Early detection and prediction of cardiotoxicity after radiation therapy for breast cancer: the BACCARAT prospective cohort study

Adipocyte maturation impacts daunorubicin disposition and metabolism

INTRODUCTION

Acute lymphoblastic leukaemia (ALL) is the most common type of childhood leukaemia with effective chemotherapeutic treatment. However, obesity has been associated with higher ALL chemoresistance rates and lower event-free survival rates. The molecular mechanism of how obesity promotes chemotherapy resistance is not well delineated.

OBJECTIVES

This study evaluated the effect of adipocyte maturation on sequestration and metabolism of chemotherapeutic drug daunorubicin (DNR).

METHODS

Using targeted LC-MS/MS multi-analyte assay, DNR sequestration and metabolism were studied in human preadipocyte and adipocyte cell lines, where expressions of DNR-metabolizing enzymes aldo-keto reductases (AKR) and carbonyl reductases (CBR) were also evaluated. In addition, to identify the most DNR-metabolizing AKR/CBR isoforms, recombinant human AKR and CBR enzymes were subject to DNR metabolism. The results were further validated by AKR-, CBR-specific inhibitors.

RESULTS

This report shows that adipocyte maturation upregulates expressions of AKR and CBR enzymes (by 4- to 60- folds, p < .05), which is positively associated with enhanced sequestration and metabolism of DNR in adipocytes compared to preadipocytes (by ~30%, p < .05). In particular, adipocyte maturation upregulates AKR1C3 and CBR1, which are the predominate metabolic enzyme isoforms responsible for DNR biotransformation to its metabolites.

CONCLUSION

Fat is an expandable tissue that can sequester and detoxify DNR when stimulated by obesity, likely through the upregulation of DNR-metabolizing enzymes AKR1C3 and CBR1. Our data partially explains why obese ALL patients may be more likely to become chemoresistant towards DNR, and provides evidence for potential clinical investigation targeting obesity to reduce DNR chemoresistance.

X-ray Radiotherapy Impacts Cardiac Dysfunction by Modulating the Sympathetic Nervous System and Calcium Transients

Recent epidemiological studies have shown that patients with right-sided breast cancer (RBC) treated with X-ray irradiation (IR) are more susceptible to developing cardiovascular diseases, such as arrhythmias, atrial fibrillation, and conduction disturbances after radiotherapy (RT). Our aim was to investigate the mechanisms induced by low to moderate doses of IR and to evaluate changes in the cardiac sympathetic nervous system (CSNS), atrial remodeling, and calcium homeostasis involved in cardiac rhythm. To mimic the RT of the RBC, female C57Bl/6J mice were exposed to X-ray doses ranging from 0.25 to 2 Gy targeting 40% of the top of the heart. At 60 weeks after RI, Doppler ultrasound showed a significant reduction in myocardial strain, ejection fraction, and atrial function, with a significant accumulation of fibrosis in the epicardial layer and apoptosis at 0.5 mGy. Calcium transient protein expression levels, such as RYR2, NAK, Kir2.1, and SERCA2a, increased in the atrium only at 0.5 Gy and 2 Gy at 24 h, and persisted over time. Interestingly, 3D imaging of the cleaned hearts showed an early reduction of CSNS spines and dendrites in the ventricles and a late reorientation of nerve fibers, combined with a decrease in SEMA3a expression levels. Our results showed that local heart IR from 0.25 Gy induced late cardiac and atrial dysfunction and fibrosis development. After IR, ventricular CSNS and calcium transient protein expression levels were rearranged, which affected cardiac contractility. The results are very promising in terms of identifying pro-arrhythmic mechanisms and preventing arrhythmias during RT treatment in patients with RBC.

Cancer therapy-related cardiac dysfunction after radiation therapy for breast cancer: results from the BACCARAT cohort study

BACKGROUND

Radiation therapy (RT) for breast cancer (BC) can result in subtle cardiac dysfunction that can occur early after treatment. In 2022, the European Society of Cardiology (ESC) published the first guidelines in cardio-oncology with a harmonized definition of cancer therapy-related cardiac dysfunction (CTRCD). The aim of this study was to evaluate CTRCD occurrence over 24 months of follow-up after RT in BC patients and to analyze the association with cardiac radiation exposure.

METHODS

The prospective monocentric BACCARAT study included BC patients treated with RT without chemotherapy, aged 40-75 years, with conventional and 2D Speckle tracking echocardiography performed before RT, 6 and 24 months after RT. Based on ESC cardio-oncology guidelines, CTRCD and corresponding severity were defined with left ventricle ejection fraction and global longitudinal strain decrease, occurring at 6 or 24 months after RT. Dosimetry for whole heart, left ventricle (LV) and left coronary artery (left anterior descending and circumflex arteries (CX)) was considered to evaluate the association with CTRCD, based on logistic regressions (Odds Ratio - OR and 95% confidence interval - 95%CI). Youden index based on receiver operating characteristic curve analysis was used to identify the optimal threshold of dose-volume parameters for predicting CTRCD.

RESULTS

The study included 72 BC patients with a mean age of 58 ± 8.2 years. A total of 32 (44%) patients developed CTRCD during follow-up: 20 (28%) mild CTRCD, 7 (9%) moderate CTRCD, and 5 (7%) severe CTRCD. Cardiac radiation doses were generally higher among patients with CTRCD rather than non-CTRCD. Dose-response relationships were significant for mean CX dose (OR = 2.48, 95%CI (1.12-5.51), p = 0.02) and marginally significant for V2 of LV (OR = 1.03 95%CI (1.00-1.06), p = 0.05). V2 of LV ≥ 36% and mean CX dose ≥ 1.40 Gy thresholds were determined to be optimal for predicting CTRCD.

CONCLUSION

For BC patients treated with RT without chemotherapy, CTRCD can be observed in an important proportion of the population over 24 months after treatment. Left ventricle and circumflex coronary artery exposure were found to be associated with CTRCD and could be used for the prediction of such cardiotoxicity. Further research remains needed to confirm these results.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier- NCT02605512.

Serum sSelectin-L is an early specific indicator of radiation injury

Objective

It's crucial to identify an easily detectable biomarker that is specific to radiation injury in order to effectively classify injured individuals in the early stage in large-scale nuclear accidents.

Methods

C57BL/6J mice were subjected to whole-body and partial-body γ irradiation, as well as whole-body X-ray irradiation to explore the response of serum sSelectin-L to radiation injury. Then, it was compared with its response to lipopolysaccharide-induced acute infection and doxorubicin-induced DNA damage to study the specificity of sSelectin-L response to radiation. Furthermore, it was further evaluated in serum samples from nasopharyngeal carcinoma patients before and after radiotherapy. Simulated rescue experiments using Amifostine or bone marrow transplantation were conducted in mice with acute radiation syndrome to determine the potential for establishing sSelectin-L as a prognostic marker. The levels of sSelectin-L were dynamically measured using the ELISA method.

Results

Selectin-L is mainly expressed in hematopoietic tissues and lymphatic tissues. Mouse sSelectin-L showed a dose-dependent decrease from 1 day after irradiation and exhibited a positive correlation with lymphocyte counts. Furthermore, the level of sSelectin-L reflected the degree of radiation injury in partial-body irradiation mice and in nasopharyngeal carcinoma patients. sSelectin-L was closely related to the total dose of γ or X ray. There was no significant change in the sSelectin-L levels in mice intraperitoneal injected with lipopolysaccharide or doxorubicin. The sSelectin-L was decreased slower and recovered faster than lymphocyte count in acute radiation syndrome mice treated with Amifostine or bone marrow transplantation.

Conclusions

Our study shows that sSelectin-L has the potential to be an early biomarker to classify injured individuals after radiation accidents, and to be a prognostic indicator of successful rescue of radiation victims.

Mechanisms of Cardiovascular Toxicities Induced by Cancer Therapies and Promising Biomarkers for Their Prediction: A Scoping Review

AIM

With the advancement of anti-cancer medicine, cardiovascular toxicities due to cancer therapies are common in oncology patients, resulting in increased mortality and economic burden. Cardiovascular toxicities caused by cancer therapies include different severities of cardiomyopathy, arrhythmia, myocardial ischaemia, hypertension, and thrombosis, which may lead to left ventricular dysfunction and heart failure. This scoping review aimed to summarise the mechanisms of cardiovascular toxicities following various anti-cancer treatments and potential predictive biomarkers for early detection.

METHODS

PubMed, Cochrane, Embase, Web of Science, Scopus, and CINAHL databases were searched for original studies written in English related to the mechanisms of cardiovascular toxicity induced by anti-cancer therapies, including chemotherapy, targeted therapy, immunotherapy, radiation therapy, and relevant biomarkers. The search and title/abstract screening were conducted independently by two reviewers, and the final analysed full texts achieved the consensus of the two reviewers.

RESULTS

A total of 240 studies were identified based on their titles and abstracts. In total, 107 full-text articles were included in the analysis. Cardiomyocyte and endothelial cell apoptosis caused by oxidative stress injury, activation of cell apoptosis, blocking of normal cardiovascular protection signalling pathways, overactivation of immune cells, and myocardial remodelling were the main mechanisms. Promising biomarkers for anti-cancer therapies related to cardiovascular toxicity included placental growth factor, microRNAs, galectin-3, and myeloperoxidase for the early detection of cardiovascular toxicity.

CONCLUSION

Understanding the mechanisms of cardiovascular toxicity following various anti-cancer treatments could provide implications for future personalised treatment methods to protect cardiovascular function. Furthermore, specific early sensitive and stable biomarkers of cardiovascular system damage need to be identified to predict reversible damage to the cardiovascular system and improve the effects of anti-cancer agents.

Heart and Coronary Artery Dose Sparing in Left-sided Breast Cancer: 3D-Conformal Radiotherapy vs. Helical Tomotherapy

BACKGROUND/AIM

To compare heart, left ventricle (LV) and coronary artery dose-sparing with three-dimensional conformal radiotherapy (3D-CRT) vs. helical tomotherapy (HT) in left-sided breast cancer (BC).

PATIENTS AND METHODS

3D-CRT and HT treatments were planned for 20 patients (pts). Computed tomography (CT) scans without and with intravenous contrast (ic) were performed and co-registered. Left breast and organs at risk (OARs) were contoured. Dose-volume histograms (DVHs) for 3D-CRT and HT treatment plans were evaluated in terms of planning target volume for evaluation (PTVeval) coverage and dose to the OARs.

RESULTS

HT provided the best target coverage and significantly reduced D2% and mean dose to the left anterior descending artery (LADA) and to the LADA-planning organ at risk volume (PRV), D2%, V5 and mean dose to the LV and D2% and V25 to the heart. As expected, due to the rotational delivery, the dose to all other coronary arteries and their PRV, contralateral breast and lungs was higher with HT.

CONCLUSION

In left-sided BC, HT provided the best target coverage and significantly reduced LV and LADA doses. Moreover D2% and V25 to the heart were significantly reduced. Further studies are needed to correlate dosimetric findings with in-depth cardiac monitoring.

A visualized model for identifying optimal candidates for aggressive locoregional surgical treatment in patients with bone metastases from breast cancer

Background

The impact of surgical resection of primary (PTR) on the survival of breast cancer (BC) patients with bone metastasis (BM) has been preliminarily investigated, but it remains unclear which patients are suitable for this procedure. Finally, this study aims to develop a predictive model to screen BC patients with BM who would benefit from local surgery.

Methods

BC patients with BM were identified using the Surveillance, Epidemiology, and End Results (SEER) database (2010 and 2015), and 39 patients were obtained for external validation from an Asian medical center. According to the status of local surgery, patients were divided into Surgery and Non-surgery groups. Propensity score matching (PSM) analysis was performed to reduce selection bias. Kaplan-Meier (K-M) survival and Cox regression analyses were conducted before and after PSM to study the survival difference between the two groups. The survival outcome and treatment modality were also investigated in patients with different metastatic patterns. The logistic regression analyses were utilized to determine significant surgery-benefit-related predictors, develop a screening nomogram and its online version, and quantify the beneficial probability of local surgery for BC patients with BM. Receiver operating characteristic (ROC) curves, the area under the curves (AUC), and calibration curves were plotted to evaluate the predictive performance and calibration of this model, whereas decision curve analysis (DCA) was used to assess its clinical usefulness.

Results

This study included 5,625 eligible patients, of whom 2,133 (37.92%) received surgical resection of primary lesions. K-M survival analysis and Cox regression analysis demonstrated that local surgery was independently associated with better survival. Surgery provided significant survival benefits in most subgroups and metastatic patterns. After PSM, patients who received surgery had a longer survival time (OS: 46 months vs. 32 months, p < 0.001; CSS: 50 months vs. 34 months, p < 0.001). Logistic regression analysis determined six significant surgery-benefit-related variables: T stage, radiotherapy, race, liver metastasis, brain metastasis, and breast subtype. These factors were combined to establish the nomogram and a web probability calculator (https://sunshine1.shinyapps.io/DynNomapp/), with an AUC of 0.673 in the training cohort and an AUC of 0.640 in the validation cohort. The calibration curves exhibited excellent agreement. DCA indicated that the nomogram was clinically useful. Based on this model, surgery patients were assigned into two subsets: estimated sur-non-benefit and estimated sur-benefit. Patients in the estimated sur-benefit subset were associated with longer survival (median OS: 64 months vs. 33 months, P < 0.001). Besides, there was no difference in survival between the estimated sur-non-benefit subset and the non-surgery group.

Conclusion

Our study further confirmed the significance of local surgery in BC patients with BM and proposed a novel tool to identify optimal surgical candidates.

Lipoprotein(a) in patients with breast cancer after chemotherapy: exploring potential strategies for cardioprotection

Developments in neoadjuvant and adjuvant chemotherapy (CHT) have led to an increase in the number of breast cancer survivors. The determination of an appropriate follow-up for these patients is of increasing importance. Deaths due to cardiovascular disease (CVD) are an important part of mortality in patients with breast cancer.This review suggests that chemotherapeutic agents may influence lipoprotein(a) (Lp(a)) concentrations in breast cancer survivors after CHT based on many convincing evidence from epidemiologic and observational researches. Usually, the higher the Lp(a) concentration, the higher the median risk of developing CVD. However, more clinical trial results are needed in the future to provide clear evidence of a possible causal relationship. This review also discuss the existing and emerging therapies for lowering Lp(a) concentrations in the clinical setting. Hormone replacement therapy, statins, proprotein convertase subtilisin/kexin-type 9 (PCSK9) inhibitors, Antisense oligonucleotides, small interfering RNA, etc. may reduce circulating Lp(a) or decrease the incidence of CVD.

Assessment of short-term effects of thoracic radiotherapy on the cardiovascular parasympathetic and sympathetic nervous systems

Background

Prior research suggests that cardiovascular autonomic dysfunction might be an early marker of cardiotoxicity induced by antitumor treatment and act as an early predictor of cardiovascular disease-related morbidity and mortality. The impact of thoracic radiotherapy on the parasympathetic and sympathetic nervous systems, however, remains unclear. Therefore, this study aimed to evaluate the short-term effects of thoracic radiotherapy on the autonomic nervous system, using deceleration capacity (DC), acceleration capacity (AC) of heart rate, and heart rate variability (HRV) as assessment tools.

Methods

A 5 min electrocardiogram was collected from 58 thoracic cancer patients before and after thoracic radiotherapy for DC, AC, and HRV analysis. HRV parameters employed included the standard deviation of the normal-normal interval (SDNN), root mean square of successive interval differences (RMSSD), low frequency power (LF), high frequency power (HF), total power (TP), and the LF to HF ratio. Some patients also received systemic therapies alongside radiotherapy; thus, patients were subdivided into a radiotherapy-only group (28 cases) and a combined radiotherapy and systemic therapies group (30 cases) for additional subgroup analysis.

Results

Thoracic radiotherapy resulted in a significant reduction in DC (8.5 [5.0, 14.2] vs. 5.3 [3.5, 9.4], p = 0.002) and HRV parameters SDNN (9.9 [7.03, 16.0] vs. 8.2 [6.0, 12.4], p = 0.003), RMSSD (9.9 [6.9, 17.5] vs. 7.7 [4.8, 14.3], p = 0.009), LF (29 [10, 135] vs. 24 [15, 50], p = 0.005), HF (35 [12, 101] vs. 16 [9, 46], p = 0.002), TP (74 [41, 273] vs. 50 [33, 118], p < 0.001), and a significant increase in AC (-8.2 [-14.8, -4.9] vs. -5.8 [-10.1, -3.3], p = 0.003) and mean heart rate (79.8 ± 12.6 vs. 83.9 ± 13.6, p = 0.010). Subgroup analysis indicated similar trends in mean heart rate, DC, AC, and HRV parameters (SDNN, RMSSD, LF, HF, TP) in both the radiotherapy group and the combined treatment group post-radiotherapy. No statistically significant difference was noted in the changes observed in DC, AC, and HRV between the two groups pre- and post-radiotherapy.

Conclusion

Thoracic radiotherapy may induce cardiovascular autonomic dysfunction by reducing parasympathetic activity and enhancing sympathetic activity. Importantly, the study found that the concurrent use of systemic therapies did not significantly amplify or contribute to the alterations in autonomic function in the short-term following thoracic radiotherapy. DC, AC and HRV are promising and feasible biomarkers for evaluating autonomic dysfunction caused by thoracic radiotherapy.

Early Development of Atherosclerotic Plaques in the Coronary Arteries after Radiotherapy for Breast Cancer (BACCARAT Study)

Background-Radiotherapy (RT) for breast cancer (BC) can lead to an increased risk of coronary artery disease several years after RT. The aim of this study was to evaluate the development of overall, non-calcified and calcified atherosclerotic plaques over 2 years after BC for RT and associations with cardiac exposure. Methods-The study included 101 left- or right-sided BC patients treated with RT without chemotherapy. A coronary CT angiography was performed before and 2 years after RT. Plaque development thorough the entire coronary network was defined as an increased number of plaques. Cardiac exposure was quantified with mean doses to the heart, left ventricle, and coronary arteries. Logistic regression models were used to assess association with doses. Results-At inclusion, 37% of patients had plaques, increasing to 42% two years after RT. Overall plaque development was observed in seven patients: five with calcified plaque development and four with non-calcified plaque development. The risk of overall plaque development was significantly associated with doses to the Left Main and Circumflex coronary arteries (OR at 1 Gy = 2.32, p = 0.03 and OR at 1 Gy = 2.27, p = 0.03, respectively). Specific analyses for calcified and non-calcified plaque development showed similar results. Conclusion-Our study suggests an association between coronary arteries exposure and the risk of developing both calcified and non-calcified atherosclerotic plaques over 2 years after BC RT. Trial registration number: NCT02605512.

Radiation-induced circulating microRNAs linked to echocardiography parameters after radiotherapy

Introduction

Patients treated with radiotherapy to the chest region are at risk of cardiac sequelae, however, identification of those with greatest risk of complications remains difficult. Here, we sought to determine whether short-term changes in circulating miRNA expression are related to measures of cardiac dysfunction in follow-up.

Materials and methods

Two parallel patient cohorts were enrolled and followed up for 3 years after completion of RT to treat left-sided breast cancer. In the primary group (N=28) we used a a panel of 752 miRNAs to identify miRNAs associated with radiation and cardiac indices at follow up. In the second, independent cohort (N=56) we validated those candidate miRNAs with a targeted qPCR panel. In both cohorts. serum samples were collected before RT, 24h after the last dose and 1 month after RT; cardiac echocardiography was performed 2.5-3 year after RT.

Results

Seven miRNAs in the primary group showed marked changes in serum miRNAs immediately after RT compared to baseline and associations with cardiopulmonary dose-volume histogram metrics. Among those miRNAs: miR-15b-5p, miR-22-3p, miR-424-5p and miR-451a were confirmed to show significant decrease of expression 24 hours post-RT in the validation cohort. Moreover, miR-29c, miR-451 and miR-424 were correlated with the end-diastolic diameter of the left ventricle, which was also confirmed in multivariable analysis adjusting for RT-associated factors.

Conclusion

We identified a subset of circulating miRNAs predictive for cardiac function impairment in patients treated for left-sided breast cancer, although longer clinical observation could determine if these can be used to predict major clinical endpoints.

DNA Methylation Alterations in Fractionally Irradiated Rats and Breast Cancer Patients Receiving Radiotherapy

Radiation-Induced CardioVascular Disease (RICVD) is an important concern in thoracic radiotherapy with complex underlying pathophysiology. Recently, we proposed DNA methylation as a possible mechanism contributing to RICVD. The current study investigates DNA methylation in heart-irradiated rats and radiotherapy-treated breast cancer (BC) patients. Rats received fractionated whole heart X-irradiation (0, 0.92, 6.9 and 27.6 Gy total doses) and blood was collected after 1.5, 3, 7 and 12 months. Global and gene-specific methylation of the samples were evaluated; and gene expression of selected differentially methylated regions (DMRs) was validated in rat and BC patient blood. In rats receiving an absorbed dose of 27.6 Gy, DNA methylation alterations were detected up to 7 months with differential expression of cardiac-relevant DMRs. Of those, SLMAP showed increased expression at 1.5 months, which correlated with hypomethylation. Furthermore, E2F6 inversely correlated with a decreased global longitudinal strain. In BC patients, E2F6 and SLMAP exhibited differential expression directly and 6 months after radiotherapy, respectively. This study describes a systemic radiation fingerprint at the DNA methylation level, elucidating a possible association of DNA methylation to RICVD pathophysiology, to be validated in future mechanistic studies.

Early Coronary Artery Calcification Progression over Two Years in Breast Cancer Patients Treated with Radiation Therapy: Association with Cardiac Exposure (BACCARAT Study)

Background: Radiotherapy (RT) for breast cancer (BC) can induce coronary artery disease many years after RT. At an earlier stage, during the first two years after RT, we aimed to evaluate the occurrence of increased coronary artery calcium (CAC) and its association with cardiac exposure. Methods: This prospective study included 101 BC patients treated with RT without chemotherapy. Based on CAC CT scans performed before and two years after RT, the event ‘CAC progression’ was defined by an increase in overall CAC score (CAC RT+ two years—CAC before RT > 0). Dosimetry was evaluated for whole heart, left ventricle (LV), and coronary arteries. Multivariable logistic regression models were used to assess association with doses. Results: Two years after RT, 28 patients presented the event ‘CAC progression’, explained in 93% of cases by a higher CAC score in the left anterior descending coronary (LAD). A dose−response relationship was observed with LV exposure (for Dmean LV: OR = 1.15, p = 0.04). LAD exposure marginally explained increased CAC in the LAD (for D2 LV: OR =1.03, p = 0.07). Conclusion: The risk of early CAC progression may be associated with LV exposure. This progression might primarily be a consequence of CAC increase in the LAD and its exposure.

Subclinical Left Ventricular Dysfunction Detected by Speckle-Tracking Echocardiography in Breast Cancer Patients Treated With Radiation Therapy: A Six-Month Follow-Up Analysis (MEDIRAD EARLY‐HEART study)

Background

In the case of breast cancer (BC), radiotherapy (RT) helps reduce locoregional recurrence and BC-related deaths but can lead to cardiotoxicity, resulting in an increased risk of long-term major cardiovascular events. It is therefore of primary importance to early detect subclinical left ventricular (LV) dysfunction in BC patients after RT and to determine the dose–response relationships between cardiac doses and these events.

Methods

Within the frame of the MEDIRAD European project (2017–2022), the prospective multicenter EARLY‐HEART study (ClinicalTrials.gov Identifier: NCT03297346) included chemotherapy naïve BC women aged 40–75 years and treated with lumpectomy and adjuvant RT. Myocardial strain analysis was provided using speckle‐tracking echocardiography performed at baseline and 6 months following RT. A global longitudinal strain (GLS) reduction >15% between baseline and follow-up was defined as a GLS-based subclinical LV dysfunction. Individual patient dose distributions were obtained using multi-atlas-based auto-segmentation of the heart. Dose-volume parameters were studied for the whole heart (WH) and left ventricle (LV).

Results

The sample included 186 BC women (57.5 ± 7.9 years, 64% left-sided BC). GLS-based subclinical LV dysfunction was observed in 22 patients (14.4%). These patients had significantly higher cardiac exposure regarding WH and LV doses compared to patients without LV dysfunction (for mean WH dose: 2.66 ± 1.75 Gy versus 1.64 ± 0.96 Gy, p = 0.01). A significantly increased risk of subclinical LV dysfunction was observed with the increase in the dose received to the WH [ORs from 1.13 (V₅) to 1.74 (D_mean); p <0.01] and to the LV [ORs from 1.10 (V₅) to 1.46 (D_mean); p <0.01]. Based on ROC analysis, the LV-V₅ parameter may be the best predictor of the short-term onset of subclinical LV dysfunction.

Conclusion

These results highlighted that all cardiac doses were strongly associated with the occurrence of subclinical LV dysfunction arising 6 months after BC RT. Whether measurements of GLS at baseline and 6 months after RT combined with cardiac doses can early predict efficiently subclinical events occurring 24 months after RT remains to be investigated.

Postmastectomy Radiotherapy Improves Survival Benefits in De Novo Stage IV Breast Cancer: A Propensity-Score Matched Analysis

Purpose The role of postmastectomy radiotherapy (PMRT) in patients with de novo stage IV breast cancer is unclear. This study aimed to evaluate the value of PMRT for metastatic breast cancer who underwent a modified radical mastectomy. Methods: Data on de novo stage IV breast cancer patients who received modified radical mastectomy between 2010 and 2015 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) analysis based on age, T stage, N stage, breast subtype, and chemotherapy was conducted to balance baseline clinical characteristics. The prognostic roles of PMRT on cancer-specific survival (CSS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox proportional hazard models. Results: A total of 1944 patients were enrolled before PSM. After PSM, 1458 patients were included. PMRT improved the prognosis of CSS and OS. Multivariate Cox analysis showed that PMRT was independently prognostic for CSS (HR 0.739, 95% CI. 0.619-0.884, P = 0.001) and OS (HR 0.744, 95%CI 0.628-0.8810, P = 0.001). Further subgroup analyses found that survival superiority was observed in T3-4 or N + subgroup (both P < 0.001 for CSS and OS), and Her2-/HR + breast subtype (HR 0.703, 95%CI 0.558-0.888 for CSS, and HR 0.712, 95%CI 0.573-0.885 for OS), especially in patients with bone metastasis but without brain metastasis. Conclusion: PMRT improved survival in de novo stage IV breast cancer patients in selected T3-4 or N + subgroup and Her2-/HR + breast subtype. However, these findings need to be validated by further studies before being incorporated into clinical practice.

Development of Biomarkers for Radiation Biodosimetry and Medical Countermeasures Research: Current Status, Utility, and Regulatory Pathways

Biomarkers are important indicators of biological processes in health or disease. For this reason, they play a critical role in advanced development of radiation biodosimetry tools and medical countermeasures (MCMs). They can aid in the assessment of radiation exposure level, extent of radiation-induced injury, and/or efficacy of an MCM. This meeting report summarizes the presentations and discussions from the 2020 workshop titled, "Biomarkers in Radiation Biodosimetry and Medical Countermeasures," sponsored by the Radiation and Nuclear Countermeasures Program (RNCP) at the National Institute of Allergy and Infectious Diseases (NIAID). The main goals of this meeting were to: 1. Provide an overview on biomarkers and to focus on the state of science with regards to biomarkers specific to radiation biodosimetry and MCMs; 2. Understand developmental challenges unique to the role of biomarkers in the fields of radiation biodosimetry and MCM development; and 3. Identify existing gaps and needs for translational application.

Potential role of epicardial adipose tissue as a biomarker of anthracycline cardiotoxicity

Background

We investigated the radiodensity of epicardial (EAT), subcutaneous (SAT), and visceral adipose tissue (VAT) before and after treatment with anthracyclines in a population of breast cancer (BC) patients, and in controls not treated with anthracyclines, to detect a potential role of EAT density as a biomarker of changes related to chemotherapy cardiotoxicity.

Methods

We reviewed BC patients treated with anthracyclines who underwent CT before (CT-t₀) and after (CT-t₁) chemotherapy, and age- and sex-matched controls who underwent two CT examinations at comparable intervals. On non-contrast scans, EAT was segmented contouring the pericardium and thresholding between -190 and -30 Hounsfield units (HU), and SAT and VAT were segmented with two 15-mm diameter regions of interest thresholded between -195 and -45 HU.

Results

Thirty-two female patients and 32 controls were included. There were no differences in age (p = 0.439) and follow-up duration (p = 0.162) between patients and controls. Between CT-t₀ and CT-t₁, EAT density decreased in BC patients (-66 HU, interquartile range [IQR] -71 to -63 HU, to -71 HU, IQR -75 to -66 HU, p = 0.003), while it did not vary in controls (p = 0.955). SAT density increased from CT-t₀ to CT-t₁ in BC patients (-107 HU, IQR -111 to -105 HU, to -105 HU, IQR -110 to -100 HU, p = 0.014), whereas it did not change in controls (p = 0.477). VAT density did not vary in either BC patients (p = 0.911) or controls (p = 0.627).

Conclusions

EAT density appears to be influenced by anthracycline treatment for BC, well known for its cardiotoxicity, shifting towards lower values indicative of a less active metabolism.

[Impact of thoracic irradiation on cardiac structures]

Thoracic irradiation requires protection of the heart as an organ at risk of complications. The mean heart dose is the most studied dosimetric parameter in the literature. Recent studies question its relevance in view of the multiplicity of cardiac injuries, the heterogeneity of the cardiac dose distribution and the current technical possibilities to refine cardiac dosimetric protection. The objective of this literature review is to analyze the available scientific data on the impact of the dose received by the cardiac substructures. A search of articles using the PubMed search engine was used to select the most relevant studies. A total of 19 articles were selected according to pre-established criteria to answer the issue. Several studies found significant associations between dosimetric parameters of substructures and clinical cardiological impact. Some proposed dose constraints for substructures.

Breast cancer treatment-related cardiovascular disturbances: advocacy for a watchful attitude in this never-ending story

INTRODUCTION

Thanks to the emergence of new therapeutics, prognosis and outcome of breast cancer patients (any subtype) have improved significantly. This raises the issue of the interactions and side effects related to the use of multiple drugs. Thus, to decide on a treatment, the optimal benefit risk-ratio should be carefully watched as toxicities such as cardiac ones effect on long-term survival. Indeed, nowadays in France, cardiovascular diseases rank first as causes of death in women.

AREAS COVERED

This non-exhaustive review aims to report the currently available data on cardiac side effects caused by the use of emerging drugs in breast cancer, in localized or metastatic diseases alike. We will focus on HER2-inhibitors, cyclin-dependent-kinase 4/6 and PARP inhibitors, chemotherapy and immunotherapy, before discussing the means of prevention.

EXPERT OPINION

Although this issue has largely been studied, the recent emergence of new drugs emphasizes the necessity for oncologists to adapt their practice to a multidisciplinary model that includes cardio-oncology.

Anticancer Drug-Induced Cardiotoxicity: Insights and Pharmacogenetics

The advancement in therapy has provided a dramatic improvement in the rate of recovery among cancer patients. However, this improved survival is also associated with enhanced risks for cardiovascular manifestations, including hypertension, arrhythmias, and heart failure. The cardiotoxicity induced by chemotherapy is a life-threatening consequence that restricts the use of several chemotherapy drugs in clinical practice. This article addresses the prevalence of cardiotoxicity mediated by commonly used chemotherapeutic and immunotherapeutic agents. The role of susceptible genes and radiation therapy in the occurrence of cardiotoxicity is also reviewed. This review also emphasizes the protective role of antioxidants and future perspectives in anticancer drug-induced cardiotoxicities.

Myocardial injury detected by T1 and T2 mapping on CMR predicts subsequent cancer therapy-related cardiac dysfunction in patients with breast cancer treated by epirubicin-based chemotherapy or left-sided RT

Objectives

Cancer therapy-related cardiac dysfunction (CTRCD) is a relevant clinical problem and needs early prediction. This study aimed to analyze myocardial injury using serial laboratory and cardiac magnetic resonance imaging (CMR) parameters after epirubicin-based chemotherapy compared with left-sided radiotherapy and to study their value for early prediction of CTRCD.

Methods

Sixty-six consecutive women (53 ± 13 years) including n = 39 with epirubicin-based chemotherapy and n = 27 with left-sided radiotherapy were prospectively studied by 3 T CMR including left ventricular (LV) mass and volumes for ejection fraction (LVEF), as well as feature-tracking with global longitudinal strain (GLS) and T1/T2 mapping. CMR was performed at baseline, at therapy completion (follow-up 1, FU1), and after 13 ± 2 months (FU2). CTRCD was defined as LVEF decline of at least 10% to < 55% or a > 15% GLS change at FU2.

Results

T1 and T2 increased at FU1 after epirubicin-based chemotherapy, but not after left-sided radiotherapy. CTRCD occurred in 20% of patients after epirubicin-based chemotherapy and in 4% after left-sided radiotherapy. T1 at FU1 was the best single parameter to predict CTRCD with an area under the curve (AUC) of 0.712 (CI 0.587–0.816, p = 0.005) with excellent sensitivity (100%, 66–100%), but low specificity (44%, 31–58%). Combined use of increased T1 and LVEF ≤ 60% at FU1 improved AUC to 0.810 (0.695–0.896) resulting in good sensitivity (78%, 44–95%) and specificity (84%, 72–92%).

Conclusion

Only epirubicin-based chemotherapy, but not left-sided radiotherapy, resulted in increased T1/T2 myocardial relaxation times as a marker of myocardial injury. Combined use of CMR parameters may allow an early prediction of subsequent CTCRD.

Key Points

• Myocardial T1 and T2 relaxation times increased at FU1 after epirubicin-based chemotherapy, but not after left-sided radiotherapy.

• Cancer therapy–related cardiac dysfunction (CTRCD) occurred in 20% of patients after epirubicin-based chemotherapy and in 4% after left-sided radiotherapy.

• Combined use of increased T1 and reduced LVEF had an AUC of 0.810 (0.695–0.896) to predict CTRCD with good sensitivity (78%, 44–95%) and specificity (84%, 72–92%).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08260-7.

Speckle-Tracking Echocardiography in Cardio-Oncology and Beyond

Speckle-tracking echocardiography has enabled clinicians to detect changes in myocardial function with more sensitivity than that afforded by traditional diastolic and systolic functional measurements, including left ventricular ejection fraction. Speckle-tracking echocardiography enables evaluation of myocardial strain in terms of strain (percent change in length of a myocardial segment relative to its length at baseline) and strain rate (strain per unit of time). Both measurements have potential for use in diagnosing and monitoring the cardiovascular side effects of cancer therapy. Regional and global strain measurements can independently predict outcomes not only in patients who experience cardiovascular complications of cancer and cancer therapy, but also in patients with a variety of other clinical conditions. This review and case series examine the clinical applications and overall usefulness of speckle-tracking echocardiography in cardio-oncology and, more broadly, in clinical cardiology.

New progress in elucidating the relationship between cancer therapy and cardiovascular toxicity

Onco-cardiology is an emerging field linking cancer with cardiovascular injury. Understanding the mechanism of cardiac injury helps improve the quality of life of cancer survivors. A series of studies on adverse reactions to cancer or oncological treatments has indicated that adverse cardiovascular events related to cancer treatments may occur over a longer period of survival, and even years after therapy has concluded. Current cancer therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy, have been found to have latent cardiovascular toxicity. These toxic effects are often progressive and irreversible and ultimately lead to cardiovascular events such as heart failure, hypertension, coronary heart diseases, arrhythmia, and thromboembolism. Therefore, more emphasis should be placed on revealing the mechanism of cancer treatment-related cardiovascular toxicity. This would help to guide prevention, diagnosis, and treatment of CVDs in cancer survivors.

Association of Breast Cancer Irradiation With Cardiac Toxic Effects: A Narrative Review

IMPORTANCE

To promptly recognize and manage cardiovascular (CV) risk factors before, during, and after cancer treatment, decreasing the risk of cancer therapy-related cardiac dysfunction is crucial. After recent advances in breast cancer treatment, mortality rates from cancer have decreased, and the prevalence of survivors with a potentially higher CV disease risk has increased. Cardiovascular risks might be associated with the multimodal approach, including systemic therapies and breast radiotherapy (RT).

OBSERVATIONS

The heart disease risk seems to be higher in patients with tumors in the left breast, when other classic CV risk factors are present, and when adjunctive anthracycline-based chemotherapy is administered, suggesting a synergistic association. Respiratory control as well as modern RT techniques and their possible further refinement may decrease the prevalence and severity of radiation-induced heart disease. Several pharmacological cardioprevention strategies for decreasing cardiac toxic effects have been identified in several guidelines. However, further research is needed to ascertain the feasibility of these strategies in routine practice.

CONCLUSIONS AND RELEVANCE

This review found that evidence-based recommendations are lacking on the modalities for and intensity of heart disease screening, surveillance of patients after RT, and treatment of these patients. A multidisciplinary and multimodal approach is crucial to guide optimal management.

Incorporating sensitive cardiac substructure sparing into radiation therapy planning

PURPOSE

Rising evidence suggests that cardiac substructures are highly radiosensitive. However, they are not routinely considered in treatment planning as they are not readily visualized on treatment planning CTs (TPCTs). This work integrated the soft tissue contrast provided by low-field MRIs acquired on an MR-linac via image registration to further enable cardiac substructure sparing on TPCTs.

METHODS

Sixteen upper thoracic patients treated at various breathing states (7 end-exhalation, 7 end-inhalation, 2 free-breathing) on a 0.35T MR-linac were retrospectively evaluated. A hybrid MR/CT atlas and a deep learning three-dimensional (3D) U-Net propagated 13 substructures to TPCTs. Radiation oncologists revised contours using registered MRIs. Clinical treatment plans were re-optimized and evaluated for beam arrangement modifications to reduce substructure doses. Dosimetric assessment included mean and maximum (0.03cc) dose, left ventricular volume receiving 5Gy (LV-V5), and other clinical endpoints. As metrics of plan complexity, total MU and treatment time were evaluated between approaches.

RESULTS

Cardiac sparing plans reduced the mean heart dose (mean reduction 0.7 ± 0.6, range 0.1 to 2.5 Gy). Re-optimized plans reduced left anterior descending artery (LADA) mean and LADA_0.03cc (0.0-63.9% and 0.0 to 17.3 Gy, respectively). LV_0.03cc was reduced by >1.5 Gy for 10 patients while 6 cases had large reductions (>7%) in LV-V5. Left atrial mean dose was equivalent/reduced in all sparing plans (mean reduction 0.9 ± 1.2 Gy). The left main coronary artery was better spared in all cases for mean dose and D_0.03cc . One patient exhibited >10 Gy reduction in D_0.03cc to four substructures. There was no statistical difference in treatment time and MU, or clinical endpoints to the planning target volume, lung, esophagus, or spinal cord after re-optimization. Four patients benefited from new beam arrangements, leading to further dose reductions.

CONCLUSIONS

By introducing 0.35T MRIs acquired on an MR-linac to verify cardiac substructure segmentations for CT-based treatment planning, an opportunity was presented for more effective sparing with limited increase in plan complexity. Validation in a larger cohort with appropriate margins offers potential to reduce radiation-related cardiotoxicities.

Air Pollution across the Cancer Continuum: Extending Our Understanding of the Relationship between Environmental Exposures and Cancer

Previous studies of the environment and cancer have focused on etiology, showing that extrinsic factors in the environment contribute to 70% to 90% of cancers. Cancer patients and survivors often continue to live in the same neighborhoods they resided in before their cancer diagnosis. Thus, patients and survivors are exposed to the same environmental contexts that likely contributed to their original cancer, but little is known about the health effects of continued exposure to carcinogens after a cancer diagnosis. This commentary provides a summary of studies of the association between PM_2.5 and cancer mortality among patients and PM_2.5 and posttreatment morbidity among cancer survivors, and proposes new directions and opportunities for future research on such topics.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Myocardial deformation after radiotherapy: a layer-specific and territorial longitudinal strain analysis in a cohort of left-sided breast cancer patients (BACCARAT study)

Background

Radiotherapy for breast cancer (BC) and its resulting cardiac exposure are associated with subclinical left ventricular dysfunction characterized by early decrease of global longitudinal strain (LS) measurement based on 2D speckle-tracking echocardiography. Recent software allows multi-layer and segmental analysis of strain, which may be of interest to quantify and locate the impact of cardiac exposure on myocardial function and potentially increase the early detection of radiation-induced cardiotoxicity. The aim of the study was to evaluate whether decrease in LS 6 months after radiotherapy is layer-specific and if it varies according to the left ventricular regional level and the coronary arterial territories.

Methods

LS was measured at baseline before radiotherapy and 6 months post-radiotherapy. The LS was obtained for each myocardial layer (endocardial, mid-myocardial, epicardial), left ventricular regional level (basal, mid, apical) and coronary artery territory (left anterior descending artery (LAD), circumflex artery, right coronary artery).

Results

The study included 64 left-sided BC patients. Mean age was 58 years, mean doses to the heart, the left ventricle and the LAD were respectively 3.0, 6.7 and 16.4 Gy. The absolute decrease of LS was significant for the three layers (endocardial: − 20.0 ± 3.2% to − 18.8 ± 3.8%; mid-myocardial: − 16.0 ± 2.7% to − 15.0 ± 3.1%; epicardial: − 12.3 ± 2.5% to − 11.4 ± 2.8%, all p = 0.02), but only the relative decrease of LS in the endocardial layer was close to be significant (− 4.7%, p = 0.05). More precisely, the LS of the endocardial layer was significantly decreased for the most exposed parts of the left ventricle corresponding to the apical level (− 26.3 ± 6.0% vs. -24.2 ± 7.1%, p = 0.03) and LAD territory (− 22.8 ± 4.0% vs. -21.4 ± 4.8%, p = 0.03).

Conclusion

Six months post-radiotherapy, LS decreased predominantly in the endocardial layer of the most exposed part of the left ventricle. For precise evaluation of radiotherapy-induced cardiotoxicity and early left ventricular dysfunction, the endocardial layer-based LS might be the most sensitive parameter.

Trial registration

ClinicalTrials.gov: NCT02605512, Registered 6 November 2015 - Retrospectively registered.

Selection of patients with left breast cancer for IMRT with deep inspiration breath-hold technique

The deep inspiration breath-hold (DIBH) technique has been utilized to reduce the cardiac dose in left-sided breast cancer (BC) patients undergoing radiotherapy. Further investigation of the parameters for selecting which patients will benefit most from DIBH is essential. We performed dosimetric comparisons for 21 patients with left-sided BC who had both computed tomography (CT)-based free-breathing (FB) and DIBH plans. The doses to the heart and left anterior descending artery (LAD) and any reduction due to the DIBH technique were analysed. Based on CTFB plans, dosimetric analysis revealed that the irradiation doses to the heart and LAD were significantly correlated with the target volume, the ipsilateral lung volume (ILV) and the total lung volume (TLV). When patients had an ILV ≥ 950 cm3 or a TLV ≥ 2200 cm3, the irradiation doses to the heart and LAD were significantly decreased. Furthermore, the reduction in the mean heart dose (MHD) was correlated to the difference in lung volume between FB and DIBH. The difference in ILV between DIBH and FB of 1.8 indicated that the patients obtained more benefit from the DIBH technique. The data suggest that lung volume (ILV and TLV) measured on a CT-simulation scan and the difference between FB and DIBH could be utilized to help select patients for DIBH.

Advances in Preclinical Research Models of Radiation-Induced Cardiac Toxicity

Radiation therapy (RT) is an important component of cancer therapy, with >50% of cancer patients receiving RT. As the number of cancer survivors increases, the short- and long-term side effects of cancer therapy are of growing concern. Side effects of RT for thoracic tumors, notably cardiac and pulmonary toxicities, can cause morbidity and mortality in long-term cancer survivors. An understanding of the biological pathways and mechanisms involved in normal tissue toxicity from RT will improve future cancer treatments by reducing the risk of long-term side effects. Many of these mechanistic studies are performed in animal models of radiation exposure. In this area of research, the use of small animal image-guided RT with treatment planning systems that allow more accurate dose determination has the potential to revolutionize knowledge of clinically relevant tumor and normal tissue radiobiology. However, there are still a number of challenges to overcome to optimize such radiation delivery, including dose verification and calibration, determination of doses received by adjacent normal tissues that can affect outcomes, and motion management and identifying variation in doses due to animal heterogeneity. In addition, recent studies have begun to determine how animal strain and sex affect normal tissue radiation injuries. This review article discusses the known and potential benefits and caveats of newer technologies and methods used for small animal radiation delivery, as well as how the choice of animal models, including variables such as species, strain, and age, can alter the severity of cardiac radiation toxicities and impact their clinical relevance.

Protective effect of N-acetyl cysteine against radiotherapy-induced cardiac damage

Purpose: Although radiotherapy (RT) is an important component of cancer treatment, it induces adverse tissue reactions in the around of cancer tissue. Therefore, radioprotectives are needed to protect normal tissues. The aim of this study was to investigate the radioprotective effect of N-acetylcysteine (NAC) on RT-induced cardiac damage in rats for the acute term.Materials and methods: The animals were divided into four groups. The rats in control group were injected with saline for 7 d; the rats in NAC group were injected NAC at dose of 240 mg/kg d for 7 d; the rats in RT group were injected with saline for 7 d plus was irradiated 1 h after the last injection and the rats in NAC + RT group were injected with NAC for 7 d and irradiated 1 h after the last NAC dose. The electrocardiogram was recorded and evaluated PR interval, QRS duration, QT interval, T wave alterations and heart rate. Serum interleukin-4, interleukin-6, tumor necrosis factor-alpha, interleukin 1 beta, galectin-3 levels and creatine kinase and creatine kinase isoenzyme-MB activities were determined in all groups. Also, tissue malondialdehyde (MDA) and nitric oxide levels, superoxide dismutase, catalase and glutathione peroxidase activities were determined. In addition, histological changes of heart were evaluated. All measurements were performed 24 h after RT.Results: In the RT group, findings supporting cardiac injury were observed in the electrocardiogram. Also, cytokine levels and oxidative stress were significantly increased. Pretreatment of rats with NAC ameliorated cardiac injury induced by RT.Conclusions: Our findings suggested that NAC may be a potential radioprotector which is capable of preventing cardiac damage.

Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review

Purpose: Ionizing radiation is a risk factor to the whole organism, including the heart. Cardiac damage is considered to be a late effect of radiation exposure. While the acute cardiotoxicity of high doses is well characterized, the knowledge about nature and magnitude of the cardiac risk following lower doses exposure is incomplete. It has been shown that the cardiotoxic effects of radiation are source-, dose- and time-dependent. This paper provides an overview on these dependencies with regard to the molecular responses at the cellular and tissue levels. Main focus is put on the Nuclear Magnetic Resonance (NMR)-based and Mass Spectrometry (MS)-based metabolomic approaches in search of toxicity markers of relatively small doses of radiation.Conclusions: Available literature indicates that radiation exposure affects metabolites associated with: energy production, degradation of proteins and cell membranes, expression of proteins and stress response. Such effects are common for both animal and human studies. However, the specific metabolic response depends on several factors, including the examined organ. Radiation metabolomics can be used to explain the mechanisms of development of radiation-induced heart disease and to find an organ-specific biomarker of radiation exposure. The main aim of this review was to collect the information on the human cardiotoxicity biomarkers. In addition it also summarizes results of the studies on the metabolic responses to ionizing radiation for other organs, as well as the comparative data concerning animal studies.

Radiation effect on late cardiopulmonary toxicity: An analysis comparing supine DIBH versus prone techniques for breast treatment

Two commonly used whole breast irradiation (WBI) techniques, deep inspiration breath hold (DIBH) and prone positioning, are compared with regard to dosimetry and estimated late cardiac morbidity and secondary lung cancer mortality using published models. Forty patients with left-sided DCIS or breast cancer who underwent lumpectomy and required adjuvant WBI were enrolled on a prospective trial comparing supine DIBH (S-DIBH) with prone free breathing (P-FB) planning. Patients underwent CT simulation in both positions; two plans were generated for each patient. Comparative dosimetry was available for 34 patients. Mean cardiac and lung doses were calculated. Risk of death from ischemic heart disease (IHD), risk of at least one acute coronary event (ACE), and lung cancer mortality were estimated from published data. Difference between S-DIBH and P-FB plans was compared using paired two-tailed t test. Estimated mean risk of death from IHD by age 80 was 0.1% (range 0.0%-0.2%) for both plans (P = 1.0). Mean risk of at least one ACE was 0.3% (range 0.1%-0.6%) for both plans (P = .6). Mean lung cancer mortality risk was 1.4% (range 0.5%-15.4%) for S-DIBH and 1.0% (range 0.4%-9.8%) for P-FB (P = .008). Excess lung cancer mortality due to radiation was 0.5% (range 0.1%-6.0%) with S-DIBH and 0.0% (range 0.0%-0.4%) with P-FB (P = .008). Both S-DIBH and P-FB provide excellent cardiac sparing. Prone positioning results in lower lung dose than S-DIBH and leads to an absolute decrease of 0.5% in excess lung cancer mortality for patients receiving WBI.

Radiobiological models in prediction of radiation cardiotoxicity

Coronary disease induced by previous radiotherapy is the most common cause of death among patients treated with radiotherapy for cancer. Risk factors that may affect the frequency and intensity of radiotherapy's cardiac toxicity are primarily the radiation dose and the volume of the heart exposed to radiation. The prolonged survival time of patients after radiotherapy, but also the intensive development of modern radiotherapy techniques results in the necessity of precise estimation of both tumor control probability, and the risk of normal tissue damage, thus the models describing the probability of complications in normal tissues have also been developed. The response from the cardiovascular system to high-dose radiation is known and associated with a pro-inflammatory response. However, the effect of low doses may be completely different because it induces an anti-inflammatory response. Also, there is no unambiguous answer to the question of whether RICD is a deterministic effect. Moreover, there is a lack of literature data on the use of known radiobiological models to assess the risk of cardiovascular complications. The models described are general and concerns any healthy tissue. Therefore, when planning treatment for patients, particular attention should be paid to the dose and area of ​​the heart to be irradiated.

Early detection of subclinical left ventricular dysfunction after breast cancer radiation therapy using speckle-tracking echocardiography: association between cardiac exposure and longitudinal strain reduction (BACCARAT study)

BACKGROUND

Breast cancer (BC) radiotherapy (RT) can induce cardiotoxicity, with adverse events often observed many years after BC RT. Subclinical left ventricular (LV) dysfunction can be detected early after BC RT with global longitudinal strain (GLS) measurement based on 2D speckle-tracking echocardiography. This 6-month follow-up analysis from the BACCARAT prospective study aimed to investigate the association between cardiac radiation doses and subclinical LV dysfunction based on GLS reduction.

METHODS

The patient study group consisted of 79 BC patients (64 left-sided BC, 15 right-sided BC) treated with RT without chemotherapy. Echocardiographic parameters, including GLS, were measured before RT and 6 months post-RT. The association between subclinical LV dysfunction, defined as GLS reduction > 10%, and radiation doses to whole heart and the LV were performed based on logistic regressions. Non-radiation factors associated with subclinical LV dysfunction including age, BMI, hypertension, hypercholesterolemia and endocrine therapy were considered for multivariate analyses.

RESULTS

A mean decrease of 6% in GLS was observed (- 15.1% ± 3.2% at 6 months vs. - 16.1% ± 2.7% before RT, p = 0.01). For left-sided patients, mean heart and LV doses were 3.1 ± 1.3 Gy and 6.7 ± 3.4 Gy respectively. For right-sided patients, mean heart dose was 0.7 ± 0.5 Gy and median LV dose was 0.1 Gy. Associations between GLS reduction > 10% (37 patients) and mean doses to the heart and the LV as well as the V20 were observed in univariate analysis (Odds Ratio = 1.37[1.01-1.86], p = 0.04 for Dmean Heart; OR = 1.14 [1.01-1.28], p = 0.03 for Dmean LV; OR = 1.08 [1.01-1.14], p = 0.02 for LV V20). In multivariate analysis, these associations did not remain significant after adjustment for non-radiation factors. Further exploratory analysis allowed identifying a subgroup of patients (LV V20 > 15%) for whom a significant association with subclinical LV dysfunction was found (adjusted OR = 3.97 [1.01-15.70], p = 0.048).

CONCLUSIONS

This analysis indicated that subclinical LV dysfunction defined as a GLS decrease > 10% is associated with cardiac doses, but adjustment for non-radiation factors such as endocrine therapy lead to no longer statistically significant relationships. However, LV dosimetry may be promising to identify high-risk subpopulations. Larger and longer follow-up studies are required to further investigate these associations.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02605512, Registered 6 November 2015 - Retrospectively registered.

Assessment of Early Radiation-Induced Changes in Left Ventricular Function by Myocardial Strain Imaging After Breast Radiation Therapy

BACKGROUND

Radiation therapy (RT)-induced cardiotoxicity is among the concerning sequelae of breast cancer (BCA) treatment, particularly in HER2-positive BCA patients who receive anthracyclines and trastuzumab-based therapy. The aim of this study was to assess for early RT-induced changes in echocardiographic and circulating biomarkers of left ventricular (LV) function and evaluate their association with radiation dose to the heart among patients with HER2-positive BCA treated with contemporary RT.

METHODS

A total of 47 women with HER2-positive BCA who were treated with an anthracycline, trastuzumab, and RT to the breast and/or chest wall ± regional lymph nodes were included in this study. Two-dimensional echocardiography with speckle-tracking imaging was performed at baseline (prechemotherapy), prior to and after RT (pre-RT and post-RT), and 6 months post-RT. High-sensitivity troponin I (hsTnI) was measured pre-RT and post-RT. Associations between mean heart dose (MHD) and changes in LV function after RT were examined in multivariable linear regression models.

RESULTS

The MHD was 1.8 ± 1.5 Gy for patients receiving left-sided RT (n = 26) and 1.1 ± 1.3 Gy for patients receiving right-sided RT (n = 21). Pre-RT, post-RT, and 6-month post-RT echocardiograms were performed at median (interquartile range) of 49 days (27, 77) before and 54 days (25, 78) and 195 days (175, 226) after RT, respectively. Compared with pre-RT, a minimal decrease in LV ejection fraction was observed post-RT (61% ± 7% vs 59% ± 8%; P = .003) without any significant change in global longitudinal, circumferential, or radial strain or diastolic indices at the post-RT timepoint. Median (interquartile range) concentrations of hsTnI decreased from 5.7 pg/mL (3.0, 8.7) pre-RT to 3.7 pg/mL (2.0, 5.9) post-RT. There was no significant change in systolic or diastolic indices of LV function at 6 months post-RT compared with pre-RT. MHD was not associated with changes in echocardiographic parameters of LV function after RT.

CONCLUSIONS

Breast RT using contemporary techniques can be delivered without evidence of early subclinical LV dysfunction or injury as measured by echocardiography and hsTnI in patients treated with anthracyclines and trastuzumab. Future studies should focus on identifying alternative biomarkers to elucidate early RT-induced cardiovascular effects and further characterizing long-term cardiovascular outcomes associated with contemporary breast RT.

Is mean heart dose a relevant surrogate parameter of left ventricle and coronary arteries exposure during breast cancer radiotherapy: a dosimetric evaluation based on individually-determined radiation dose (BACCARAT study)

Background

Intra-individual heterogeneity of cardiac exposure is an issue in breast cancer (BC) radiotherapy that was poorly considered in previous cardiotoxicity studies mainly based on mean heart dose (MHD). This dosimetric study analyzes the distribution of individually-determined radiation doses to the heart and its substructures including coronary arteries and evaluate whether MHD is a relevant surrogate parameter of dose for these substructures.

Methods

Data were collected from the BACCARAT prospective study that included left or right unilateral BC patients treated with 3D-Conformal Radiotherapy (RT) between 2015 and 2017 and followed-up for 2 years with repeated cardiac imaging examinations. A coronary computed tomography angiography (CCTA) was performed before RT for all patients. Registration of the planning CT and CCTA images allowed delineation of the coronary arteries on the planning CT images. Using the 3D dose matrix generated during treatment planning and the added coronary contours, dose distributions were generated for whole heart and the following substructures: left ventricle (LV), left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCX) and right coronary artery (RCA). A descriptive analysis of the physical doses in Gray (Gy) was performed, Dmean was the volume-weighted mean dose.

Results

Dose distributions were generated for 89 left-sided BC patients (MHD = 2.9 ± 1.5 Gy, Dmean_LAD = 15.7 ± 3.1 Gy) and 15 right-sided BC patients (MHD = 0.5 ± 0.1 Gy; Dmean_RCA = 1.2 ± 0.4 Gy). For left-sided BC patients, the ratio Dmean_LAD/MHD was around 5. Pearson correlation coefficients between MHD and Dmean for delineated substructures were all statistically significant. However, for all substructures, the coefficient of determination R² indicated that the proportion of the variance in Dmean of the substructure predictable from MHD was moderate to low (in particular R² = 0.45 for LAD). Among left-sided BC patients with MHD < 3Gy, 56% of patients could nevertheless receive LAD doses above 40Gy (V40 > 0).

Conclusion

Our study illustrates that MHD is not enough to predict with confidence individual patient dose to the LV and coronary arteries, in particular the LAD. For precise radiotherapy-induced cardiotoxicity studies it would be necessary to consider the distribution of doses within these cardiac substructures rather than just the MHD.

Trial registration

ClinicalTrials.gov: NCT02605512, Registered 6 November 2015 - Retrospectively registered.

Cardiac Substructure Segmentation and Dosimetry Using a Novel Hybrid Magnetic Resonance and Computed Tomography Cardiac Atlas

PURPOSE

Radiation dose to the heart and cardiac substructures has been linked to cardiotoxicities. Because cardiac substructures are poorly visualized on treatment-planning computed tomography (CT) scans, we used the superior soft-tissue contrast of magnetic resonance (MR) imaging to optimize a hybrid MR/CT atlas for substructure dose assessment using CT.

METHODS AND MATERIALS

Thirty-one patients with left-sided breast cancer underwent a T2-weighted MR imaging scan and noncontrast simulation CT scans. A radiation oncologist delineated 13 substructures (chambers, great vessels, coronary arteries, etc) using MR/CT information via cardiac-confined rigid registration. Ground-truth contours for 20 patients were inputted into an intensity-based deformable registration atlas and applied to 11 validation patients. Automatic segmentations involved using majority vote and Simultaneous Truth and Performance Level Estimation (STAPLE) strategies with 1 to 15 atlas matches. Performance was evaluated via Dice similarity coefficient (DSC), mean distance to agreement, and centroid displacement. Three physicians evaluated segmentation performance via consensus scoring by using a 5-point scale. Dosimetric assessment included measurements of mean heart dose, left ventricular volume receiving 5 Gy, and left anterior descending artery mean and maximum doses.

RESULTS

Atlas approaches performed similarly well, with 7 of 13 substructures (heart, chambers, ascending aorta, and pulmonary artery) having DSC >0.75 when averaged over 11 validation patients. Coronary artery segmentations were not successful with the atlas-based approach (mean DSC <0.3). The STAPLE method with 10 matches yielded the highest DSC and the lowest mean distance to agreement for all high-performing substructures (omitting coronary arteries). For the STAPLE method with 10 matches, >50% of all validation contours had centroid displacements <3.0 mm, with the largest shifts in the coronary arteries. Atlas-generated contours had no statistical difference from ground truth for left anterior descending artery maximum dose, mean heart dose, and left ventricular volume receiving 5 Gy (P > .05). Qualitative contour grading showed that 8 substructures required minor modifications.

CONCLUSIONS

The hybrid MR/CT atlas provided reliable segmentations of chambers, heart, and great vessels for patients undergoing noncontrast CT, suggesting potential widespread applicability for routine treatment planning.

Assessment of a guideline-based heart substructures delineation in left-sided breast cancer patients undergoing adjuvant radiotherapy : Quality assessment within a randomized phase III trial testing a cardioprotective treatment strategy (SAFE-2014)

BACKGROUND AND PURPOSE

In our institute, breast cancer patients undergoing adjuvant treatment are included in a protocol aimed to reduce cardiovascular morbidity (SAFE-2014, NCT2236806), assessing preclinical heart damage with heart speckle-tracking ultrasound. To develop a dose constraint related to subclinical heart damage, a reliable delineation of heart substructures based on a pre-existing guideline was made.

PATIENTS AND METHODS

Heart substructures of 16 left-sided breast cancer patients included in the SAFE protocol were delineated by five operators. For each substructure, a multi-contour delineation based on a majority vote algorithm (MCD) was created. A consensus-based delineation (CBD) was developed by an independent team of two blinded operators. Dice similarity coefficients (DSC) between volumes delineated by different operators and the MCD were collected and reported, as well as DSC between CBD and MCD.

RESULTS

Mean DSCs between heart chambers delineated by each operator and the corresponding MCDs ranged between 0.78 and 0.96. Mean DSC between substructures delineated by all single operators and the corresponding MCD ranged between 0.84 and 0.94. Mean DSC between CBD and the corresponding MCD ranged from 0.89 to 0.97.

CONCLUSION

Results showed low inter-observer variability of heart substructure delineation. This constitutes an external validation of the contouring atlas used, allowing a reliable dosimetric assessment of these volumes within the SAFE-2014 trial.

Early Detection of Cardiovascular Changes After Radiotherapy for Breast Cancer: Protocol for a European Multicenter Prospective Cohort Study (MEDIRAD EARLY HEART Study)

Background

Breast cancer is the most common cancer among women, and radiotherapy plays a major role in its treatment. However, breast cancer radiotherapy can lead to incidental irradiation of the heart, resulting in an increased risk for a variety of heart diseases arising many years after radiotherapy. Therefore, identifying breast cancer patients at the highest risk for radiation-induced cardiac complications is crucial for developing strategies for primary and secondary prevention, which may contribute to healthy aging. There is still a need for precise knowledge on the relationship between radiation dose to specific cardiac structures and early subclinical cardiac changes and their occurrence over time that could finally lead to cardiac complications.

Objective

The MEDIRAD EARLY HEART study aims to identify and validate new cardiac imaging and circulating biomarkers of radiation-induced cardiovascular changes arising within first 2 years of breast cancer radiotherapy and to develop risk models integrating these biomarkers combined with precise dose metrics of cardiac structures based on three-dimensional dosimetry.

Methods

The EARLY HEART study is a multicenter, prospective cohort study in which 250 women treated for breast cancer and followed for 2 years after radiotherapy will be included. Women treated with radiotherapy without chemotherapy for a unilateral breast cancer and aged 40-75 years meet the inclusion criteria. Baseline and follow-up data include cardiac measurements based on two-dimensional speckle-tracking echocardiography, computed tomography coronary angiography, cardiac magnetic resonance imaging, and a wide panel of circulating biomarkers of cardiac injury. The absorbed dose will be evaluated globally for the heart and different substructures. Furthermore, the dose-response relationship will allow modeling the radiation-induced occurrence and evolution of subclinical cardiac lesions and biomarkers to develop prediction models.

Results

This study details the protocol of the MEDIRAD EARLY HEART study and presents the main limits and advantages of this international project. The inclusion of patients began in 2017. Preliminary results are expected to be published in 2019, and complete analysis should be published in 2021.

Conclusions

The MEDIRAD EARLY HEART study will allow identifying the main cardiac imaging and blood-based determinants of radiation-induced cardiac injuries to better propose primary and secondary preventive measures in order to contribute to enhanced patient care and quality of life.

Trial Registration

ClinicalTrials.gov NCT03297346; https://clinicaltrials.gov/ct2/show/NCT03297346 (Archived by WebCite at http://www.webcitation.org/72KS7MIUU)

Registered Report Identifier

RR1-10.2196/9906

Radiation Matters of the Heart: A Mini Review

Radiation Therapy (RT) has been critical in cancer treatment regimens to date. However, it has been shown that ionizing radiation is also associated with increased risk of damage to healthy tissues. At high radiation doses, varied effects including inactivation of cells in treated tissue and associated functional impairment are seen. These range from direct damage to the heart; particularly, diffuse fibrosis of the pericardium and myocardium, adhesion of the pericardium, injury to the blood vessels and stenosis. Cardiac damage is mostly a late responding end-point, occurring anywhere between 1 and 10 years after radiation procedures. Cardiovascular disease following radiotherapy was more common with radiation treatments used before the late 1980s. Modern RT regimens with more focused radiation beams, allow tumors to be targeted more precisely and shield the heart and other healthy tissues for minimizing the radiation damage to normal cells. In this review, we discuss radiation therapeutic doses used and post-radiation damage to the heart muscle from published studies. We also emphasize the need for early detection of cardiotoxicity and the need for more cardio-protection approaches where feasible.

Proton therapy for locally advanced breast cancer: A systematic review of the literature

BACKGROUND

Radiation therapy plays a major role in the management of adjuvant breast cancer with nodal involvement, with an iatrogenic increase of cardio-vascular risk. Photon therapy, even with intensity modulation, has the downsides of high mean heart dose and heterogeneous target coverage, particularly in the case of internal mammary irradiation. This systematic review of the literature aims to evaluate proton therapy in locally advanced breast cancer.

MATERIAL AND METHODS

PubMed was searched for original full-text articles with the following search terms: «Proton Therapy» and «Breast Cancer». On-going trials were collected using the words "Breast Cancer" and "Protons".

RESULTS

13 articles met the criteria: 6 with passive proton therapy (Double Scattering), 5 with Pencil Beam Scanning (PBS) and 2 with a combination of both. Proton therapy offered a better target coverage than photons, even compared with intensity modulation radiation therapy (including static or rotational IMRT or tomotherapy). With proton therapy, volumes receiving 95% of the dose were around 98%, with low volumes receiving 105% of the dose. Proton therapy often decreased mean heart dose by a factor of 2 or 3, i.e. 1 Gy with proton therapy versus 3 Gy with conventional 3D, and 6 Gy for IMRT. Lungs were better spared with proton therapy than with photon therapy. Cutaneous toxicity observed with double scattering is improved with PBS.

CONCLUSION

Proton therapy reduces mean heart dose in breast cancer irradiation, probably reducing late cardio-vascular toxicity. Large clinical studies will likely confirm a clinical benefit of proton therapy.

Left-sided breast cancer and risks of secondary lung cancer and ischemic heart disease : Effects of modern radiotherapy techniques

PURPOSE

Modern breast cancer radiotherapy techniques, such as respiratory-gated radiotherapy in deep-inspiration breath-hold (DIBH) or volumetric-modulated arc radiotherapy (VMAT) have been shown to reduce the high dose exposure of the heart in left-sided breast cancer. The aim of the present study was to comparatively estimate the excess relative and absolute risks of radiation-induced secondary lung cancer and ischemic heart disease for different modern radiotherapy techniques.

METHODS

Four different treatment plans were generated for ten computed tomography data sets of patients with left-sided breast cancer, using either three-dimensional conformal radiotherapy (3D-CRT) or VMAT, in free-breathing (FB) or DIBH. Dose-volume histograms were used for organ equivalent dose (OED) calculations using linear, linear-exponential, and plateau models for the lung. A linear model was applied to estimate the long-term risk of ischemic heart disease as motivated by epidemiologic data. Excess relative risk (ERR) and 10-year excess absolute risk (EAR) for radiation-induced secondary lung cancer and ischemic heart disease were estimated for different representative baseline risks.

RESULTS

The DIBH maneuver resulted in a significant reduction of the ERR and estimated 10-year excess absolute risk for major coronary events compared to FB in 3D-CRT plans (p = 0.04). In VMAT plans, the mean predicted risk reduction through DIBH was less pronounced and not statistically significant (p = 0.44). The risk of radiation-induced secondary lung cancer was mainly influenced by the radiotherapy technique, with no beneficial effect through DIBH. VMAT plans correlated with an increase in 10-year EAR for radiation-induced lung cancer as compared to 3D-CRT plans (DIBH p = 0.007; FB p = 0.005, respectively). However, the EARs were affected more strongly by nonradiation-associated risk factors, such as smoking, as compared to the choice of treatment technique.

CONCLUSION

The results indicate that 3D-CRT plans in DIBH pose the lowest risk for both major coronary events and secondary lung cancer.

Validation and Modification of a Prediction Model for Acute Cardiac Events in Patients With Breast Cancer Treated With Radiotherapy Based on Three-Dimensional Dose Distributions to Cardiac Substructures

Purpose

A relationship between mean heart dose (MHD) and acute coronary event (ACE) rate was reported in a study of patients with breast cancer (BC). The main objective of our cohort study was to validate this relationship and investigate if other dose-distribution parameters are better predictors for ACEs than MHD.

Patients and Methods

The cohort consisted of 910 consecutive female patients with BC treated with radiotherapy (RT) after breast-conserving surgery. The primary end point was cumulative incidence of ACEs within 9 years of follow-up. Both MHD and various dose-distribution parameters of the cardiac substructures were collected from three-dimensional computed tomography planning data.

Results

The median MHD was 2.37 Gy (range, 0.51 to 15.25 Gy). The median follow-up time was 7.6 years (range, 0.1 to 10.1 years), during which 30 patients experienced an ACE. The cumulative incidence of ACE increased by 16.5% per Gy (95% CI, 0.6 to 35.0; P = .042). Analysis showed that the volume of the left ventricle receiving 5 Gy (LV-V5) was the most important prognostic dose-volume parameter. The most optimal multivariable normal tissue complication probability model for ACEs consisted of LV-V5, age, and weighted ACE risk score per patient (c-statistic, 0.83; 95% CI, 0.75 to 0.91).

Conclusion

A significant dose-effect relationship was found for ACEs within 9 years after RT. Using MHD, the relative increase per Gy was similar to that reported in the previous study. In addition, LV-V5 seemed to be a better predictor for ACEs than MHD. This study confirms the importance of reducing exposure of the heart to radiation to avoid excess risk of ACEs after radiotherapy for BC.