]FDG-PET, [¹⁸F]FES-PET and HER2-PEt all show promising results as biomarkers to predict therapy response and outcome, for eventual integration into clinical practice, future studies will have to clarify at what timepoint this integration has to optimally take place.