FDG-PET/CT in high-risk primary breast cancer-a prospective study of stage migration and clinical impact

Targeting breast cancer: the promise of phage-based nanomedicines

BACKGROUND

Breast cancer is a leading cause of cancer-related mortality among women worldwide, characterized by its aggressive nature, propensity for metastasis, and resistance to standard treatment modalities. Traditional therapies, including surgery, chemotherapy, and radiation, often encounter significant limitations such as systemic toxicity and lack of specificity.

OBJECTIVE

This review aims to evaluate the recent advancements in phage-based nanomedicines as a novel approach for targeted breast cancer therapy, focusing on their mechanisms of action, therapeutic benefits, and the challenges faced in clinical implementation.

METHODS

A comprehensive literature review was conducted, analyzing studies that investigate the application of bacteriophages in cancer therapy, particularly in breast cancer. The review highlights the integration of nanotechnology with phage therapy, examining the potential for enhanced targeting and reduced side effects.

RESULTS

Phage-based nanomedicines have shown promise in selectively targeting breast cancer cells while sparing healthy tissues, thereby improving therapeutic efficacy and safety profiles. The unique properties of bacteriophages, including their ability to be engineered for specific targeting and their natural ability to induce immune responses, present significant advantages over conventional treatments.

CONCLUSION

The integration of phage therapy with nanotechnology represents a promising frontier in the fight against breast cancer. This review underscores the need for continued research to address existing challenges and to explore the full potential of phage-based nanomedicines in improving patient outcomes in breast cancer treatment.

Comparative Outcomes and Toxicity in Patients With Esophageal Cancer After Trimodality Therapy With Step-and-Shoot Intensity-Modulated Radiation Therapy Versus Volumetric Modulated Arc Therapy: The MD Anderson Experience

AIMS

To evaluate outcomes and toxicity after intensity-modulated radiation therapy given as step-and-shoot (SS) or volumetric modulated arc therapy (VMAT) for patients with locally advanced esophageal cancer treated with trimodality therapy (i.e. neoadjuvant concurrent chemoradiation therapy followed by surgery).

MATERIALS AND METHODS

Patients consecutively treated with trimodality therapy including IMRT in 2001-2022 (n = 449) were retrospectively reviewed, and 106 pairs of propensity-matched SS and VMAT patients were identified. Survival, recurrence, surgery-related prognostic factors, and chemoradiation-related toxicities were evaluated between groups.

RESULTS

Baseline characteristics were balanced between both groups except for body mass index, history of other cancer, clinical disease stage, and use of induction chemotherapy. Median follow-up time was 40 months. Relative to SS, VMAT led to higher 3-year overall survival (OS; P = 0.028, hazard ratio [HR] 0.645, 95% confidence interval [CI] 0.436-0.954) but not progression-free, locoregional recurrence-free, or distant metastasis-free survival. No predictor of excellent OS by SS versus VMAT was identified in multivariable analyses. However, VMAT was associated with reduced odds of postoperative cardiac complications (P < 0.001, odds ratio [OR] 0.296, 95% CI 0.148-0.591), pulmonary complications (P = 0.048, OR 0.539, 95% CI 0.292-0.994), pathologic partial response or worse (≥10% viable cells; P = 0.003, OR 0.418, 95% CI 0.235-0.743), and positive/close margins (P = 0.023, OR 0.346, 95% CI 0.138-0.867) relative to SS. VMAT was also associated with reduced rates of chemoradiation therapy-related weight loss (33.0% versus 79.2%, P < 0.001), fatigue (40.6% versus 68.9%, P < 0.001), nausea (31.1% versus 58.5%, P < 0.001) and cardiac toxicity (0% versus 6.6%, P = 0.007) than SS.

CONCLUSION

Based on this single institution, retrospective study with a 40-month median follow-up, VMAT utilization in trimodality treatment for locally advanced esophageal cancer appears to be associated with improved OS and rates of concurrent chemoradiation therapy-related toxicity and reduced initial 12-month postoperative complications relative to SS IMRT. Multi-institutional prospective trials addressing the limitations of this study and with longer follow-ups are warranted to validate these findings.

Comparison of [18F] FDG PET/CT and [18F]FDG PET/MRI in the Detection of Distant Metastases in Breast Cancer: A Meta-Analysis

PURPOSE

This meta-analysis aims to assess and compare the diagnostic effectiveness of [18F] FDG PET/CT and [18F] FDG PET/MRI for distant metastases in breast cancer patients.

METHODS

A comprehensive search of the PubMed and Embase databases was performed to identify relevant articles until September 22, 2023. Studies were eligible to be included if they assessed the diagnostic performance of [18F] FDG PET/CT and/or [18F] FDG PET/MRI in detecting distant metastases of breast cancer patients. The DerSimonian and Laird method was used to assess sensitivity and specificity, and then transformed through the Freeman-Tukey double arcsine transformation.

RESULTS

29 articles consisting of 3779 patients were finally included in this study. The overall sensitivity of [18F] FDG PET/CT in diagnosing distant metastases of breast cancer was 0.96 (95% CI: 0.93-0.98), and the overall specificity was 0.95 (95% CI: 0.92-0.97). The overall sensitivity of [18F] FDG PET/MRI was 1.00 (95% CI: 0.97-1.00), and the specificity was 0.97 (95% CI: 0.94-1.00). The results suggested that [18F] FDG PET/CT and [18F] FDG PET/MRI appears to have similar sensitivity (P = .16) and specificity (P = .30) in diagnosing distant metastases of breast cancer.

CONCLUSIONS

The results of our meta-analysis indicated that [18F] FDG PET/CT and [18F] FDG PET/MRI in diagnosing distant metastases of breast cancer appear to have similar sensitivity and specificity. Patients who have access to only one of these modalities will not have the accuracy of their staging compromised. In clinical practice, both of these imaging techniques have their respective strengths and limitations, and physicians should take these into account when making the most suitable choice for patients.

Guidance for Canadian Breast Cancer Practice: National Consensus Recommendations for Clinical Staging of Patients Newly Diagnosed with Breast Cancer

The accurate staging of breast cancer is fundamental for guiding treatment decisions and predicting patient outcomes. However, there can be considerable variation in routine clinical practice based on individual interpretation of guidelines and depending on the healthcare provider initially involved in working up patients newly diagnosed with breast cancer, ranging from primary care providers, triage nurses, surgeons, and/or oncologists. The optimal approach for clinical staging, particularly in asymptomatic patients presenting with intermediate-risk disease, remains a topic of dialogue among clinicians. Given this area of uncertainty, the Research Excellence, Active Leadership (REAL) Canadian Breast Cancer Alliance conducted a modified Delphi process to assess the level of agreement among Canadian expert clinicians on various staging recommendations. In total, 20 items were drafted covering staging based on biological status, the utilization of localization clips, both for the axilla during diagnosis and primary surgical site for margins and radiation therapy planning, and the use of advanced imaging for the investigation of distant metastases. Overall, the consensus threshold among all participants (i.e., ≥75% agreement) was reached in 20/20 items. Differences in clinical practice and recent findings from the literature are provided in the discussion. These consensus recommendations are meant to help standardize breast cancer staging practices in Canada, ensuring accurate diagnosis and optimal treatment planning.

18F-FDG-PET/CT in breast cancer imaging: Restaging and Implications for treatment decisions in a clinical practice setting

BACKGROUND AND PURPOSE

Although the diagnostic accuracy of 18F-fluorodeoxyglucose - positron emission tomography/computed tomography (18F-FDG-PET/CT) for breast cancer (BC) has been well studied, few studies have evaluated the impact of 18F-FDG-PET/CT on BC patient care. This study aimed to investigate restaging and 18F-FDG-PET/CT-induced changes in clinical decision-making in patients with BC.

MATERIAL AND METHODS

We retrospectively evaluated 18F-FDG-PET/CT-scans performed for BC-related indications in a prospectively collected consecutive cohort of adult patients at Skane University Hospital, Sweden. Patients with all BC stages were included and divided into three groups based on the indication for 18F-FDG-PET/CT: Group A (primary staging), Group B (response evaluation), and Group C (recurrence). The impact of 18F-FDG-PET/CT-scans on clinical management was categorized as no change, minor change (e.g. modification of treatment plans), or major change (e.g. shift from curative to palliative treatment intention).

RESULTS

A total of 376 scans (151 patients) were included: Group A 9.3% (35 of 376 scans), Group B 77.4% (291 of 376 scans), and Group C 13.3% (50 of 376 scans). Significant stage migration, predominantly upstaging, occurred in Group A (45.7%) and Group C (28.0%). Changes in clinical management were observed in 120 scans (31.9%), of which 66 were major and 54 were minor. The largest proportion of 18F-FDG-PET/CT-induced management changes were observed in Group A (57.1%), most commonly a shift from curative to palliative treatment intention due to upstaging.

INTERPRETATION

Our study indicates the clinical utility of 18F-FDG-PET/CT in BC restaging and changes in clinical management; the latter observed in approximately one-third of all cases.

Clinical implications of non-breast cancer related findings on FDG-PET/CT scan prior to neoadjuvant chemotherapy in patients with breast cancer

PURPOSE

Breast cancer (BC) patients undergoing FDG-PET/CT scans for neoadjuvant chemotherapy (NAC) may have additional non-BC related findings. The aim of this study is to describe the clinical implications of these findings.

METHODS

We included BC patients who underwent an FDG-PET/CT scan in our institute between 2011-2020 prior to NAC. We focused on patients with an additional non-BC related finding (i.e. BC metastases were excluded) for which diagnostic work-up was performed. Information about the diagnostic work-up and the clinical consequences was retrospectively gathered. A revision of all FDG-PET/CT scans was conducted by an independent physician to assess the suspicion level of the additional findings.

RESULTS

Of the 1337 patients who underwent FDG-PET/CT, 202 patients (15%) had an non-BC related additional finding for which diagnostic work-up was conducted, resulting in 318 examinations during the first year. The non-BC related findings were mostly detected in the endocrine region (26%), gastro-intestinal region (16%), or the lungs (15%). Seventeen patients (17/202: 8%, 17/1337: 1.3%) had a second primary malignancy. Only 8 patients (8/202: 4%, 8/1337: 0.6%) had a finding that was considered more prognosis-determining than their BC disease. When revising all FDG-PET/CT scans, 57 (202/57: 28%) of the patients had an additional finding categorized as low suspicious, suggesting no indication for diagnostic work-up.

CONCLUSION

FDG-PET/CT scans used for dissemination imaging in BC patients detect a high number of non-BC related additional findings, often clinically irrelevant and causing a large amount of unnecessary work-up. However, in 8% of the patients undergoing diagnostic work-up for an additional finding, a second primary malignancy was detected, warranting diagnostic attention in selected patients.

Joint EANM-SNMMI guideline on the role of 2-[18F]FDG PET/CT in no special type breast cancer : (endorsed by the ACR, ESSO, ESTRO, EUSOBI/ESR, and EUSOMA)

INTRODUCTION

There is much literature about the role of 2-[18F]FDG PET/CT in patients with breast cancer (BC). However, there exists no international guideline with involvement of the nuclear medicine societies about this subject.

PURPOSE

To provide an organized, international, state-of-the-art, and multidisciplinary guideline, led by experts of two nuclear medicine societies (EANM and SNMMI) and representation of important societies in the field of BC (ACR, ESSO, ESTRO, EUSOBI/ESR, and EUSOMA).

METHODS

Literature review and expert discussion were performed with the aim of collecting updated information regarding the role of 2-[18F]FDG PET/CT in patients with no special type (NST) BC and summarizing its indications according to scientific evidence. Recommendations were scored according to the National Institute for Health and Care Excellence (NICE) criteria.

RESULTS

Quantitative PET features (SUV, MTV, TLG) are valuable prognostic parameters. In baseline staging, 2-[18F]FDG PET/CT plays a role from stage IIB through stage IV. When assessing response to therapy, 2-[18F]FDG PET/CT should be performed on certified scanners, and reported either according to PERCIST, EORTC PET, or EANM immunotherapy response criteria, as appropriate. 2-[18F]FDG PET/CT may be useful to assess early metabolic response, particularly in non-metastatic triple-negative and HER2+ tumours. 2-[18F]FDG PET/CT is useful to detect the site and extent of recurrence when conventional imaging methods are equivocal and when there is clinical and/or laboratorial suspicion of relapse. Recent developments are promising.

CONCLUSION

2-[18F]FDG PET/CT is extremely useful in BC management, as supported by extensive evidence of its utility compared to other imaging modalities in several clinical scenarios.

PET Molecular Imaging in Breast Cancer: Current Applications and Future Perspectives

Positron emission tomography (PET) plays a crucial role in breast cancer management. This review addresses the role of PET imaging in breast cancer care. We focus primarily on the utility of 18F-fluorodeoxyglucose (FDG) PET in staging, recurrence detection, and treatment response evaluation. Furthermore, we delve into the growing interest in precision therapy and the development of novel radiopharmaceuticals targeting tumor biology. This includes discussing the potential of PET/MRI and artificial intelligence in breast cancer imaging, offering insights into improved diagnostic accuracy and personalized treatment approaches.

Treatment and survival of patients diagnosed with high-risk HR+/HER2- breast cancer in the Netherlands: a population-based retrospective cohort study

BACKGROUND

Several factors may increase the risk of recurrence of patients diagnosed with hormone receptor-positive human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer (BC). We aim to determine the proportion of patients with high-risk HR+/HER2- BC within the total HR+/HER2- BC cohort and compare their systemic treatments and survival rates with those of patients with low- and intermediate-risk HR+/HER2- BC and triple-negative (TN) BC.

PATIENTS AND METHODS

Women diagnosed with nonmetastatic invasive HR+/HER2- BC and TNBC in the Netherlands between 2011 and 2019 were identified from the Netherlands Cancer Registry. Patients with HR+/HER2- BC were categorised according to risk profile, defined by nodal status, tumour size, and histological grade. High-risk HR+/HER2- BC was defined by either four or more positive lymph nodes or one to three positive lymph nodes with a tumour size of ≥5 cm or a histological grade 3 tumour. Overall survival (OS) and relative survival (RS) were calculated using the Kaplan-Meier and Pohar-Perme method.

RESULTS

In this study of 87 455 patients with HR+/HER2- BC, 44 078 (50%) patients were diagnosed with low risk, 28 452 (33%) with intermediate risk, and 11 285 (13%) with high-risk HR+/HER2- BC. In 3640 (4%) patients, the risk profile could not be defined. Endocrine therapy and chemotherapy were used in 38% and 7% of low-risk, 90% and 47% of intermediate-risk, and 94% and 73% of high-risk patients, respectively. The 10-year OS and RS rates were 84.1% [95% confidence interval (95% CI) 83.5% to 84.7%] and 98.7% (95% CI 97.3% to 99.4%) in low-risk, 75.1% (95% CI 74.2% to 76.0%) and 91.7% (95% CI 89.7% to 93.3%) in intermediate-risk, and 63.4% (95% CI 62.0% to 64.7%) and 72.3% (70.1% to 74.3%) in high-risk patients. The 10-year OS and RS rates of 12 689 patients with TNBC were 69.7% (95% CI 68.6% to 70.8%) and 79.1% (95% CI 77.0% to 80.9%), respectively.

CONCLUSION

The poor prognosis of patients with high-risk HR+/HER2- BC highlights the need for a better acknowledgement of this subgroup and supports ongoing clinical trials aimed at optimising systemic therapy.

Women's Health Update: Growing Role of PET for Patients with Breast Cancer

Positron Emission Tomography (PET) has been growing in usage for patients with breast cancer, due to an increased number of FDA-approved PET radiotracers pertinent to patients with breast cancer as well as increased prospective evidence for the value of these agents. The leading PET radiotracer for patients with breast cancer is 18F-fluorodeoxyglucose (18F-FDG), which measures glucose metabolism. There is prospective evidence for the use of 18F-FDG PET in systemic staging of newly diagnosed locally advanced breast cancer (stages IIB-IIIC), monitoring breast cancer treatment response, and detecting breast cancer recurrence, particularly in no special type (NST) breast cancer. 16α-18F-fluoro-17β-Fluoroestradiol (18F-FES) is a radiolabeled estrogen which evaluates estrogen receptor (ER) accessible for estrogen binding. There is prospective evidence supporting 18F-FES PET as a predictive biomarker for selecting patients with metastatic breast cancer for endocrine therapies. 18F-FES PET has also been shown to be valuable in the evaluation of ER status of lesions which are difficult to biopsy, for evaluation of ER status in lesions that are equivocal on other imaging modalities, and for selecting optimal dosage of novel ER-targeted systemic therapies in early clinical trials. Multiple investigators have suggested 18F-FES PET will have an increasing role for patients with invasive lobular breast cancer (ILC), which is less optimally evaluated by 18F-FDG PET. Sodium 18F-Fluoride (18F-NaF) evaluates bone turnover and has been effective in evaluation of malignancies which commonly metastasize to bone. In patients with metastatic breast cancer, 18F-NaF PET/CT has demonstrated superior sensitivity for osseous metastases than 99mTc-MDP or CT. In addition to these three FDA-approved PET radiotracers, there are multiple novel radiotracers currently in clinical trials with potential to further increase PET usage for patients with breast cancer.

Current Role and Future Prospects of Positron Emission Tomography (PET)/Computed Tomography (CT) in the Management of Breast Cancer

Breast cancer has become the most diagnosed cancer in women globally, with 2.3 million new diagnoses each year. Accurate early staging is essential for improving survival rates with metastatic spread from loco regional to distant metastasis, decreasing mortality rates by 50%. Current guidelines do not advice the routine use of positron emission tomography (PET)-computed tomography (CT) in the staging of early breast cancer in the absence of symptoms. However, there is a growing body of evidence to suggest that the use of PET-CT in this early stage can benefit the patient by improving staging and as a result treatment and outcomes, as well as psychological burden, without increasing costs to the health service. Ongoing research in PET radiomics and artificial intelligence is showing promising future prospects in its use in diagnosis, staging, prognostication, and assessment of responses to the treatment of breast cancer. Furthermore, ongoing research to address current limitations of PET-CT by improving techniques and tracers is encouraging. In this narrative review, we aim to evaluate the current evidence of the usefulness of PET-CT in the management of breast cancer in different settings along with its future prospects, including the use of artificial intelligence (AI), radiomics, and novel tracers.

Impact of Imaging Biomarkers and AI on Breast Cancer Management: A Brief Review

Breast cancer stands out as the most frequently identified malignancy, ranking as the fifth leading cause of global cancer-related deaths. The American College of Radiology (ACR) introduced the Breast Imaging Reporting and Data System (BI-RADS) as a standard terminology facilitating communication between radiologists and clinicians; however, an update is now imperative to encompass the latest imaging modalities developed subsequent to the 5th edition of BI-RADS. Within this review article, we provide a concise history of BI-RADS, delve into advanced mammography techniques, ultrasonography (US), magnetic resonance imaging (MRI), PET/CT images, and microwave breast imaging, and subsequently furnish comprehensive, updated insights into Molecular Breast Imaging (MBI), diagnostic imaging biomarkers, and the assessment of treatment responses. This endeavor aims to enhance radiologists' proficiency in catering to the personalized needs of breast cancer patients. Lastly, we explore the augmented benefits of artificial intelligence (AI), machine learning (ML), and deep learning (DL) applications in segmenting, detecting, and diagnosing breast cancer, as well as the early prediction of the response of tumors to neoadjuvant chemotherapy (NAC). By assimilating state-of-the-art computer algorithms capable of deciphering intricate imaging data and aiding radiologists in rendering precise and effective diagnoses, AI has profoundly revolutionized the landscape of breast cancer radiology. Its vast potential holds the promise of bolstering radiologists' capabilities and ameliorating patient outcomes in the realm of breast cancer management.

The Pattern of Metastatic Breast Cancer: A Prospective Head-to-Head Comparison of [18F]FDG-PET/CT and CE-CT

The study aimed to compare the metastatic pattern of breast cancer and the intermodality proportion of agreement between [18F]FDG-PET/CT and CE-CT. Women with metastatic breast cancer (MBC) were enrolled prospectively and underwent a combined [18F]FDG-PET/CT and CE-CT scan to diagnose MBC. Experienced nuclear medicine and radiology physicians evaluated the scans blinded to the opposite scan results. Descriptive statistics were applied, and the intermodality proportion of agreement was used to compare [18F]FDG-PET/CT and CE-CT. In total, 76 women with verified MBC were enrolled in the study. The reported number of site-specific metastases for [18F]FDG-PET/CT vs. CE-CT was 53 (69.7%) vs. 44 (57.9%) for bone lesions, 31 (40.8%) vs. 43 (56.6%) for lung lesions, and 16 (21.1%) vs. 23 (30.3%) for liver lesions, respectively. The proportion of agreement between imaging modalities was 76.3% (95% CI 65.2-85.3) for bone lesions; 82.9% (95% CI 72.5-90.6) for liver lesions; 57.9% (95% CI 46.0-69.1) for lung lesions; and 59.2% (95% CI 47.3-70.4) for lymph nodes. In conclusion, bone and distant lymph node metastases were reported more often by [18F]FDG-PET/CT than CE-CT, while liver and lung metastases were reported more often by CE-CT than [18F]FDG-PET/CT. Agreement between scans was highest for bone and liver lesions and lowest for lymph node metastases.

Influence of [18F]FDG-PET/CT on Clinical Management Decisions in Breast Cancer Patients-A PET/CT Registry Study

There is a lack of evidence regarding the clinical impact of [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT, hereinafter referred to as PET/CT), especially regarding management changes and their link to overall survival. We analyzed 52 PET/CTs in 47 stage I-IV breast cancer patients, selected from a prospective oncological PET/CT registry. Indications for PET/CT were primary staging (n = 15), restaging (n = 17), and suspected recurrence (n = 20). PET/CT-induced management changes were categorized as major or minor. PET/CT-induced management changes in 41 of 52 scans (78.8%; 38 of 47 patients (80.9%)), of which major changes were suggested in 18 of 52 scans (34.6%, 17 of 47 patients, 36.2%). PET/CT downstaged 6 of 15 primary staging patients, excluding distant metastases. Major management changes were documented in 3 of 17 restaging exams. PET/CT ruled out clinically suspected recurrence in 6 of 20 cases and confirmed it in 11 of 20. In three cases, locoregional recurrence had already been diagnosed via biopsy. In 30 of 52 exams, additional diagnostic tests were avoided, of which 13 were invasive. PET/CT-based management changes resulted in a 5-year survival rate of 72.3% for the whole study group, 93.3% for the staging group, 53.8% for the restaging group, and 68.4% for the recurrence group. This study shows that PET/CT significantly impacts clinical management decisions in breast cancer patients in different clinical scenarios, potentially determining the patient's tumor stage as the basis for further therapy more reliably and by avoiding unnecessary diagnostic tests.

2-[18F]FDG-PET/CT is a better predictor of survival than conventional CT: a prospective study of response monitoring in metastatic breast cancer

This study aimed to compare CE-CT and 2-[¹⁸F]FDG-PET/CT for response monitoring metastatic breast cancer (MBC). The primary objective was to predict progression-free and disease-specific survival for responders vs. non-responders on CE-CT and 2-[¹⁸F]FDG-PET/CT. The secondary objective was to assess agreement between response categorization for the two modalities. Treatment response in women with MBC was monitored prospectively by simultaneous CE-CT and 2-[¹⁸F]FDG-PET/CT, allowing participants to serve as their own controls. The standardized response evaluation criteria in solid tumors (RECIST 1.1) and PET response criteria in solid tumors (PERCIST) were used for response categorization. For prediction of progression-free and disease-specific survival, treatment response was dichotomized into responders (partial and complete response) and non-responders (stable and progressive disease) at the first follow-up scan. Progression-free survival was defined as the time from baseline until disease progression or death from any cause. Disease-specific survival was defined as the time from baseline until breast cancer-specific death. Agreement between response categorization for both modalities was analyzed for all response categories and responders vs. non-responders. At the first follow-up, tumor response was reported more often by 2-[¹⁸F]FDG-PET/CT than CE-CT, with only fair agreement on response categorization between the two modalities (weighted Kappa 0.28). Two-year progression-free survival for responders vs. non-responders by CE-CT was 54.2% vs. 46.0%, compared with 59.1% vs. 14.3% by 2-[¹⁸F]FDG-PET/CT. Correspondingly, 2-year disease-specific survival were 83.3% vs. 77.8% for CE-CT and 84.6% vs. 61.9% for 2-[¹⁸F]FDG-PET/CT. Tumor response on 2-[¹⁸F]FDG-PET/CT was significantly associated with progression-free (HR: 3.49, P < 0.001) and disease-specific survival (HR 2.35, P = 0.008), while no association was found for tumor response on CE-CT. In conclusion, 2-[¹⁸F]FDG-PET/CT appears a better predictor of progression-free and disease-specific survival than CE-CT when used to monitor metastatic breast cancer. In addition, we found low concordance between response categorization between the two modalities.

TRIAL REGISTRATION

Clinical.

TRIALS

gov. NCT03358589. Registered 30/11/2017-Retrospectively registered, http://www.

CLINICALTRIALS

gov.

Response Monitoring in Metastatic Breast Cancer: A Prospective Study Comparing 18F-FDG PET/CT with Conventional CT

This study aimed to compare contrast-enhanced CT (CE-CT) and 18F-FDG PET/CT for response monitoring in metastatic breast cancer using the standardized response evaluation criteria RECIST 1.1 and PERCIST. The objective was to examine whether progressive disease was detected systematically earlier by one of the modalities. Methods: Women with biopsy-verified metastatic breast cancer were enrolled prospectively and monitored using combined CE-CT and 18F-FDG PET/CT every 9-12 wk to evaluate response to first-line treatment. CE-CT scans and RECIST 1.1 were used for clinical decision-making without accessing the 18F-FDG PET/CT scans. At study completion, 18F-FDG PET/CT scans were unmasked and assessed according to PERCIST. Visual assessment was used if response criteria could not be applied. The modality-specific time to progression was defined as the time from the baseline scan until the first scan demonstrating progression. Paired comparative analyses for CE-CT versus 18F-FDG PET/CT were applied, and the primary endpoint was earlier detection of progression by one modality. Secondary endpoints were time to detection of progression, response categorization, visualization of changes in response over time, and measurable disease according to RECIST and PERCIST. Results: In total, 87 women were evaluable, with a median of 6 (1-11) follow-up scans. Progression was detected first by 18F-FDG PET/CT in 43 (49.4%) of 87 patients and first by CE-CT in 1 (1.15%) of 87 patients (P < 0.0001). Excluding patients without progression (n = 32), progression was seen first on 18F-FDG PET/CT in 78.2% (43/55) of patients. The median time from detection of progression by 18F-FDG PET/CT to that of CE-CT was 6 mo (95% CI, 4.3-6.4 mo). At baseline, 76 (87.4%) of 87 patients had measurable disease according to PERCIST and 51 (58.6%) of 87 patients had measurable disease according to RECIST 1.1. Moreover, 18F-FDG PET/CT provided improved visualization of changes in response over time, as seen in the graphical abstract. Conclusion: Disease progression was detected earlier by 18F-FDG PET/CT than by CE-CT in most patients, with a potentially clinically relevant median 6-mo delay for CE-CT. More patients had measurable disease according to PERCIST than according to RECIST 1.1. The magnitude of the final benefit for patients is a perspective for future research.

State of the Art in 2022 PET/CT in Breast Cancer: A Review

Molecular imaging with positron emission tomography is a powerful and well-established tool in breast cancer management. In this review, we aim to address the current place of the main PET radiopharmaceuticals in breast cancer care and offer perspectives on potential future radiopharmaceutical and technological advancements. A special focus is given to the following: the role of 18F-fluorodeoxyglucose positron emission tomography in the clinical management of breast cancer patients, especially during staging; detection of recurrence and evaluation of treatment response; the role of 16α-18Ffluoro-17β-oestradiol positron emission tomography in oestrogen receptors positive breast cancer; the promising radiopharmaceuticals, such as 89Zr-trastuzumab and 68Ga- or 18F-labeled fibroblast activation protein inhibitor; and the application of artificial intelligence.

Changing Role of PET/CT in Cancer Care With a Focus on Radiotherapy

Positron emission tomography (PET) integrated with computed tomography (CT) has brought revolutionary changes in improving cancer care (CC) for patients. These include improved detection of previously unrecognizable disease, ability to identify oligometastatic status enabling more aggressive treatment strategies when the disease burden is lower, its use in better defining treatment targets in radiotherapy (RT), ability to monitor treatment responses early and thus improve the ability for early interventions of non-responding tumors, and as a prognosticating tool as well as outcome predicting tool. PET/CT has enabled the emergence of new concepts such as radiobiotherapy (RBT), radioimmunotherapy, theranostics, and pharmaco-radiotherapy. This is a rapidly evolving field, and this primer is to help summarize the current status and to give an impetus to developing new ideas, clinical trials, and CC outcome improvements.

A role of FDG-PET/CT for response evaluation in metastatic breast cancer?

Breast cancer prognosis is steadily improving due to early detection of primary cancer in screening programs and revolutionizing treatment development. In the metastatic setting, therapy improvements render breast cancer a chronic disease. Although FDG-PET/CT has emerged as a highly accurate method for staging metastatic breast cancer, there has been no change in response evaluation methods for decades. FDG-PET/CT has proven high prognostic values in patients with metastatic breast cancer when using quantitative PET methods. It has also shown a higher predictive value than conventional CT when applying the respective response evaluation criteria, RECIST and PERCIST. Response categorization using FDG-PET/CT is more sensitive in detecting progressive and regressive disease, while conventional imaging such as CT and bone scintigraphy deem stable disease more often. These findings reflect the higher accuracy of FDG-PET/CT for response evaluation in this patient group. But does the higher accuracy of FDG-PET/CT translate into a patient benefit when implementing it for monitoring response to palliative treatment? We have evidence of survival benefit from a retrospective study indicating the superiority of using FDG-PET/CT compared with conventional imaging for response evaluation in metastatic breast cancer patients. The survival benefit seems to result from earlier detection of progression with FDG-PET/CT than conventional imaging, leading to an earlier change in treatment with potentially better efficacy of the subsequent treatment line. FDG-PET/CT can be used semiquantitatively as suggested in PERCIST. However, we still need to improve clinically applicable methods based on neural network modeling to better integrate the quantitative information in a smart and standardized way, enabling relevant comparability between scans, patients, and institutions. Such innovation is warranted to support imaging specialists in diagnostic response assessment. Prospective multicenter studies analyzing patients' survival, quality of life, societal and patient costs of replacing conventional imaging with FDG-PET/CT are needed before firm conclusions can be drawn on which type of scan to recommend in future clinical guidelines.

Locally advanced breast cancer

Locally advanced breast cancer (LABC) is defined here as inoperable breast adenocarcinoma without distant metastases. Patients with LABC require a multidisciplinary approach. Given the risk of distant metastasis, staging exams are necessary. The incidence of LABC (stages IIIB and IIIC) has decreased in recent years. LABC has rarely been investigated separately: patients with LABC have participated both in clinical trials of palliative and of neoadjuvant therapy. Most trials did not analyze responses and long-term outcomes independently; thus, the treatment of patients with LABC is extrapolated from studies of patients with less or more advanced disease. Pathologic confirmation and molecular profiling are essential for the choice of neoadjuvant chemotherapy. Preoperative endocrine therapy may be considered in certain clinical situations; the addition of a CDK4/6 inhibitor is being investigated. HER2 positive LABCs are targeted with anti-HER2 agents combined with chemotherapy. PD-1 and PD-L1 antibodies in ‘triple-negative’ LABC are promising. Excellent responses to neoadjuvant therapy enable conservative surgery in many patients; however, inflammatory breast cancer may still indicate mastectomy. Postoperative radiotherapy is usually indicated. Target volumes include breast/chest wall, axillary, supraclavicular and internal mammary nodal basins. Preoperative radiation therapy can be useful in patients without response to systemic therapies. Palliative surgery for poor responders after neoadjuvant systemic and radiation therapy can be considered. Multidisciplinary teams can optimize local control and prevent relapses. However, modest improvement in survival was achieved between 2000 and 2014 underscoring the unmet need in patients with LABC who will benefit from specific research efforts in this disease entity.

Is 18F-FDG PET/CT Beneficial for Newly Diagnosed Breast Cancer Patients With Low Proportion of ER Expression?

OBJECTIVE

It is unclear whether the receptor status of breast malignancy or the proportion of receptors expression is useful in the interpretation of 18F-FDG PET/CT. This study's purpose was to analyze whether 18F-FDG PET/CT was valuable for helping newly diagnosed breast cancer patients find suspected or unsuspected metastasis lesions based on the proportion of receptors expression.

MATERIALS AND METHODS

Eighty newly diagnosed breast cancer patients were divided into six groups, containing N0 (no extraaxillary lymph node metastasis), N1 (extraaxillary lymph node metastasis), M0 (no distant metastasis), and M1 (distant metastasis) groups, C0 (no unsuspected metastasis), and C1 (unsuspected metastasis and treatment plan changed) detected by PET/CT. The main data, including the proportion of receptors ER (estrogen receptor), PR (progesterone receptor), and Her-2 (human epidermal growth factor receptor 2) status, were extracted. Simple correlation and logistic regression were preformed to analyze the association between them.

RESULTS

Patients in N1 group had lower proportion of ER (%) and PR (%) than that in N0 group (ER: 2 [0-80] vs. 80 [15-95]; PR: 1 [0-10] vs. 20 [0-45], p<0.001). Moreover, the proportions of ER and PR were negatively correlated with N1 (ER: [r= -0.339, p= 0.002], PR: [r= -0.247, p= 0.011]) by simple correlation. Also, patients in C1 group had lower proportion of ER (%) and PR (%) than those in C0 group (ER: 10 [0-85] vs. 80 [15-90], p=0.026; PR: 1 [0-10] vs. 20 [0-70], p=0.041), while the distribution of ER and PR between M1 and M0 group had no significant difference. After the adjustment of traditional factors, the negative correlation between the proportion of ER (OR=0.986, 95% CI of OR [0.972-0.999], p=0.016) and C1 was found by logistic regression, cutoff value was 25% (ER) calculated by ROC (Receiver Operating Characteristic) curve (AUC [Area Under Curve]= 0.647, p=0.024).

CONCLUSION

The proportion of ER in newly diagnosed breast cancer was negatively correlated with unsuspected metastasis detected by 18F-FDG PET/CT. 18F-FDG PET/CT might be recommended for newly diagnosed breast cancer patients with single lesions when the ER expression proportion is less than 25% to find unsuspected metastasis lesions and to modify treatment plan contrasted with conventional imaging and clinical examination.

Diagnostic Performance of [18F]FDG PET in Staging Grade 1-2, Estrogen Receptor Positive Breast Cancer

Positron emission tomography using [¹⁸F]fluorodeoxyglucose (FDG PET) potentially underperforms for staging of patients with grade 1–2 estrogen receptor positive (ER+) breast cancer. The aim of this study was to retrospectively investigate the diagnostic accuracy of FDG PET in this patient population. Suspect tumor lesions detected on conventional imaging and FDG PET were confirmed with pathology or follow up. PET-positive lesions were (semi)quantified with standardized uptake values (SUV) and these were correlated with various pathological features, including the histological subtype. Pre-operative imaging detected 155 pathologically verified lesions (in 74 patients). A total of 115/155 (74.2%) lesions identified on FDG PET were classified as true positive, i.e., malignant (in 67 patients) and 17/155 (10.8%) lesions as false positive, i.e., benign (in 9 patients); 7/155 (4.5%) as false negative (in 7 patients) and 16/155 (10.3%) as true negative (in 14 patients). FDG PET incorrectly staged 16/70 (22.9%) patients. The FDG uptake correlated with histological subtype, showing higher uptake in ductal carcinoma, compared to lobular carcinoma (p < 0.05). Conclusion: Within this study, FDG PET inadequately staged 22.9% of grade 1–2, ER + BC cases. Incorrect staging can lead to inappropriate treatment choices, potentially affecting survival and quality of life. Prospective studies investigating novel radiotracers are urgently needed.

Benefits and harms of implementing [18F]FDG-PET/CT for diagnosing recurrent breast cancer: a prospective clinical study

Background

[¹⁸F]-fluorodeoxyglucose-positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT) has been implemented sporadically in hospital settings as the standard of care examination for recurrent breast cancer. We aimed to explore the clinical impact of implementing [¹⁸F]FDG-PET/CT for patients with clinically suspected recurrent breast cancer and validate the diagnostic accuracy.

Methods

Women with suspected distant recurrent breast cancer were prospectively enrolled in the study between September 2017 and August 2019. [¹⁸F]FDG-PET/CT was performed, and the appearance of incidental benign and malignant findings was registered. Additional examinations, complications, and the final diagnosis were registered to reflect the clinical consequence of such findings. The diagnostic accuracy of [¹⁸F]FDG-PET/CT as a stand-alone examination was analyzed. Biopsy and follow-up were used as a reference standard.

Results

[¹⁸F]FDG-PET/CT reported breast cancer metastases in 72 of 225 women (32.0%), and metastases were verified by biopsy in 52 (52/225, 23.1%). Prior probability and posterior probability of a positive test for suspected metastatic cancer and incidental malignancies were 27%/85% and 4%/20%, respectively. Suspected malignant incidental findings were reported in 46 patients (46/225, 20.4%), leading to further examinations and final detection of nine synchronous cancers (9/225, 4.0%). These cancers originated from the lung, thyroid, skin, pancreas, peritoneum, breast, kidney, one was malignant melanoma, and one was hematological cancer. False-positive incidental malignant findings were examined in 37/225 patients (16.4%), mainly in the colon (n = 12) and thyroid gland (n = 12). Ten incidental findings suspicious for benign disease were suggested by [¹⁸F]FDG-PET/CT, and further examinations resulted in the detection of three benign conditions requiring treatment. Sensitivity, specificity, and AUC-ROC for diagnosing distant metastases were 1.00 (0.93–1.0), 0.88 (0.82–0.92), and 0.98 (95% CI 0.97–0.99), respectively.

Conclusion

[¹⁸F]FDG-PET/CT provided a high posterior probability of positive test, and a negative test was able to rule out distant metastases in women with clinically suspected recurrent breast cancer. One-fifth of patients examined for incidental findings detected on [¹⁸F]FDG-PET/CT were diagnosed with clinically relevant conditions. Further examinations of false-positive incidental findings in one of six women should be weighed against the high accuracy for diagnosing metastatic breast cancer.

Trial registration Clinical.Trials.gov. NCT03358589. Registered 30 November 2017—Retrospectively registered, http://www.ClinicalTrials.gov

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00833-3.

Breast cancer: initial workup and staging with FDG PET/CT

Purpose

Precise staging is needed to plan optimal management in breast cancer. 18F-fluorodeoxyglucose positron emission tomography coupled with computed tomography (FDG-PET/CT) offers high sensitivity in detecting extra axillary lymph nodes and distant metastases. This review aims to clarify in which groups of patients staging with FDG-PET/CT would be beneficial and should be offered. We also discuss how tumor biology and breast cancer subtypes should be taken into account when interpreting FDG-PET/CT scans.

Methods

We performed a comprehensive literature review and rigorous appraisal of research studies assessing indications for FDG-PET/CT in breast cancer. This assessment regarding breast cancer served as a basis for the recommendations set by a working group of the French Society of Nuclear Medicine, in collaboration with oncological societies, for developing good clinical practice recommendations on the use of FDG-PET/CT in oncology.

Results

FDG-PET/CT is useful for initial staging of breast cancer, independently of tumor phenotype (triple negative, luminal or HER2 +) and regardless of tumor grade. Considering histological subtype, FDG-PET/CT performs better for staging invasive ductal carcinoma, although it is also helpful for staging invasive lobular carcinomas. Based on the available data, FDG-PET/CT becomes useful for staging starting from clinical stage IIB. FDG-PET/CT is possibly useful in patients with clinical stage IIA (T1N1 or T2N0), but there is not enough strong data to recommend routine use in this subgroup. For clinical stage I (T1N0) patients, staging with FDG-PET/CT offers no added value.

Conclusion

FDG-PET/CT is useful for staging patients with breast cancer, starting from clinical stage IIB.