PET Imaging for Breast Cancer

Imaging plays an integral role in the clinical care of patients with breast cancer. This review article focuses on the use of PET imaging for breast cancer, highlighting the clinical indications and limitations of 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) PET/CT, the potential use of PET/MRI, and 16α-[¹⁸F]fluoroestradiol (FES), a newly approved radiopharmaceutical for estrogen receptor imaging.

Leveraging Antiprogestins in the Treatment of Metastatic Breast Cancer

Although incurable, the prognosis for patients with metastatic breast cancer (MBC) has considerably improved with the approvals of multiple targeted and cytotoxic therapies. For hormone receptor-positive (HR+), ie, estrogen receptor and progesterone receptor positive (ER+/PgR+) and human epidermal growth factor receptor-2 negative (ie, ERBB2 gene nonamplified or HER2-) MBC, current approved treatment options include palliative endocrine therapy (ET), cyclin-dependent kinase (CDK 4/6) inhibitors, mTOR inhibitors, and PI3 kinase inhibitors. Most treatments target ER+ disease regardless of PgR status. Although the presence of PgR is crucial for ER+ cell proliferation in both normal and malignant mammary tissue, currently, there are no approved treatments that specifically target PgR. Recent literature has demonstrated the potential of antiprogestins in the treatment of MBC both in preclinical and clinical studies. Antiprogestins, including selective PgR modulators (SPRMs) that act as PgR antagonists, are a promising class of therapeutics for overcoming endocrine resistance in patients who develop activating estrogen receptor 1 (ESR1) and phosphatidylinositol 3-kinase (PI3K) gene mutations after prior endocrine therapy. Herein, we summarize the role of PgR and antiprogestins in the treatment of MBC. Other aspects on the use of functional imaging, clinical trials incorporating novel antiprogestins, and potential treatment combinations to overcome endocrine resistance will be briefly discussed.

Occult Rosacea Diagnosed After Recurring Blepharoplasty Incision Inflammation

We report an unusual case of a 58-year-old Caucasian female who developed intermittent eyelid erythema, edema, and wound thickening in the early postoperative period after bilateral upper eyelid blepharoplasty. These flares of inflammation sometimes appeared to respond to systemic antibiotics and steroid preparations and sometimes not. Because of concerns for possible mycobacterial infection, biopsy of the upper eyelid incision was performed and histopathology confirmed rosacea. Symptoms resolved with oral azithromycin. Our patient did not have a diagnosis of rosacea preoperatively. We believe that rosacea should be kept in mind in cases with either prolonged inflammation or recurrent inflammation in previously quiet eyelid incisions.

Measuring Glucose Uptake in Primary Invasive Breast Cancer Using Simultaneous Time-of-Flight Breast PET/MRI: A Method Comparison Study with Prone PET/CT

Purpose

To compare the measurement of glucose uptake in primary invasive breast cancer using simultaneous, time-of-flight breast PET/MRI with prone time-of-flight PET/CT.

Materials and Methods

In this prospective study, women with biopsy-proven invasive breast cancer undergoing preoperative breast MRI from 2016 to 2018 were eligible. Participants who had fasted underwent prone PET/CT of the breasts approximately 60 minutes after injection of 370 MBq (10 mCi) fluorine 18 fluorodeoxyglucose (18F-FDG) followed by prone PET/MRI using standard clinical breast MRI sequences performed simultaneously with PET acquisition. Volumes of interest were drawn for tumors and contralateral normal breast fibroglandular tissue to calculate standardized uptake values (SUVs). Spearman correlation, Wilcoxon signed ranked test, Mann-Whitney test, and Bland-Altman analyses were performed.

Results

Twenty-three women (mean age, 50 years; range, 33-70 years) were included. Correlation between tumor uptake values measured with PET/MRI and PET/CT was strong (r s = 0.95-0.98). No difference existed between modalities for tumor maximum SUV (SUVmax) normalized to normal breast tissue SUVmean (normSUVmax) (P = .58). The least amount of measurement bias was observed with normSUVmax, +3.86% (95% limits of agreement: -28.92, +36.64).

Conclusion

These results demonstrate measurement agreement between PET/CT, the current reference standard for tumor glucose uptake quantification, and simultaneous time-of-flight breast 18F-FDG PET/MRI.Keywords: Breast, Comparative Studies, PET/CT, PET/MR Supplemental material is available for this article. © RSNA, 2021See also the commentary by Mankoff and Surti in this issue.

Fast acquisition with seamless stage translation (FASST) for a trimodal x-ray breast imaging system

PURPOSE

A major technical obstacle to bringing x-ray multicontrast (i.e., attenuation, phase, and dark-field) imaging methodology to clinical use is the prolonged data acquisition time caused by the phase stepping procedure. The purpose of this work was to introduce a fast acquisition with seamless stage translation (FASST) technique to a prototype multicontrast breast imaging system for reduced image acquisition time that is clinically acceptable.

METHODS

The prototype system was constructed based on a Hologic full-field digital mammography + digital breast tomosynthesis combination system. During each FASST acquisition process, a motorized stage holding a diffraction grating travels continuously with a constant velocity, and a train of 15 short x-ray pulses (35 ms each) was delivered by using the Zero-Degree Tomo mode of the Hologic system. Standard phase retrieval was applied to the 15 subimages without spatial interpolation to avoid spatial resolution loss. The method was evaluated using a physical phantom, a bovine udder specimen, and a freshly resected mastectomy specimen. The FASST technique was experimentally compared with single-shot acquisition methods and the standard phase stepping method.

RESULTS

The image acquisition time of the proposed method is 3.7 s. In comparison, conventional phase stepping took 105 s using the same prototype imaging system. The mean glandular dose of both methods was matched at 1.3 mGy. No artifacts or spatial resolution loss was observed in images produced by FASST. In contrast, the single-shot methods led to spatial resolution loss and residual moiré artifacts.

CONCLUSIONS

The FASST technique reduces the data acquisition time of the prototype multicontrast x-ray breast imaging system to 3.7 s, such that it is comparable to a clinical digital breast tomosynthesis exam.

Longitudinal Molecular Imaging of Progesterone Receptor Reveals Early Differential Response to Endocrine Therapy in Breast Cancer with an Activating ESR1 Mutation

Activating mutations in the estrogen receptor (ER) α-gene (ESR1) result in constitutive transcriptional activity in the absence of estrogen and are associated with endocrine resistance in metastatic ER-positive (+) breast cancer. It is not known how activating ESR1 mutations may alter the predictive values of molecular imaging agents for endocrine therapy response. This study investigated the effect of an activating ESR1 mutation on pretreatment ¹⁸F-fluoroestradiol (¹⁸F-FES) uptake and early assessment of endocrine therapy response using ¹⁸F-FDG and ¹⁸F-fluorofuranylnorprogesterone (¹⁸F-FFNP) PET/CT imaging of tumor glucose metabolism and progesterone receptor (PR) expression, respectively. Methods: ER+, PR+ T47D breast cancer cells expressing wild-type (WT) ER or an activating ESR1 mutation, Y537S-ER, were used to generate tumor xenografts in ovariectomized female immunodeficient mice supplemented with 17β-estradiol. Tumor growth curves were determined in the presence or absence of estrogen and for ethanol vehicle control or fulvestrant treatment, a selective ER degrader. Pretreatment ¹⁸F-FES uptake was compared between Y537S-ER and WT-ER tumors. Longitudinal PET/CT imaging with ¹⁸F-FFNP and ¹⁸F-FDG was performed before and 7-9 d after the start of endocrine therapy with fulvestrant. Radiopharmaceutical uptake in Y537S-ER and WT-ER tumors was compared between baseline and follow-up scans. Statistical significance was determined using paired t testing for longitudinal imaging and 2-way ANOVA for the ¹⁸F-FFNP tissue biodistribution assay. Results: Y537S-ER xenografts showed estrogen-independent growth, whereas WT-ER tumors grew only with estrogen. Fulvestrant treatment for 28 d significantly reduced tumor volumes for WT-ER but only stabilized volumes for Y537S-ER. Baseline ¹⁸F-FES uptake did not significantly differ between WT-ER and Y537S-ER tumors. Fulvestrant treatment induced a similar early metabolic response for both WT-ER and Y537S-ER tumors. ¹⁸F-FFNP uptake in WT-ER tumors was significantly reduced after 7 d of fulvestrant treatment; however, this reduction did not occur in Y537S-ER tumors, which showed no significant change between baseline and follow-up PET/CT. Conclusion: Molecular imaging of PR expression dynamics could be a noninvasive approach for early identification of reduced effectiveness of endocrine therapy resulting from activating ESR1 mutations.

Image-based screening for men at high risk for breast cancer: Benefits and drawbacks

Male breast cancer is a rare malignancy. Due to low prevalence and limited data to support male breast cancer screening, there are currently no recommendations for image-based screening in asymptomatic men and few recommendations for men at high risk for breast cancer. However, symptomatically diagnosed cancers in men are typically advanced, suggesting that earlier detection may improve outcomes. In this article we briefly review the risk factors for male breast cancer, and discuss the potential benefits and possible drawbacks of routine image-based screening for men at high risk for breast cancer.

Progesterone Receptor Gene Variants in Metastatic Estrogen Receptor Positive Breast Cancer

Tumor mutations in the gene encoding estrogen receptor alpha (ESR1) have been identified in metastatic breast cancer patients with endocrine therapy resistance. However, relatively little is known about the occurrence of mutations in the progesterone receptor (PGR) gene in this population. The study objective was to determine the frequency and prognostic significance of tumor PGR mutations for patients with estrogen receptor (ER)-positive metastatic breast cancer. Thirty-five women with metastatic or locally recurrent ER+ breast cancer were included in this IRB-approved, retrospective study. Targeted next-generation sequencing of the PGR gene was performed on isolated tumor DNA. Associations between mutation status and clinicopathologic factors were analyzed as well as overall survival (OS) from time of metastatic diagnosis. The effect of the PGR variant Y890C (c.2669A>G) identified in this cohort on PR transactivation function was tested using ER-PR- (MDA-MB-231), ER+PR+ (T47D), and ER+PR- (T47D PR KO) breast cancer cell lines. There were 71 occurrences of protein-coding PGR variants in 67% (24/36; 95% CI 49-81%) of lesions. Of the 49 unique variants, 14 are single nucleotide polymorphisms (SNPs). Excluding SNPs, the median OS of patients with PGR variants was 32 months compared to 79 months with wild-type PGR (p = 0.42). The most frequently occurring (4/36 lesions) non-SNP variant was Y890C. Cells expressing Y890C had reduced progestin-stimulated PR transactivation compared to cells expressing wild-type PR. PGR variants occur frequently in ER+ metastatic breast cancer. Although some variants are SNPs, others are predicted to be functionally deleterious as demonstrated with Y890C PR.

Recent Advances in Imaging Steroid Hormone Receptors in Breast Cancer

Estrogen receptor (ER) and progesterone receptor (PR) are important prognostic and predictive biomarkers in breast cancer. PET using ER- and PR-specific radioligands enables a whole-body, noninvasive assessment of receptor expression. Recent investigations of ER imaging with ¹⁸F-fluoroestradiol have focused on diagnosing ER-positive metastatic disease, optimizing ER-targeted drug dosage, and predicting endocrine therapy benefit. Studies of PR imaging with ¹⁸F-fluorofuranyl norprogesterone have investigated how imaging changes in PR expression as a downstream target of ER activation may reflect an early response to ER-targeted therapy. This focused review highlights recent achievements in preclinical and clinical imaging of ER and PR in breast cancer.

18F-Fluoroestradiol PET Imaging of Activating Estrogen Receptor-α Mutations in Breast Cancer

The purpose of this study was to determine the effect of estrogen receptor-α gene (ESR1) mutations at the tyrosine (Y) 537 amino acid residue within the ligand binding domain on ¹⁸F-fluoroestradiol (¹⁸F-FES) binding and in vivo tumor uptake compared with wild-type (WT)-estrogen receptor α (ER). Methods: ER-negative MDA-MB-231 breast cancer cells were used to generate stable cell lines that express WT-ER, Y537S, or Y537C mutant ER. Receptor expression and localization were confirmed by Western blot and immunofluorescence, respectively. ER transcriptional function was measured using an estrogen response element-luciferase reporter gene assay and quantitative polymerase chain reaction analysis of ER-regulated endogenous target genes. Saturation binding and competition assays were performed to determine equilibrium dissociation constant (K_d) and half maximal inhibitory concentration (IC50) values. ¹⁸F-FES uptake was measured in tumor xenografts grown in female athymic nude mice by small-animal PET/CT imaging and tissue biodistribution using 5.55 MBq (150 μCi) of ¹⁸F-FES. A 10-fold-lower injected dose of 0.555 MBq (15 μCi) of ¹⁸F-FES was also used for tissue biodistribution. Statistical significance was determined using ANOVA. Results: Y537S and Y537C mutations resulted in increased ER transcriptional activity in the absence of estrogen compared with WT-ER (11.48 ± 2.42 fold; P = 0.0002, and 5.89 ± 0.94 fold; P = 0.04, respectively). Constitutive ER activation of two target genes (PGR and TFF1) in the absence of estrogen was also observed in Y537S- and Y537C-ER cells compared with WT-ER. K_d values for ¹⁸F-FES were 0.98 ± 0.54 nM for Y537S-ER (P = 0.27) and 0.24 ± 0.03 nM for Y537C-ER (P = 0.95) compared with 0.07 ± 0.03 nM for WT-ER. IC50 values were 0.22 ± 0.09 nM for Y537S-ER (P = 0.97), 0.18 ± 0.09 nM for Y537C-ER (P = 0.99), and 0.19 ± 0.11 nM for WT-ER. Tumor xenografts expressing Y537S-ER (mean percentage injected dose per gram, 1.45 ± 0.06; P = 0.77) and Y537C-ER (2.09 ± 0.20; P = 0.21) had similar ¹⁸F-FES uptake compared with WT-ER (1.68 ± 0.12). Comparable ¹⁸F-FES uptake between Y537S-, Y537C-, and WT-ER xenografts was also observed using a 10-fold-lower injected dose with the tissue biodistribution assay. Conclusion: Since tumoral uptake of ¹⁸F-FES is not significantly impacted by Y537S-ER or Y537C-ER mutations, the potential diagnostic utility of ¹⁸F-FES PET imaging is expected to be equally valid for patients with or without these activating ESR1 mutations.

Sensitivity and Isoform Specificity of 18F-Fluorofuranylnorprogesterone for Measuring Progesterone Receptor Protein Response to Estradiol Challenge in Breast Cancer

The purpose of this study was to evaluate the ability of 21-¹⁸F-fluoro-16α,17α-[(R)-(1'-α-furylmethylidene)dioxy]-19-norpregn-4-ene-3,20-dione (¹⁸F-FFNP) to measure alterations in progesterone receptor (PR) protein level and isoform expression in response to estradiol challenge. Methods: T47D human breast cancer cells and female mice-bearing T47D tumor xenografts were treated with 17β-estradiol (E2) to increase PR expression. ¹⁸F-FFNP uptake was measured using cell uptake and tissue biodistribution assays. MDA-MB-231 breast cancer clonal cell lines were generated that express the A or B isoforms of human PR. PR protein levels, transcriptional function, and subcellular localization were determined. In vitro ¹⁸F-FFNP binding was measured via saturation and competitive binding curves. In vivo ¹⁸F-FFNP uptake was measured using tumor xenografts and positron emission tomography. Statistical significance was determined using analysis of variance and t-tests. Results: After 48 and 72 h of E2, ¹⁸F-FFNP uptake in T47D cells was maximally increased compared to both vehicle and 24 h E2 treatment (p<0.0001 vs ethanol; P = 0.02 and P = 0.0002 vs 24 h for 48 and 72 h, respectively). T47D tumor xenografts in mice treated with 72 h E2 had maximal ¹⁸F-FFNP uptake compared to ethanol-treated mice (11.3±1.4 vs 5.2±0.81 %ID/g; P = 0.002). Corresponding tumor-to-muscle uptake ratios were 4.1±0.6, 3.9±0.5, and 2.3±0.4 for 48 h E2, 72 h E2, and ethanol-treated mice, respectively. There was no significant preferential ¹⁸F-FFNP binding or uptake by PR-A versus PR-B in the PR isoform-specific cell lines and tumor xenografts. Conclusion:¹⁸F-FFNP is capable of measuring estrogen-induced shifts in total PR expression in human breast cancer cells and tumor xenografts with equivalent isoform binding.

Clinical Potential of Estrogen and Progesterone Receptor Imaging

Molecular imaging using 16α-[¹⁸F]fluoro-17β-estradiol (FES) and ¹⁸F-fluoro-furanyl-norprogesterone PET can assess in vivo function of steroid hormone receptors in breast cancer. These experimental agents have been tested in many single-center clinical trials and show promise to elucidate prognosis and predict endocrine therapy response. The current multicenter trial of FES-PET imaging will help bring this radiotracer closer to clinical use. There is tremendous potential for these tracers to advance drug development, enhance understanding of estrogen receptor-positive tumor biology, and personalize treatment.

Determination of binding affinity of molecular imaging agents for steroid hormone receptors in breast cancer

16α-[¹⁸F]Fluoro-17β-estradiol ([¹⁸F]FES) and 21-[¹⁸F]-Fluoro-16α,17α-[(R)-(1'-α-furylmethylidene)dioxyl]-19-norpregn-4-ene-3,20-dione ([¹⁸F]FFNP) are being investigated as imaging biomarkers for breast cancer patients. Quantitative positron emission tomography (PET) reflects both total receptor content and binding affinity. To study factors that may alter radiopharmaceutical binding and impact PET accuracy, assays that can separate receptor amount from binding affinity are needed. The study purpose was to quantify the binding parameters of [¹⁸F]FES and [¹⁸F]FFNP in breast cancer. Estrogen receptor-alpha (ER) and progesterone receptor (PR) positive breast cancer cell lines (MCF-7 and T47D) were used to measure [¹⁸F]FES and [¹⁸F]FFNP binding parameters via saturation and competitive binding curves. The equilibrium dissociation constant (K_d) and total receptor density (B_max) were determined using nonlinear regression of the saturation binding curves. Half-maximal inhibitory concentration (IC50) was determined using nonlinear regression of the competitive binding curves. Linear correlation between increasing cell number and tracer uptake was observed for both [¹⁸F]FES and [¹⁸F]FFNP (R²=0.99 and 0.91, respectively). Using [¹⁸F]FES, the K_d for ER in MCF-7 cells was 0.13±0.02 nM with a B_max of 1901±89.3 fmol/mg protein and IC50 of 0.085 nM (95% CI: 0.069-0.104 nM). Using [¹⁸F]FFNP, the K_d for PR in T47D cells was 0.41±0.05 nM with a B_max of 1984±75.6 fmol/mg protein and IC50 of 2.6 nM (95% CI: 2.0-3.4 nM). The ligand binding function of ER and PR can be quantified using [¹⁸F]FES and [¹⁸F]FFNP and are comparable to previous studies using tritiated radioligands. [¹⁸F]FES and [¹⁸F]FFNP can be used in cell-based assays to quantify receptor-radioligand binding affinity, which cannot be obtained from a single PET examination.

Sex as a Biologic Variable in Preclinical Imaging Research: Initial Observations with 18F-FLT

The study objective was to investigate whether sex influences 3'-deoxy-3'-¹⁸F-fluorothymidine (¹⁸F-FLT) uptake and tissue distribution in mouse models of cancer. Methods:¹⁸F-FLT biodistribution was measured in 3 strains of male and female mice (129S6/SvEv, athymic nude, and BALB/c). ¹⁸F-FDG biodistribution was measured for comparison. ¹⁸F-FLT uptake was also measured in female 129S6/SvEv mice bearing estrogen-dependent SSM3 mouse mammary tumors, male athymic nude mice bearing androgen-dependent CWR22 prostate cancer xenografts, and male and female athymic nude mice bearing estrogen-independent MDA-MB-231 human breast cancer xenografts. Ki-67 expression was assayed by immunohistochemistry. PET/CT imaging was performed to visualize ¹⁸F-FLT biodistribution and to determine pharmacokinetics. Results: Greater ¹⁸F-FLT activity was observed in blood, liver, muscle, heart, kidney, and bone in female than male mice. Pharmacokinetic analysis demonstrated higher early renal ¹⁸F-FLT activity and greater accumulation of ¹⁸F-FLT in the urinary bladder in male than female mice. The differential pattern of ¹⁸F-FLT biodistribution between the sexes seen with ¹⁸F-FLT was not observed with ¹⁸F-FDG. Increased tumoral ¹⁸F-FLT uptake compared with muscle was observed in both the SSM3 mammary tumors (2.4 ± 0.17 vs. 1.6 ± 0.14 percentage injected dose [%ID]/g at 2 h after injection, P = 0.006) and the CWR22 prostate cancer xenografts (0.34 ± 0.08 vs. 0.098 ± 0.033 %ID/g at 2 h after injection, P = 0.03). However, because of higher nonspecific muscle uptake in female mice, tumor-to-muscle uptake ratios were greater for CWR22 tumors than for SSM3 tumors (4.2 ± 0.78 vs. 1.5 ± 0.049 at 2 h after injection, P = 0.008). Sex-dependent differences in ¹⁸F-FLT uptake were also observed for MDA-MB-231 xenografts (tumor-to-muscle ratio, 7.2 ± 0.9 for female vs. 16.9 ± 8.6 for male, P = 0.039). Conversely, greater tumoral Ki-67 staining was observed in female mice (71% ± 3% for female vs. 54% ± 2% for male, P = 0.009), and this finding more closely matched the relative differences in absolute ¹⁸F-FLT tumor uptake values (4.5 ± 0.99 %ID/g for female vs. 1.9 ± 0.30 %ID/g for male, P = 0.03). Conclusion: Depending on whether female or male mice are used, differences in biodistribution and nonspecific tissue uptake can adversely affect quantitative measures of ¹⁸F-FLT uptake. Thus, sex is a potential variable to consider in defining quantitative imaging metrics using ¹⁸F-FLT to assess tumor proliferation.

18F-16α-17β-Fluoroestradiol Binding Specificity in Estrogen Receptor-Positive Breast Cancer

Purpose To determine the binding specificity of ¹⁸F-16α-17β-fluoroestradiol (FES) in estrogen receptor (ER) α-positive breast cancer cells and tumor xenografts. Materials and Methods Protocols were approved by the office of biologic safety and institutional animal care and use committee. By using ER-negative MDA-MB-231 breast cancer cells, clonal lines were created that expressed either wild-type (WT; 231 WT ER) or G521R mutant ERα (231 G521R ER), which is defective in estradiol binding. ERα protein levels, subcellular localization, and transcriptional function were confirmed. FES binding was measured by using an in vitro cell uptake assay. In vivo FES uptake was measured in tumor xenografts by using small-animal positron emission tomographic/computed tomographic imaging of 24 mice (17 WT ER tumors, nine mutant G521R ER tumors, eight MDA-MB-231 tumors, and four MCF-7 ER-positive tumors). Statistical significance was determined by using Mann-Whitney (Wilcoxon rank sum) test. Results ERα transcriptional function was abolished in the mutated 231 G521R ER cells despite appropriate receptor protein expression and nuclear localization. In vitro FES binding in the 231 G521R ER cells was reduced to that observed in the parental cells. Similarly, there was no significant FES uptake in the 231 G521R ER xenografts (percent injected dose [ID] per gram, 0.49 ± 0.042), which was similar to the negative control MDA-MB-231 xenografts (percent ID per gram, 0.42 ± 0.051; P = .20) and nonspecific muscle uptake (percent ID per gram, 0.41 ± 0.0095; P = .06). Conclusion This study showed that FES retention in ER-positive breast cancer is strictly dependent on an intact receptor ligand-binding pocket and that FES binds to ERα with high specificity. These results support the utility of FES imaging for assessing tumor heterogeneity by localizing immunohistochemically ER-positive metastases that lack receptor-binding functionality. ^© RSNA, 2017 Online supplemental material is available for this article.

Screening Breast MRI Outcomes in Routine Clinical Practice: Comparison to BI-RADS Benchmarks

RATIONALE AND OBJECTIVES

The BI-RADS Atlas 5th Edition includes screening breast magnetic resonance imaging (MRI) outcome benchmarks. However, the metrics are from expert practices and clinical trials of women with hereditary breast cancer predispositions, and it is unknown if they are appropriate for routine practice. We evaluated screening breast MRI audit outcomes in routine practice across a spectrum of elevated risk patients.

MATERIALS AND METHODS

This Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study included all consecutive screening breast MRI examinations from July 1, 2010 to June 30, 2013. Examination indications were categorized as gene mutation carrier (GMC), personal history (PH) breast cancer, family history (FH) breast cancer, chest radiation, and atypia/lobular carcinoma in situ (LCIS). Outcomes were determined by pathology and/or ≥12 months clinical and/or imaging follow-up. We calculated abnormal interpretation rate (AIR), cancer detection rate (CDR), positive predictive value of recommendation for tissue diagnosis (PPV2) and biopsy performed (PPV3), and median size and percentage of node-negative invasive cancers.

RESULTS

Eight hundred and sixty examinations were performed in 566 patients with a mean age of 47 years. Indications were 367 of 860 (42.7%) FH, 365 of 860 (42.4%) PH, 106 of 860 (12.3%) GMC, 14 of 860 (1.6%) chest radiation, and 8 of 22 (0.9%) atypia/LCIS. The AIR was 134 of 860 (15.6%). Nineteen cancers were identified (13 invasive, 4 DCIS, two lymph nodes), resulting in CDR of 19 of 860 (22.1 per 1000), PPV2 of 19 of 88 (21.6%), and PPV3 of 19 of 80 (23.8%). Of 13 invasive breast cancers, median size was 10 mm, and 8 of 13 were node negative (61.5%).

CONCLUSIONS

Performance outcomes of screening breast MRI in routine clinical practice across a spectrum of elevated risk patients met the American College of Radiology Breast Imaging Reporting and Data System benchmarks, supporting broad application of these metrics. The indication of a personal history of treated breast cancer accounted for a large proportion (42%) of our screening examinations, with breast MRI performance in this population at least comparable to that of other screening indications.

Functional Estrogen Receptor Imaging Before Neoadjuvant Therapy for Primary Breast Cancer

Estrogen receptor α (ERα) is a critical prognostic and predictive biomarker in breast cancer. ERα expression is used to determine whether patients should be treated with endocrine therapy, which is designed to block ERα signaling. Endocrine therapy given for 5-10 y after surgery improves progression-free and overall survival for patients with ER-positive primary breast cancer. However, disease recurrence and development of metastatic disease can occur despite appropriate treatment with endocrine therapy. Thus, a functional test performed at the time of initial diagnosis that can identify which patients would do well with endocrine therapy alone versus those who require adjuvant chemotherapy would be impactful for improving patient outcomes.

Imaging Diagnostic and Therapeutic Targets: Steroid Receptors in Breast Cancer

Estrogen receptor alpha (ERα) and progesterone receptor (PR) are important steroid hormone receptor biomarkers used to determine prognosis and to predict benefit from endocrine therapies for breast cancer patients. Receptor expression is routinely measured in biopsy specimens using immunohistochemistry, although such testing can be challenging, particularly in the setting of metastatic disease. ERα and PR can be quantitatively assayed noninvasively with PET. This approach provides the opportunity to assess receptor expression and function in real time, within the entire tumor, and across distant sites of metastatic disease. This article reviews the current evidence of ERα and PR PET imaging as predictive and early-response biomarkers for endocrine therapy.

Influence of less than full-time or full-time on totality of training and subsequent consultant appointment in anaesthesia

Changes in medical training have increased the popularity of less than full-time training. However, there are no data on the impact on training time or consultant workforce. We reviewed a three-year cohort of trainees via the Royal College of Anaesthetist's training and recruitment databases. Eighty-eight (96%) less than full-time trainees and 677 (95%) full-time trainees were appointed to a substantive consultant post (p = 0.82). Three (3%) less than full-time trainees and 12 (2%) full-time trainees gained part-time consultant posts (p < 0.001). Average length of training (years, months, days) was 8 y, 5 m, 6 d (median (IQR [range]) 5 y, 0 m, 14 d (4 y, 11 m, 29 d - 9 y, 8 m, 3 d [4 y, 2 m, 18 d - 12 y, 0 m, 0 d]) for full-time and 10 y, 8 m, 23 d (median (IQR [range]) 7 y, 3 m, 28 d (6 y, 7 m, 24 d - 11 y, 1 m, 23 d [4 y, 11 m, 29 d - 11 y, 9 m, 10 d]) for less than full-time trainees. The average length of training for both groups is significantly longer than the seven years used in workforce planning.

Longitudinal noninvasive imaging of progesterone receptor as a predictive biomarker of tumor responsiveness to estrogen deprivation therapy

PURPOSE

To investigate whether longitudinal functional PET imaging of mammary tumors using the radiopharmaceuticals [(18)F]FDG (to measure glucose uptake), [(18)F]FES [to measure estrogen receptor (ER) levels], or [(18)F]FFNP [to measure progesterone receptor (PgR) levels] is predictive of response to estrogen-deprivation therapy.

EXPERIMENTAL DESIGN

[(18)F]FDG, [(18)F]FES, and [(18)F]FFNP uptake in endocrine-sensitive and -resistant mammary tumors was quantified serially by PET before ovariectomy or estrogen withdrawal in mice, and on days 3 and 4 after estrogen-deprivation therapy. Specificity of [(18)F]FFNP uptake in ERα(+) mammary tumors was determined by competition assay using unlabeled ligands for PgR or glucocorticoid receptor (GR). PgR expression was also assayed by immunohistochemistry (IHC).

RESULTS

The levels of [(18)F]FES and [(18)F]FDG tumor uptake remained unchanged in endocrine-sensitive tumors after estrogen-deprivation therapy compared with those at pretreatment. In contrast, estrogen-deprivation therapy led to a reduction in PgR expression and [(18)F]FFNP uptake in endocrine-sensitive tumors, but not in endocrine-resistant tumors, as early as 3 days after treatment; the changes in PgR levels were confirmed by IHC. Unlabeled PgR ligand R5020 but not GR ligand dexamethasone blocked [(18)F]FFNP tumor uptake, indicating that [(18)F]FFNP bound specifically to PgR. Therefore, a reduction in FFNP tumor to muscle ratio in mammary tumors predicts sensitivity to estrogen-deprivation therapy.

CONCLUSIONS

Monitoring the acute changes in ERα activity by measuring [(18)F]FFNP uptake in mammary tumors predicts tumor response to estrogen-deprivation therapy. Longitudinal noninvasive PET imaging using [(18)F]FFNP is a robust and effective approach to predict tumor responsiveness to endocrine treatment.