Radiation and the heart: systematic review of dosimetry and cardiac endpoints

Cardiac substructure delineation in radiation therapy - A state-of-the-art review

Delineation of cardiac substructures is crucial for a better understanding of radiation-related cardiotoxicities and to facilitate accurate and precise cardiac dose calculation for developing and applying risk models. This review examines recent advancements in cardiac substructure delineation in the radiation therapy (RT) context, aiming to provide a comprehensive overview of the current level of knowledge, challenges and future directions in this evolving field. Imaging used for RT planning presents challenges in reliably visualising cardiac anatomy. Although cardiac atlases and contouring guidelines aid in standardisation and reduction of variability, significant uncertainties remain in defining cardiac anatomy. Coupled with the inherent complexity of the heart, this necessitates auto-contouring for consistent large-scale data analysis and improved efficiency in prospective applications. Auto-contouring models, developed primarily for breast and lung cancer RT, have demonstrated performance comparable to manual contouring, marking a significant milestone in the evolution of cardiac delineation practices. Nevertheless, several key concerns require further investigation. There is an unmet need for expanding cardiac auto-contouring models to encompass a broader range of cancer sites. A shift in focus is needed from ensuring accuracy to enhancing the robustness and accessibility of auto-contouring models. Addressing these challenges is paramount for the integration of cardiac substructure delineation and associated risk models into routine clinical practice, thereby improving the safety of RT for future cancer patients.

Organ-sparing techniques and dose-volume constrains used in breast cancer radiation therapy - Results from European and Latin American surveys

Background

Advances in local and systemic therapies have improved the outcomes of patients with breast cancer (BC), leading to a possible increased risk for postoperative radiation therapy (RT) late adverse events. The most adequate technologies and dose constraints for organs at risk (OAR) in BC RT have yet to be defined.

Methods

An online survey was distributed to radiation oncologists (ROs) practicing in Europe and Latin America including the Caribbean (LAC) through personal contacts, RO and BC professional groups' networks. Demographic data and clinical practice information were collected.

Results

 The study included 585 responses from ROs practicing in 57 different countries. The most frequently contoured OAR by European and LAC participants were the whole heart (96.6 % and 97.7 %), the ipsilateral (84.3 % and 90.8 %), and contralateral lung (71.3 % and 77.4 %), whole lung (69.8 % and 72.9 %), and the contralateral breast (66.4 % and. 83.2 %). ESTRO guidelines were preferred in Europe (33.3 %) and the RTOG contouring guideline was the most popular in LAC (62.2 %), while some participants used both recommendations (13.2 % and 19.2 %). IMRT (68.6 % and 59.1 %) and VMAT (65.6 % and 60.2 %) were the preferred modalities used in heart sparing strategies, followed by deep inspiration breath-hold (DIBH) (54.8 % and 37.4 %) and partial breast irradiation (PBI) (41.6 % and 24.6 %). Only a small percentage of all ROs reported the dose-volume constraints for OAR used in routine clinical practice. A mean heart dose (Heart-Dmean) between 4 and 5 Gy was the most frequently reported parameter (17.2 % and 39.3 %).

Conclusion

 The delineation approaches and sparing techniques for OAR in BC RT vary between ROs worldwide. The low response rate to the dose constraints subset of queries reflects the uncertainty surrounding this topic and supports the need for detailed consensus recommendations in the clinical practice.

Comparative assessment of radiation therapy-induced vasculitis using [18F]FDG-PET/CT in patients with non-small cell lung cancer treated with proton versus photon radiotherapy

PURPOSE

To assess radiation therapy (RT)-induced vasculitis in patients with non-small cell lung cancer (NSCLC) by examining changes in the uptake of 18F-fluoro-D-deoxyglucose ([18F]FDG) by positron emission tomography/computed tomography (PET/CT) images of the ascending aorta (AA), descending aorta (DA), and aortic arch (AoA) before and after proton and photon RT.

METHOD

Thirty-five consecutive locally advanced NSCLC patients were definitively treated with proton (n = 27) or photon (n = 8) RT and concurrent chemotherapy. The patients were prospectively enrolled to undergo [18F]FDG-PET/CT imaging before and 3 months after RT. An adaptive contrast-oriented thresholding algorithm was applied to generate mean standardized uptake values (SUVmean) for regions of interest (ROIs) 3 mm outside and 3 mm inside the outer perimeter of the AA, DA, and AoA. These ROIs were employed to exclusively select the aortic wall and remove the influence of blood pool activity. SUVmeans before and after RT were compared using two-tailed paired t-tests.

RESULTS

RT treatments were associated with increased SUVmeans in the AA, DA, and AoA-1.9%, 0.3%, and 1.3% for proton and 15.8%, 9.5%, and 15.5% for photon, respectively. There was a statistically significant difference in the ∆SUVmean (post-RT SUVmean - pre-RT SUVmean) in patients treated with photon RT when compared to ∆SUVmean in patients treated with proton RT in the AA (p = 0.043) and AoA (p = 0.015). There was an average increase in SUVmean that was related to dose for photon patients (across structures), but that was not seen for proton patients, although the increase was not statistically significant.

CONCLUSION

Our results suggest that patients treated with photon RT for NSCLC may exhibit significantly more RT-induced inflammation (measured as ∆SUVmean) in the AA and AoA when compared to patients who received proton RT. Knowledge gained from further analyses in larger cohorts could aid in treatment planning and help prevent the significant morbidity and mortality associated with RT-induced vascular complications.

TRIAL REGISTRATION

NCT02135679.

Cardiac Arrhythmias in Patients Treated for Lung Cancer: A Review

Cardio-oncology currently faces one of the greatest challenges in the field of health care. The main goal of this discipline is to ensure that patients treated for cancer do not suffer or die from cardiovascular disease. The number of studies on the mechanisms of heart injury during cancer treatment is constantly increasing. However, there is insufficient data on heart rhythm disorders that may result from this treatment. This issue seems to be particularly important in patients with lung cancer, in whom anticancer therapy, especially radiotherapy, may contribute to the onset of cardiac arrhythmias. The observed relationship between cardiac dosimetry and radiotherapy-induced cardiotoxicity in lung cancer treatment may explain the increased mortality from cardiovascular causes in patients after chest irradiation. Further research is essential to elucidate the role of cardiac arrhythmias in this context. Conversely, recent reports have highlighted the application of stereotactic arrhythmia radioablation (STAR) in the treatment of ventricular tachycardia. This review of available studies on the epidemiology, pathogenesis, diagnosis, and treatment of arrhythmias in patients treated for lung cancer aims to draw attention to the need for regular cardiological monitoring in this group of patients. Improving cardiac care for patients with lung cancer has the potential to enhance their overall therapeutic outcomes.

Summary of Cardiac Computed Tomographic Imaging in Cardio-Oncology: An Expert Consensus Document of the Society of Cardiovascular Computed Tomography

PURPOSE

The purpose of this document is to develop a summary of recommendations from the "Cardiac Computed Tomographic Imaging in Cardio-Oncology: An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT)" document and provide commentary on key recommendations that are relevant to radiation oncology.

METHODS

In July 2019, the SCCT convened a multidisciplinary panel of experts to develop a consensus document based on a literature search and a formal consensus process, which was separately published in 2022. A new panel consisting of the radiation oncologist from the original guideline and additional radiation oncologists was formed to address SCCT recommendations and their implications for radiation oncology.

SUMMARY

The SCCT consensus document included 6 core sections. Two of these sections were identified as particularly relevant to radiation oncologists. These include evaluation of shared risk factors and role of cardiac computed tomography in risk stratification of patients with cancer (section 1) and the role of cardiac computed tomography in the evaluation of the effects of radiation therapy (section 4). These recommendations are summarized, with additional commentary on the role of radiation oncologists as individual practitioners and radiation oncology practices as a whole in evaluation of coronary artery calcifications on computed tomography images; assessment of the effects of radiation therapy on cardiovascular risk after treatment; and management of patients at elevated risk of cardiovascular sequelae of treatment. Radiation oncologists should be aware of the recommendations in the SCCT consensus document and consider those elements that relate to their practice. This summary document calls attention to the key roles and limitations of radiation oncologists and radiation oncology practices in managing cardiotoxicity risk and highlights the need for ongoing study on the effects of radiation therapy on the heart, cardiac substructures, and long-term risk of cardiotoxicity related to treatment.

A pooled analysis of nine studies in one institution to assess effects of whole heart irradiation in rat models

PURPOSE

Over the years, animal models of local heart irradiation have provided insight into mechanisms of and treatments for radiation-induced heart disease in human populations. However, it is not completely clear which manifestations of radiation injury are most commonly seen after whole heart irradiation, and whether certain biological factors impact experimental results. Combining 9 homogeneous studies in rat models of whole heart irradiation from one laboratory, we sought to identify experimental and/or biological factors that impact heart outcomes. We evaluated the usefulness of including (1) heart rate and (2) bodyweight as covariates when analyzing biological parameters, and (3) we determined which echocardiography, histological, and immunohistochemistry parameters are most susceptible to radiation effects. Finally, (4) as an educational example, we illustrate a hypothetical sample size calculation for a study design commonly used in evaluating radiation modifiers, using the pooled estimates from the 9 rat studies only for context. The results may assist investigators in the design and analyses of pre-clinical studies of whole heart irradiation.

MATERIALS AND METHODS

We made use of data from 9 rat studies from our labs, 8 published elsewhere in 2008-2017, and one unpublished study. Echocardiography, histological, and immunohistochemical parameters were collected from these studies. Using mixed effects analysis of covariance models, we estimated slopes for heart rate and bodyweight and estimated the radiation effect on each of the parameters.

RESULTS

Bodyweight was related to most echocardiography parameters, and heart rate had an effect on echocardiography parameters related to the diameter of the left ventricle. For some parameters, there was evidence that heart rate and bodyweight relationships with the parameter depended on whether the rats were irradiated. Radiation effects were found in systolic measures of echocardiography parameters related to the diameter of the left ventricle, with ejection fraction and fractional shortening, with atrial wall thickness, and with histological measures of capillary density, collagen deposition, and mast cells infiltration in the heart.

CONCLUSION

Accounting for bodyweight, as well as heart rate, in analyses of echocardiography parameters should reduce variability in estimated radiation effects. Several echocardiography and histological parameters were particularly susceptible to whole heart irradiation, showing robust effects compared to sham-irradiation. Lastly, we provide an example approach for a sample size calculation that will contribute to a rigorous study design and reproducibility in experiments studying radiation modifiers.

Cancer and Postradiotherapy Cardiotoxicity: How to Face Damage in Women’s Hearts?

Cancer and cardiovascular disease are the two main causes of death worldwide in both men and women. In the past decades, survival rate in cancer patients has substantially improved due to new treatments and developments in radiation therapy (RT). In women, breast cancer (BC) is the leading cause of cancer death and thoracic RT is a main component of the treatment in many cases. Nevertheless, despite new techniques that limit the area receiving RT, cardiac damage is still an important concern in BC patients. In this review, the following aspects will be addressed: pathophysiology of postradiotherapy heart damage in women with BC; mechanisms, diagnosis and prevention/management of heart damage; and future areas of potential research for radiotherapy injury in women.

Systematic review and updated recommendations for cardiomyopathy surveillance for survivors of childhood, adolescent, and young adult cancer from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Survivors of childhood, adolescent, and young adult cancer, previously treated with anthracycline chemotherapy (including mitoxantrone) or radiotherapy in which the heart was exposed, are at increased risk of cardiomyopathy. Symptomatic cardiomyopathy is typically preceded by a series of gradually progressive, asymptomatic changes in structure and function of the heart that can be ameliorated with treatment, prompting specialist organisations to endorse guidelines on cardiac surveillance in at-risk survivors of cancer. In 2015, the International Late Effects of Childhood Cancer Guideline Harmonization Group compiled these guidelines into a uniform set of recommendations applicable to a broad spectrum of clinical environments with varying resource availabilities. Since then, additional studies have provided insight into dose thresholds associated with a risk of asymptomatic and symptomatic cardiomyopathy, have characterised risk over time, and have established the cost-effectiveness of different surveillance strategies. This systematic Review and guideline provides updated recommendations based on the evidence published up to September, 2020.

Myocardial Contractility Pattern Characterization in Radiation-Induced Cardiotoxicity Using Magnetic Resonance Imaging: A Pilot Study with ContractiX

Radiation therapy (RT) plays an integral role in treating thoracic cancers, despite the risk of radiation-induced cardiotoxicity. We hypothesize that our newly developed magnetic resonance imaging (MRI)-based contractility index (ContractiX) is a sensitive marker for early detection of RT-induced cardiotoxicity in a preclinical rat model of thoracic cancer RT. Adult salt-sensitive rats received image-guided heart RT and were imaged with MRI at 8 weeks and 10 weeks post-RT or sham. The MRI exam included cine and tagging sequences to measure left-ventricular ejection fraction (LVEF), mass, myocardial strain, and ContractiX. Furthermore, ventricular torsion, diastolic strain rate, and mechanical dyssynchrony were measured. Statistical analyses were performed between the sham, 8 weeks post-RT, and 10 weeks post-RT MRI parameters. The results showed that both LVEF and myocardial mass increased post-RT. Peak systolic strain and ContractiX significantly decreased post-RT, with a more relative reduction in ContractiX compared to strain. ContractiX showed an inverse nonlinear relationship with LVEF and continuously decreased with time post-RT. While early diastolic strain rate and mechanical dyssynchrony significantly changed post-RT, ventricular torsion changes were not significant post-RT. In conclusion, ContractiX measured via non-contrast MRI is a sensitive early marker for the detection of subclinical cardiac dysfunction post-RT, and it is superior to other MRI cardiac measures.

Stereotactic Radiotherapy in the Management of Ventricular Tachycardias: More Questions than Answers?

Stereotactic body radiotherapy is a recent promising therapeutic alternative in cases of failed catheter ablation for recurrent ventricular tachycardias (VTs) in patients with structural heart disease. Initial clinical experience with a single radiation dose of 25 Gy shows reasonable efficacy in the reduction of VT recurrences with acceptable acute toxicity. Many unanswered questions remain, including unknown mechanism of action, variable time to effect, optimal method of substrate targeting, long-term safety, and definition of an optimal candidate for this treatment."

Mediastinal irradiation and valvular heart disease

Anticancer therapy has the potential to cause unwanted cardiovascular side effects. Utilization of radiation therapy to treat tumors near the heart can result in radiation-induced valvular heart disease among other cardiovascular pathologies. The aim of this review is to describe the epidemiology, pathophysiology, risk prediction, non-invasive imaging modalities and management of radiation-induced valvular heart disease with a focus on pre-operative risk assessment and contemporary treatment options.

Murine models of radiation cardiotoxicity: A systematic review and recommendations for future studies

BACKGROUND AND PURPOSE

The effects of radiation on the heart are dependent on dose, fractionation, overall treatment time, and pre-existing cardiovascular pathology. Murine models have played a central role in improving our understanding of the radiation response of the heart yet a wide range of exposure parameters have been used. We evaluated the study design of published murine cardiac irradiation experiments to assess gaps in the literature and to suggest guidance for the harmonisation of future study reporting.

METHODS AND MATERIALS

A systematic review of mouse/rat studies published 1981-2021 that examined the effect of radiation on the heart was performed. The protocol was published on PROSPERO (CRD42021238921) and the findings were reported in accordance with the PRISMA guidance. Risk of bias was assessed using the SYRCLE checklist.

RESULTS

159 relevant full-text original articles were reviewed. The heart only was the target volume in 67% of the studies and simulation details were unavailable for 44% studies. Dosimetry methods were reported in 31% studies. The pulmonary effects of whole and partial heart irradiation were reported in 13% studies. Seventy-eight unique dose-fractionation schedules were evaluated. Large heterogeneity was observed in the endpoints measured, and the reporting standards were highly variable.

CONCLUSIONS

Current murine models of radiation cardiotoxicity cover a wide range of irradiation configurations and latency periods. There is a lack of evidence describing clinically relevant dose-fractionations, circulating biomarkers and radioprotectants. Recommendations for the consistent reporting of methods and results of in vivo cardiac irradiation studies are made to increase their suitability for informing the design of clinical studies.

Racial disparities in mortality outcomes among women diagnosed with breast cancer in Maryland: Impact of cardiovascular disease and clinical characteristics

BACKGROUND

Although racial disparities in breast cancer (BC) mortality have been well documented in the United States, little is known about the impact of coexisting cardiovascular disease (CVD) and other clinical factors on Black-White survival disparities after the diagnosis of BC. This study examined the associations of race, CVD, and clinical factors at diagnosis with the hazard of BC and CVD-related mortality among patients with BC identified from the Maryland Cancer Registry.

METHODS

A total of 36,088 women (25,181 Whites and 10,907 Blacks) diagnosed with incident invasive BC between 2007 and 2017 were included. Subdistribution hazard ratios (sdHRs) for CVD-related and BC mortality were estimated with Fine and Gray regression models, which accounted for the influence of competing events.

RESULTS

After a median follow-up of 5.8 years, 8019 deaths occurred; 3896 were BC deaths, and 1167 deaths were CVD-related. Black women had a higher hazard of BC mortality (sdHR, 1.66; 95% confidence interval [CI], 1.55-1.77) and CVD mortality (sdHR, 1.33; 95% CI, 1.17-1.51) in comparison with White women. Associations with CVD mortality were significantly stronger among Black women aged 50 to 59 years (sdHR, 2.86; 95% CI, 1.84-4.44; P for interaction < .001). Among Black women with CVD, the hazard of BC death was 41% higher in comparison with White women. By treatment, a significant association with CVD mortality was observed only among Black women undergoing surgery and radiation (sdHR, 1.61; 95% CI, 1.22-2.13).

CONCLUSIONS

Clinicians should consider the impact of younger age, preexisting CVD, and BC treatments among Black patients. Early identification of those at risk for worse survival may improve surveillance and outcomes.

Quantitative assessment of intra- and inter-modality deformable image registration of the heart, left ventricle, and thoracic aorta on longitudinal 4D-CT and MR images

Purpose

Magnetic resonance imaging (MRI)‐based investigations into radiotherapy (RT)‐induced cardiotoxicity require reliable registrations of magnetic resonance (MR) imaging to planning computed tomography (CT) for correlation to regional dose. In this study, the accuracy of intra‐ and inter‐modality deformable image registration (DIR) of longitudinal four‐dimensional CT (4D‐CT) and MR images were evaluated for heart, left ventricle (LV), and thoracic aorta (TA).

Methods and materials

Non‐cardiac‐gated 4D‐CT and T1 volumetric interpolated breath‐hold examination (T1‐VIBE) MRI datasets from five lung cancer patients were obtained at two breathing phases (inspiration/expiration) and two time points (before treatment and 5 weeks after initiating RT). Heart, LV, and TA were manually contoured. Each organ underwent three intramodal DIRs ((A) CT modality over time, (B) MR modality over time, and (C) MR contrast effect at the same time) and two intermodal DIRs ((D) CT/MR multimodality at same time and (E) CT/MR multimodality over time). Hausdorff distance (HD), mean distance to agreement (MDA), and Dice were evaluated and assessed for compliance with American Association of Physicists in Medicine (AAPM) Task Group (TG)‐132 recommendations.

Results

Mean values of HD, MDA, and Dice under all registration scenarios for each region of interest ranged between 8.7 and 16.8 mm, 1.0 and 2.6 mm, and 0.85 and 0.95, respectively, and were within the TG‐132 recommended range (MDA < 3 mm, Dice > 0.8). Intramodal DIR showed slightly better results compared to intermodal DIR. Heart and TA demonstrated higher registration accuracy compared to LV for all scenarios except for HD and Dice values in Group A. Significant differences for each metric and tissue of interest were noted between Groups B and D and between Groups B and E. MDA and Dice significantly differed between LV and heart in all registrations except for MDA in Group E.

Conclusions

DIR of the heart, LV, and TA between non‐cardiac‐gated longitudinal 4D‐CT and MRI across two modalities, breathing phases, and pre/post‐contrast is acceptably accurate per AAPM TG‐132 guidelines. This study paves the way for future evaluation of RT‐induced cardiotoxicity and its related factors using multimodality DIR.

Cardiologic Long-Term Follow-Up of Patients Treated With Chest Radiotherapy: When and How?

Introduction: Radiotherapy may cause valvular (VHD), pericardial, coronary artery disease (CAD), left ventricular dysfunction (LVD), arrhythmias. The risk of radiation induced heart disease (RIHD) increases over time. The current guidelines suggest a screening for RIHD every 5 years in the long-term survivors who had been treated by chest RT.

Methods: We reviewed the clinical and instrumental data of 106 patients diagnosed with RIHD. In one group (Group A: 69 patients) RIHD was diagnosed in an asymptomatic phase through a screening with ECG, echocardiogram and stress test. A second group (37 patients) was seen when RIHD was symptomatic. We compared the characteristics of the two groups at the time of RT, of RIHD detection and at last follow-up.

Results: Overall, 64 patients (60%) had CAD (associated to other RIHD in 18); 39 (36.7%) had LVD (isolated in 20); 24 (22.6%) had VHD (isolated in 10 cases). The interval between the last negative test and the diagnosis of moderate or severe RIHD was <5 years in 26 patients, and <4 years in 18. In group A, 63% of the patients with CAD had silent ischemia. The two groups did not differ with regard to type of tumor, cardiovascular risk factors, use of anthracycline-based chemotherapy, age at RT treatment, radiation dose and interval between RT and toxicity detection. The mean time from RT and RIHD was 16 years in group A and 15 in group B. Interventional therapy at RIHD diagnosis was more frequent in group B (54 vs. 30%, p < 0.05). At last follow-up, 27 patients had died (12 of cancer, 9 of cardiac causes, 6 of other causes); mean ejection fraction was 60% in group A and 50% in group B (p < 0.01). Patients with ejection fraction ≤ 50% were 14.5% in group A and 40% in group B (p < 0.01).

Conclusions: Clinically relevant RIHD become evident at a mean interval of 16 years after RT. The most frequent clinical manifestations are CAD and LVD. RIHD diagnosis in asymptomatic patients may preserve their cardiac function with timely interventions. We suggest -after 10 years from radiotherapy- a screening every 2–3 years.

Leveraging Radiobiology for Arrhythmia Management: A New Treatment Paradigm?

Radiation therapy is a well-established approach for safely and non-invasively treating solid tumours and benign diseases with high precision and accuracy. Cardiac radiation therapy has recently emerged as a non-invasive treatment option for the management of refractory ventricular tachycardia. Here we summarise existing clinical and preclinical literature surrounding cardiac radiobiology and discuss how these studies may inform basic and translational research, as well as clinical treatment paradigms in the management of arrhythmias.

Past, Present, and Future of Radiation-Induced Cardiotoxicity: Refinements in Targeting, Surveillance, and Risk Stratification

Radiation therapy is an important component of cancer therapy for many malignancies. With improvements in cardiac-sparing techniques, radiation-induced cardiac dysfunction has decreased but remains a continued concern. In this review, we provide an overview of the evolution of radiotherapy techniques in thoracic cancers and associated reductions in cardiac risk. We also highlight data demonstrating that in some cases radiation doses to specific cardiac substructures correlate with cardiac toxicities and/or survival beyond mean heart dose alone. Advanced cardiac imaging, cardiovascular risk assessment, and potentially even biomarkers can help guide post-radiotherapy patient care. In addition, treatment of ventricular arrhythmias with the use of ablative radiotherapy may inform knowledge of radiation-induced cardiac dysfunction. Future efforts should explore further personalization of radiotherapy to minimize cardiac dysfunction by coupling knowledge derived from enhanced dosimetry to cardiac substructures, post-radiation regional dysfunction seen on advanced cardiac imaging, and more complete cardiac toxicity data.

Using Novel Statistical Techniques to Accurately Determine the Predictive Dose Range in a Study of Overall Survival after Definitive Radiotherapy for Stage III Non-Small Cell Lung Cancer in Association with Heart Dose

PURPOSE

Recent studies of radiotherapy (RT) for stage III non-small-cell lung cancer (NSCLC) have associated high dose to the heart with cardiac toxicity and decreased overall survival (OS). We used advanced statistical techniques to account for correlations between dosimetric variables and more accurately determine the range of heart doses which are associated with reduced OS in patients receiving RT for stage III NSCLC.

METHODS

From 2006 to 2013, 119 patients with stage III NSCLC received definitive RT at our institution. OS data was obtained from institutional tumor registry. We used multivariate Cox model to determine patient specific covariates predictive for reduced overall survival. We examined age, prescription dose, mean lung dose, lung V20, RT technique, stage, chemotherapy, tumor laterality, tumor volume, and tumor site as candidate covariates. We subsequently used novel statistical techniques within multivariate Cox model to systematically search the whole heart dose-volume histogram (DVH) for dose parameters associated with OS.

RESULTS

Patients were followed until death or 2.5 to 81.2 months (median 30.4 months) in those alive at last follow up. On multivariate analysis of whole heart DVH, the dose of 51 Gy was identified as a threshold dose above which the dose volume relationship becomes predictive for OS. We identified V55Gy (percentage of the whole heart volume receiving at least 55 Gy) as the best single DVH index which can be used to set treatment optimization constraints (Hazard Ratio = 1.044 per 1% increase in heart volume exposed to at least 55 Gy, P = 0.03). Additional characteristics correlated with OS on multivariate analysis were age, stage (IIIA/IIIB), and administration of chemotherapy.

CONCLUSION

Doses above 51 Gy, applied to small volumes of the heart, are associated with worse OS in stage III NSCLC patients treated with definitive RT. Higher stage, older age and lack of chemotherapy were also associated with reduced OS.

Assessment of Prognostic Value of High-Sensitivity Cardiac Troponin T for Early Prediction of Chemoradiation Therapy-Induced Cardiotoxicity in Patients with Non-Small Cell Lung Cancer: A Secondary Analysis of a Prospective Randomized Trial

PURPOSE

Cardiotoxicities induced by cancer therapy can negatively affect quality of life and survival. We investigated whether high-sensitivity cardiac troponin T (hs-cTnT) levels could serve as biomarker for early detection of cardiac adverse events (CAEs) after chemoradiation therapy (CRT) for non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

This study included 225 patients who received concurrent platinum and taxane-doublet chemotherapy with thoracic radiation therapy to a total dose of 60 to 74 Gy for NSCLC. All patients were evaluated for CAEs; 190 patients also had serial hs-cTnT measurements.

RESULTS

Grade ≥3 CAEs occurred in 24 patients (11%) at a median interval of 9 months after CRT. Pretreatment hs-cTnT levels were higher in men, in patients aged ≥64 years, and in patients with pre-existing heart disease or poor performance status (P < .05). hs-cTnT levels increased at 4 weeks during CRT (P < .05) and decreased after completion of CRT but did not return to pretreatment levels (P = .002). The change (Δ) in hs-cTnT levels during CRT correlated with mean heart dose (P = .0004), the heart volumes receiving 5 to 55 Gy (P < .05), and tumor location (P = .006). Risks of severe CAEs and mortality were significantly increased if the pretreatment hs-cTnT was >10 ng/L or the Δ during CRT was ≥5 ng/L.

CONCLUSIONS

Elevation of hs-cTnT during CRT was radiation heart dose-dependent, and high hs-cTnT levels during the course of CRT were associated with CAEs and mortality. Routine monitoring of hs-cTnT could identify patients who are at high risk of CRT-induced CAEs early to guide modifications of cancer therapy and possible interventions to mitigate cardiotoxicity.

DNA damage response in vascular endothelial senescence: Implication for radiation-induced cardiovascular diseases

A post-exposure cohort study in Hiroshima and Nagasaki reported that low-dose exposure to radiation heightened the risk of cardiovascular diseases (CVD), such as stroke and myocardial infarction, by 14-18% per Gy. Moreover, the risk of atherosclerosis in the coronary arteries reportedly increases with radiation therapy of the chest, including breast and lung cancer treatment. Cellular senescence of vascular endothelial cells (ECs) is believed to play an important role in radiation-induced CVDs. The molecular mechanism of age-related cellular senescence is believed to involve genomic instability and DNA damage response (DDR); the chronic inflammation associated with senescence causes cardiovascular damage. Therefore, vascular endothelial cell senescence is believed to induce the pathogenesis of CVDs after radiation exposure. The findings of several prior studies have revealed that ionizing radiation (IR) induces cellular senescence as well as cell death in ECs. We have previously reported that DDR activates endothelial nitric oxide (NO) synthase, and NO production promotes endothelial senescence. Endothelial NO synthase (eNOS) is a major isoform expressed in ECs that maintains cardiovascular homeostasis. Therefore, radiation-induced NO production, a component of the DDR in ECs, may be involved in CVDs after radiation exposure. In this article, we describe the pathology of radiation-induced CVD and the unique radio-response to radiation exposure in ECs.

3-Year Follow-Up of Radiation-Associated Changes in Diastolic Function by Speckle Tracking Echocardiography

Background

Radiation therapy (RT) results in myocardial changes consisting of diffuse fibrosis, which may result in changes in diastolic function.

Objectives

The aim of this study was to explore RT-associated changes in left ventricular (LV) diastolic function.

Methods

Sixty chemotherapy-naive patients with left-sided, early-stage breast cancer were studied with speckle tracking echocardiography at 3 time points: prior to, immediately after, and 3 years after RT. Global and regional early diastolic strain rate (SRe) were quantified, as were parameters of systolic function.

Results

Regional changes in SRe, particularly the apical and anteroseptal segments, were observed over time and were more evident than global changes. The apical SRe declined from a median of 1.24 (interquartile range: 1.01 to 1.39) s^-1 at baseline to 1.02 (interquartile range: 0.79 to 1.15) s^-1 at 3 years of follow-up (p < 0.001). This decline was associated with the left ventricular maximal radiation dose (β = 0.36, p = 0.007). The global SRe was <1.00 s^-1 (SRe_dep) in 11 (18.3%) patients at baseline, 21 (35%) patients (p = 0.013) post-RT, and 17 (28.3%) patients (p = 0.051) at 3 years. SRe_dep post-RT was independently associated with baseline cardiac abnormalities (odds ratio: 0.26; 95% confidence interval: 0.08 to 0.84; p = 0.025); SRe_dep at 3 years of follow-up was associated with the baseline Charlson comorbidity index (odds ratio: 2.36; 95% confidence interval: 1.17 to 4.77; p = 0.017). Diastolic function abnormalities were evident even in patients with preserved global longitudinal strain at 3 years.

Conclusions

RT resulted in changes in the SRe in the apical and anteroseptal segments over 3 years of follow-up. Changes in SRe apical segments were present even in patients with preserved systolic function and were independently associated with RT dose and cardiovascular comorbidities.

Cardio-Oncology: A Continually Evolving Subspecialty in Oncology Nursing

Cardio-oncology is a unique subspecialty within oncology nursing that focuses on the assessment, identification, and management of cardiotoxicity induced or exacerbated by cancer treatment. Nurses are pivotal to the delivery of evidence-based assessment of and care for individuals who have preexisting cardiac conditions, as well as those for whom cardiac complications are related to the known and emerging toxicities of cancer treatment.

Radiotherapy in Early-stage Gastric MALT: Improved Survival Without Increased Cardiac Death

PURPOSE

Radiotherapy (RT) is an effective treatment for localized gastric mucosa-associated lymphoid tissue (MALT) lymphomas unresponsive to antibiotic therapy; however, irradiating the stomach can result in significant radiation to the heart, a risk factor for cardiac disease. We analyzed the Surveillance, Epidemiology, and End Results database to evaluate outcomes related to cardiac disease among patients treated with RT for stage I gastric MALT.

MATERIALS AND METHODS

We identified adult patients treated between 1993 and 2014. The relationship between treatment modality (RT, chemotherapy, combination, and no treatment) and overall survival (OS), mucosa-associated lymphoid tissue-specific survival (MSS), non-mucosa-associated lymphoid tissue-specific survival (non-MSS), and cardiac-specific survival (CSS) was assessed using the Kaplan-Meier estimator and Cox proportional hazards analyses.

RESULTS

A total of 2996 patients (median follow-up, 5.6 y) were analyzed: 27.5% had received RT alone, 12.1% chemotherapy alone, 3.9% chemoradiotherapy, and 56.5% no/unknown treatment (including antibiotic therapy). Compared with RT alone, patients who received chemotherapy alone exhibited worse OS (hazard ratio [HR]: 1.67; 95% confidence interval [CI]: 1.32-2.10; P<0.001) and MSS (HR: 2.10; 95% CI: 1.36-3.23; P=0.001). Although CSS appeared worse in patients who received chemotherapy (HR: 1.56; 95% CI: 0.92-2.66; P=0.10), it was not statistically significant. When comparing orbital and gastric MALT patients, there was no significant difference in CSS (HR: 0.80; 95% CI: 0.49-1.31; P=0.38).

CONCLUSIONS

RT improved survival among patients with stage I gastric MALT without increasing the risk of cardiac death. Those with gastric MALT exhibited similar CSS to those with orbital MALT. Although we cannot analyze nonfatal cardiac toxicity, these results suggest that, absent antibiotic therapy, RT should remain first-line treatment for early-stage gastric MALT.

Proton vs photon: A model-based approach to patient selection for reduction of cardiac toxicity in locally advanced lung cancer

PURPOSE/OBJECTIVE

To use a model-based approach to identify a sub-group of patients with locally advanced lung cancer who would benefit from proton therapy compared to photon therapy for reduction of cardiac toxicity.

MATERIAL/METHODS

Volumetric modulated arc photon therapy (VMAT) and robust-optimised intensity modulated proton therapy (IMPT) plans were generated for twenty patients with locally advanced lung cancer to give a dose of 70 Gy (relative biological effectiveness (RBE)) in 35 fractions. Cases were selected to represent a range of anatomical locations of disease. Contouring, treatment planning and organs-at-risk constraints followed RTOG-1308 protocol. Whole heart and ub-structure doses were compared. Risk estimates of grade⩾3 cardiac toxicity were calculated based on normal tissue complication probability (NTCP) models which incorporated dose metrics and patients baseline risk-factors (pre-existing heart disease (HD)).

RESULTS

There was no statistically significant difference in target coverage between VMAT and IMPT. IMPT delivered lower doses to the heart and cardiac substructures (mean, heart V5 and V30, P < .05). In VMAT plans, there were statistically significant positive correlations between heart dose and the thoracic vertebral level that corresponded to the most inferior limit of the disease. The median level at which the superior aspect of the heart contour began was the T7 vertebrae. There was a statistically significant difference in dose (mean, V5 and V30) to the heart and all substructures (except mean dose to left coronary artery and V30 to sino-atrial node) when disease overlapped with or was inferior to the T7 vertebrae. In the presence of pre-existing HD and disease overlapping with or inferior to the T7 vertebrae, the mean estimated relative risk reduction of grade⩾3 toxicities was 24-59%.

CONCLUSION

IMPT is expected to reduce cardiac toxicity compared to VMAT by reducing dose to the heart and substructures. Patients with both pre-existing heart disease and tumour and nodal spread overlapping with or inferior to the T7 vertebrae are likely to benefit most from proton over photon therapy.

Contemporary Understandings of Cardiovascular Disease After Cancer Radiotherapy: a Focus on Ischemic Heart Disease

PURPOSE OF REVIEW

Radiation-induced cardiovascular disease, including coronary artery disease, is a well-known sequela of radiation therapy and represents a significant source of morbidity and mortality for cancer survivors. This review examines current literature and guidelines to care for this growing population of cancer survivors.

RECENT FINDINGS

The development of radiation-induced ischemic heart disease following radiation can lead even to early cardiotoxicities, inclusive of coronary artery disease, which limit cancer treatment outcomes. These coronary lesions tend to be diffuse, complex, and proximal. Early detection with multimodality imaging and targeted intervention is required to minimize these risks. Early awareness, detection, and management of radiation-induced cardiovascular disease are paramount as cancer survivorship continues to grow.

Reduced increase of calcium scores using breath-hold in left-sided whole breast irradiation

PURPOSE

In this prospective longitudinal study, Coronary Artery Calcium (CAC) scores determined before the start of whole breast irradiation were compared with those determined 7 years afterwards. The aim was to examine whether the use of a breath-hold (BH) technique is associated with less increase of CAC scores.

METHODS AND MATERIALS

Changes in CAC scores were analysed in 87 breast cancer patients. The results of the following groups were compared: patients receiving right (R) or left-sided radiotherapy using free breathing (L-FB) with those receiving left-sided radiotherapy with BH (L-BH). We compared the changes of CAC scores between these groups over time, testing the hypothesis that a significantly reduced increase of calcium scores is observed when using BH.

RESULTS

For L-BH cases, when compared with L-FB cases, for overall as well as for Left Anterior Descending coronary artery (LAD) CAC scores, we noted significantly less increased CAC scores (p < 0.01). This effect of BH was even more striking in the group with CAC scores >0 at baseline. The attenuated increase over time of CAC scores in the L-BH group was robust to correction for age and statin use (p < 0.05).

CONCLUSION

After a median follow-up of 7.4 years, we found significantly less increased CAC scores when using BH. This is a relevant finding since higher levels of CAC scores are associated with higher probabilities of coronary artery events. Moreover, it underlines the rationale for the use of BH in left-sided whole breast irradiation.

Acute toxicities after proton beam therapy following breast-conserving surgery for breast cancer: Multi-institutional prospective PCG registry analysis

We investigated adverse events (AEs) and clinical outcomes for proton beam therapy (PBT) after breast-conserving surgery (BCS) for breast cancer. From 2012 to 2016, 82 patients received PBT in the prospective multi-institutional Proton Collaborative Group registry. AEs were recorded prospectively at each institution. Median follow-up was 8.1 months. Median dose was 50.4 Gy in 28 fractions. Most patients received a lumpectomy bed boost (90%) and regional nodal irradiation (RNI)(83%). Six patients (7.3%) experienced grade 3 AEs (5 with dermatitis, 5 with breast pain). Body mass index (BMI) was associated with grade 3 dermatitis (P = .015). Fifty-eight patients (70.7%) experienced grade ≥2 dermatitis. PBT including RNI after BCS is well-tolerated. Elevated BMI is associated with grade 3 dermatitis.

Perioperative Cardiothoracic and Vascular Risk in Childhood Cancer and its Survivors

CHILDREN with cancer and survivors of childhood cancer have an increased risk of cardiovascular disease, and this risk in the perioperative period must be understood. During diagnosis and treatment of pediatric cancer, multiple acute cardiovascular morbidities are possible, including anterior mediastinal mass, tamponade, hypertension, cardiomyopathy,and heart failure. Childhood cancer survivors reaching late childhood and adulthood experience substantially increased rates of cardiomyopathy, heart failure, valvular disease, pericardiac disease, ischemia, and arrhythmias. Despite considerable advances in the understanding and therapeutic options of pediatric malignancies, cardiac disease remains the most common treatment-related, noncancer cause of death in childhood cancer survivors. Increasingly, molecularly targeted agents, including small molecule inhibitors, are being incorporated into pediatric oncology. The acute and chronic risks associated with these newer therapeutic options in children are not yet well-described, which poses challenges for clinicians caring for these patients. In the present review, the unique risks factors, prevention strategies, and treatment of cardiovascular toxicities of the child with cancer and the childhood cancer survivor are examined, with an emphasis on the perioperative period.

Is an analytical dose engine sufficient for intensity modulated proton therapy in lung cancer?

OBJECTIVE

To identify a subgroup of lung cancer plans where the analytical dose calculation (ADC) algorithm may be clinically acceptable compared to Monte Carlo (MC) dose calculation in intensity modulated proton therapy (IMPT).

METHODS

Robust-optimised IMPT plans were generated for 20 patients to a dose of 70 Gy (relative biological effectiveness) in 35 fractions in Raystation. For each case, four plans were generated: three with ADC optimisation using the pencil beam (PB) algorithm followed by a final dose calculation with the following algorithms: PB (PB-PB), MC (PB-MC) and MC normalised to prescription dose (PB-MC scaled). A fourth plan was generated where MC optimisation and final dose calculation was performed (MC-MC). Dose comparison and γ analysis (PB-PB vs PB-MC) at two dose thresholds were performed: 20% (D20) and 99% (D99) with PB-PB plans as reference.

RESULTS

Overestimation of the dose to 99% and mean dose of the clinical target volume was observed in all PB-MC compared to PB-PB plans (median: 3.7 Gy(RBE) (5%) (range: 2.3 to 6.9 Gy(RBE)) and 1.8 Gy(RBE) (3%) (0.5 to 4.6 Gy(RBE))). PB-MC scaled plans resulted in significantly higher CTVD2 compared to PB-PB (median difference: -4 Gy(RBE) (-6%) (-5.3 to -2.4 Gy(RBE)), p ≤ .001). The overall median γ pass rates (3%-3 mm) at D20 and D99 were 93.2% (range:62.2-97.5%) and 71.3 (15.4-92.0%). On multivariate analysis, presence of mediastinal disease and absence of range shifters were significantly associated with high γ pass rates. Median D20 and D99 pass rates with these predictors were 96.0% (95.3-97.5%) and 85.4% (75.1-92.0%). MC-MC achieved similar target coverage and doses to OAR compared to PB-PB plans.

CONCLUSION

In the presence of mediastinal involvement and absence of range shifters Raystation ADC may be clinically acceptable in lung IMPT. Otherwise, MC algorithm would be recommended to ensure accuracy of treatment plans.

ADVANCES IN KNOWLEDGE

Although MC algorithm is more accurate compared to ADC in lung IMPT, ADC may be clinically acceptable where there is mediastinal involvement and absence of range shifters.

Emerging Challenges of Radiation-Associated Cardiovascular Dysfunction (RACVD) in Modern Radiation Oncology: Clinical Practice, Bench Investigation, and Multidisciplinary Care

Radiotherapy (RT) is a crucial treatment modality in managing cancer patients. However, irradiation dose sprinkling to tumor-adjacent normal tissues is unavoidable, generating treatment toxicities, such as radiation-associated cardiovascular dysfunction (RACVD), particularly for those patients with combined therapies or pre-existing adverse features/comorbidities. Radiation oncologists implement several efforts to decrease heart dose for reducing the risk of RACVD. Even applying the deep-inspiration breath-hold (DIBH) technique, the risk of RACVD is though reduced but still substantial. Besides, available clinical methods are limited for early detecting and managing RACVD. The present study reviewed emerging challenges of RACVD in modern radiation oncology, in terms of clinical practice, bench investigation, and multidisciplinary care. Several molecules are potential for serving as biomarkers and therapeutic targets. Of these, miRNAs, endogenous small non-coding RNAs that function in regulating gene expression, are of particular interest because low-dose irradiation, i.e., 200 mGy (one-tenth of conventional RT daily dose) induces early changes of pro-RACVD miRNA expression. Moreover, several miRNAs, e.g., miR-15b and miR21, involve in the development of RACVD, further demonstrating the potential bio-application in RACVD. Remarkably, many RACVDs are late RT sequelae, characterizing highly irreversible and progressively worse. Thus, multidisciplinary care from oncologists and cardiologists is crucial. Combined managements with commodities control (such as hypertension, hypercholesterolemia, and diabetes), smoking cessation, and close monitoring are recommended. Some agents show abilities for preventing and managing RACVD, such as statins and angiotensin-converting enzyme inhibitors (ACEIs); however, their real roles should be confirmed by further prospective trials.

Cardiotoxicity of mediastinal radiotherapy

Aim

To explore available recent literature related to cardiotoxicity following mediastinal radiation.

Background

Radiotherapy-related heart injury is well documented, with no apparent safety threshold dose. The number of long-term cancer survivors exposed to mediastinal radiotherapy at some point of their treatment is increasing. Heart dosimetric parameters are of great importance in developing a treatment plan, but few data are available regarding radiosensitivity and dose-volume constraints for specific heart structures.

Materials and Methods

In October 2018, we identified articles published after 1990 through a PubMed/MEDLINE database search. The authors examined rough search results and manuscripts not relevant for the topic were excluded. We extracted clinical outcomes following mediastinal radiotherapy of childhood cancers, lymphoma, medulloblastoma, thymic cancers and hematopoietic cell transplantation survivors and evaluated treatment planning data, whenever available.

Results

A total of 1311 manuscripts were identified in our first-round search. Of these manuscripts, only 115 articles, matching our selection criteria, were included.

Conclusions

Studies uniformly show a linear radiation dose-response relationship between mean absorbed dose to the heart (heart-D_mean) and the risk of dying as a result of cardiac disease, particularly when heart-D_mean exceeds 5 Gy. Limited data are available regarding dose-volume predictors for heart substructures and the risk of subsequent cardiac toxicity. An individual patient's cardiotoxicity risk can be modified with advanced treatment planning techniques, including deep inspiration breath hold. Proton therapy is currently showing advantages in improving treatment planning parameters when compared to advanced photon techniques in lymphoma, thymic malignancies, malignant mesothelioma and craniospinal irradiation.

Radiation-Associated Pericardial Disease

PURPOSE OF REVIEW

This review highlights the literature related to pericardial injury following radiation for oncologic diseases.

RECENT FINDINGS

Radiation-associated pericardial disease can have devastating consequences. Unfortunately, there is considerably less evidence regarding pericardial syndromes following thoracic radiation as compared to other cardiovascular outcomes. Pericardial complications of radiation may arise acutely or have an insidious onset several decades after treatment. Transthoracic echocardiography is the screening imaging modality of choice, while cardiac magnetic resonance imaging further characterizes the pericardium and guides treatment decision-making. Cardiac CT can be useful for assessing pericardial calcification. Ongoing efforts to lessen inadvertent cardiac injury are directed towards the revision of radiation techniques and protocols. As survival of mediastinal and thoracic malignancies continues to improve, radiation-associated pericardial disease is increasingly relevant. Though advances in radiation oncology demonstrate promise in curtailing cardiotoxicity, the long-term effects pertaining to pericardial complications remain to be seen.

Leveraging the Cardio-Protective and Anticancer Properties of Resveratrol in Cardio-Oncology

Cardio-oncology is a clinical/scientific discipline which aims to prevent and/or treat cardiovascular diseases in cancer patients. Although a large number of cancer treatments are known to cause cardiovascular toxicity, they are still widely used because they are highly effective. Unfortunately, therapeutic interventions to prevent and/or treat cancer treatment-induced cardiovascular toxicity have not been established yet. A major challenge for such interventions is to protect the cardiovascular system without compromising the therapeutic benefit of anticancer medications. Intriguingly, the polyphenolic natural compound resveratrol and its analogs have been shown in preclinical studies to protect against cancer treatment-induced cardiovascular toxicity. They have also been shown to possess significant anticancer properties on their own, and to enhance the anticancer effect of other cancer treatments. Thus, they hold significant promise to protect the cardiovascular system and fight the cancer at the same time. In this review, we will discuss the current knowledge regarding the cardio-protective and the anticancer properties of resveratrol and its analogs. Thereafter, we will discuss the challenges that face the clinical application of these agents. To conclude, we will highlight important gaps of knowledge and future research directions to accelerate the translation of these exciting preclinical findings to cancer patient care.