Radiation-induced heart disease: a clinical update

Dexmedetomidine ameliorates x-ray-induced myocardial injury via alleviating cardiomyocyte apoptosis and autophagy

BACKGROUND

Radiotherapy is a primary local treatment for tumors, yet it may lead to complications such as radiation-induced heart disease (RIHD). Currently, there is no standardized approach for preventing RIHD. Dexmedetomidine (Dex) is reported to have cardio-protection effects, while its role in radiation-induced myocardial injury is unknown. In the current study, we aimed to evaluate the radioprotective effect of dexmedetomidine in X-ray radiation-treated mice.

METHODS

18 male mice were randomized into 3 groups: control, 16 Gy, and 16 Gy + Dex. The 16 Gy group received a single dose of 16 Gy X-ray radiation. The 16 Gy + Dex group was pretreated with dexmedetomidine (30 µg/kg, intraperitoneal injection) 30 min before X-ray radiation. The control group was treated with saline and did not receive X-ray radiation. Myocardial tissues were collected 16 weeks after X-ray radiation. Hematoxylin-eosin staining was performed for histopathological examination. Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining was performed to assess the state of apoptotic cells. Immunohistochemistry staining was performed to examine the expression of CD34 molecule and von Willebrand factor. Besides, western blot assay was employed for the detection of apoptosis-related proteins (BCL2 apoptosis regulator and BCL2-associated X) as well as autophagy-related proteins (microtubule-associated protein 1 light chain 3, beclin 1, and sequestosome 1).

RESULTS

The findings demonstrated that 16 Gy X-ray radiation resulted in significant changes in myocardial tissues, increased myocardial apoptosis, and activated autophagy. Pretreatment with dexmedetomidine significantly protects mice against 16 Gy X-ray radiation-induced myocardial injury by inhibiting apoptosis and autophagy.

CONCLUSION

In summary, our study confirmed the radioprotective effect of dexmedetomidine in mitigating cardiomyocyte apoptosis and autophagy induced by 16 Gy X-ray radiation.

Radiation Therapy for Lung Cancer: Imaging Appearances and Pitfalls

Radiation therapy is part of a multimodality treatment approach to lung cancer. The radiologist must be aware of both the expected and the unexpected imaging findings of the post-radiation therapy patient, including the time course for development of post- radiation therapy pneumonitis and fibrosis. In this review, a brief discussion of radiation therapy techniques and indications is presented, followed by an image-heavy differential diagnostic approach. The review focuses on computed tomography imaging examples to help distinguish normal postradiation pneumonitis and fibrosis from alternative complications, such as infection, local recurrence, or radiation-induced malignancy.

Sex-Based Differences in Clinical Outcomes of Acute Coronary Syndrome Among Patients With Mediastinal Radiation Exposure: Insights From The National Inpatient Sample (2009-2020)

There is a paucity of data about the sex differences in acute coronary syndrome (ACS) outcomes in patients with prior mediastinal radiation. The National Inpatient Sample database from years 2009 to 2020 were queried for ACS hospitalizations of patients with prior mediastinal radiation. The primary outcome was MACCE (major cardiovascular events), and secondary outcomes included other clinical outcomes. A total of 23,385 hospitalizations for ACS with prior mediastinal radiation exposure ([15,904 (68.01%) females, and 7481 (31.99%) males]) were included in analysis. Males were slightly younger than females (median, age (70 [62-78] vs 72 [64-80]). Female patients with ACS had a higher burden of hypertension (80.82% vs 73.55%), diabetes mellitus (33% vs 28.35%), hyperlipidemia (66.09% vs 62.2%), obesity (17.02% vs 8.6%) however, males had a higher burden of peripheral vascular disease (18.29% vs 12.51%), congestive heart failure (41.8% vs 39.35%) and smoking (70.33% vs 46.92%). After propensity matching, primary outcome MACCE was higher in males (20.85% vs 13.29%, aOR: 1.80 95% CI (1.65-1.96), P < 0.0001) along with cardiogenic shock (8.74% vs 2.42%, aOR: 1.77 95% CI (1.55-2.02), P < 0.0001) and mechanical circulatory support use (aOR: 1.48 95% CI [1.29 -1.71], P < 0.0001). We observed no differences in the length of hospital stay, however total hospitalization cost was higher in males. This nationwide analysis showed significant disparities in outcomes among male and female ACS patients with prior mediastinal radiation history, with increasing trend in hospitalization for ACS among males and females but decreasing mortality among females.

Integrating subvolume dose and myocardial perfusion imaging parameters to assess the impact of radiation therapy on heart function in breast cancer patients: A comparative analysis between left- and right-sided breast cancer

BACKGROUND

This study aimed to utilize an innovative method of integrating the 20 subvolume dose of left ventricle and the Tl-201 single photon emission computed tomography (SPECT) with myocardial perfusion imaging (MPI) parameters in patients with left- and right-sided breast cancer after radiation therapy.

METHODS

Female patients with breast cancer underwent SPECT MPI before commencing radiotherapy and 12 months later were enrolled from January 2014 to December 2018. The images of CT simulation and SPECT MPI were integrated into the treatment planning system. The differences of doses and parameters of MPI in all cardiac subvolumes between left- and right-sided breast cancer patients were analyzed.

RESULTS

Patients with left-sided breast cancer (n = 61) received a higher radiation dose to the heart, left ventricular, and its territories and subvolumes, compared to patients with right-sided breast cancer (n = 19). The 20-segment analysis also showed statistically significant disparities in the average radiation doses received by the two groups. In different coronary artery territories, the end-diastolic perfusion and end-systolic perfusion showed a decrease in both sides, with no significant differences. However, the wall motion and wall thickening showed a significant decline in subregions within the left- and right-sided coronary artery territories.

CONCLUSION

This study demonstrates an innovative integrated method combining the left ventricular 20 regional doses with SPECT MPI which shows that left-sided breast cancer patients receive a higher subvolume dose than right-sided breast cancer patients. Further research is needed to confirm the potential impact on heart function after radiotherapy on both sides.

Evaluation of the cardiac subvolume dose and myocardial perfusion in left breast cancer patients with postoperative radiotherapy: a prospective study

Adjuvant breast radiotherapy could reduce the risk of local recurrence. However, the radiation dose received by the heart also increases the risk of cardiotoxicity and causes consequential heart diseases. This prospective study aimed to evaluate more precisely cardiac subvolume doses and corresponding myocardial perfusion defects according to the American Heart Association (AHA)'s 20-segment model for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) interpretation for breast cancer after radiotherapy. The 61 female patients who underwent adjuvant radiotherapy following breast cancer surgery for left breast cancer were enrolled. SPECT MPI were performed before radiotherapy for baseline study, and 12 months after for follow-up. Enrolled patients were divided into two groups, new perfusion defect (NPD) and non new perfusion defect found (non-NPD) according to myocardial perfusion scale score. CT simulation data, radiation treatment planning, and SPECT MPI images were fused and registered. The left ventricle was divided into four rings, three territories, and 20 segments according to the AHA's 20-segment model of the LV. The doses between NPD and non-NPD groups were compared by the Mann-Whitney test. The patients were divided into two groups: NPD group (n = 28) and non-NPD group (n = 33). The mean heart dose was 3.14 Gy in the NPD group and 3.08 Gy in the non-NPD group. Mean LV doses were 4.84 Gy and 4.71 Gy, respectively. The radiation dose of the NPD group was higher than the non-NPD group in the 20 segments of LV. There was significant difference in segment 3 (p = 0.03). The study indicated that the radiation doses to 20 segments of LV in NPD were higher than those in non-NPD significantly at segment 3, and higher in other segments in general. In the bull's eye plot combining radiation dose and NPD area, we found that the new cardiac perfusion decline may exist even in the low radiation dose region.Trial registration: FEMH-IRB-101085-F. Registered 01/01/2013, https://clinicaltrials.gov/ct2/show/NCT01758419?cond=NCT01758419&draw=2&rank=1 .

TLR4-A Pertinent Player in Radiation-Induced Heart Disease?

The heart is one of the organs that is sensitive to developing delayed adverse effects of ionizing radiation (IR) exposure. Radiation-induced heart disease (RIHD) occurs in cancer patients and cancer survivors, as a side effect of radiation therapy of the chest, with manifestation several years post-radiotherapy. Moreover, the continued threat of nuclear bombs or terrorist attacks puts deployed military service members at risk of exposure to total or partial body irradiation. Individuals who survive acute injury from IR will experience delayed adverse effects that include fibrosis and chronic dysfunction of organ systems such as the heart within months to years after radiation exposure. Toll-like receptor 4 (TLR4) is an innate immune receptor that is implicated in several cardiovascular diseases. Studies in preclinical models have established the role of TLR4 as a driver of inflammation and associated cardiac fibrosis and dysfunction using transgenic models. This review explores the relevance of the TLR4 signaling pathway in radiation-induced inflammation and oxidative stress in acute as well as late effects on the heart tissue and the potential for the development of TLR4 inhibitors as a therapeutic target to treat or alleviate RIHD.

Stereotactic Arrhythmia Radioablation Treatment of Ventricular Tachycardia: Current Technology and Evolving Indications

Ventricular tachycardia in patients with structural heart disease is a significant cause of morbidity and mortality. According to current guidelines, cardioverter defibrillator implantation, antiarrhythmic drugs, and catheter ablation are established therapies in the management of ventricular arrhythmias but their efficacy is limited in some cases. Sustained ventricular tachycardia can be terminated by cardioverter-defibrillator therapies although shocks in particular have been demonstrated to increase mortality and worsen patients' quality of life. Antiarrhythmic drugs have important side effects and relatively low efficacy, while catheter ablation, even if it is actually an established treatment, is an invasive procedure with intrinsic procedural risks and is frequently affected by patients' hemodynamic instability. Stereotactic arrhythmia radioablation for ventricular arrhythmias was developed as bail-out therapy in patients unresponsive to traditional treatments. Radiotherapy has been mainly applied in the oncological field, but new current perspectives have developed in the field of ventricular arrhythmias. Stereotactic arrhythmia radioablation provides an alternative non-invasive and painless therapeutic strategy for the treatment of previously detected cardiac arrhythmic substrate by three-dimensional intracardiac mapping or different tools. Since preliminary experiences have been reported, several retrospective studies, registries, and case reports have been published in the literature. Although, for now, stereotactic arrhythmia radioablation is considered an alternative palliative treatment for patients with refractory ventricular tachycardia and no other therapeutic options, this research field is currently extremely promising.

Successful treatment with ivabradine in a β-blocker-refractory patient with acute decompensated heart failure with reduced ejection fraction

Ivabradine is an established treatment for chronic heart failure with reduced ejection fraction (HFrEF); however, it is not used for acute heart failure treatment. Negative inotropic effects (NIE) often limit the up-titration of β-blockers. Contrarily, ivabradine has no NIE, and enables β-blockers usage for treating patients with acute decompensated HFrEF.

Right versus left breast radiation and coronary artery disease: is there a differential?

There is literature supporting the view that chest radiation (CR) for the management of primary or metastatic cancer of the mediastinum and chest, including breast cancer is associated with all types of heart disease, including coronary artery disease (CAD), manifesting during long-term follow-up. This review explores the literature about the association of CR for the management of cancer and CAD, particularly focussing on breast cancer, and further on the differential between CR for right versus left breast cancer. The balk of the literature suggests that there is higher incidence of CAD in patients undergoing left versus right-CR for breast cancer, and that cardiologists and oncologists need to become involved systematically in their assessment prior to CR and at subsequent follow-up.

Tissue Reactions and Mechanism in Cardiovascular Diseases Induced by Radiation

The long-term survival rate of cancer patients has been increasing as a result of advances in treatments and precise medical management. The evidence has accumulated that the incidence and mortality of non-cancer diseases have increased along with the increase in survival time and long-term survival rate of cancer patients after radiotherapy. The risk of cardiovascular disease as a radiation late effect of tissue damage reactions is becoming a critical challenge and attracts great concern. Epidemiological research and clinical trials have clearly shown the close association between the development of cardiovascular disease in long-term cancer survivors and radiation exposure. Experimental biological data also strongly supports the above statement. Cardiovascular diseases can occur decades post-irradiation, and from initiation and development to illness, there is a complicated process, including direct and indirect damage of endothelial cells by radiation, acute vasculitis with neutrophil invasion, endothelial dysfunction, altered permeability, tissue reactions, capillary-like network loss, and activation of coagulator mechanisms, fibrosis, and atherosclerosis. We summarize the most recent literature on the tissue reactions and mechanisms that contribute to the development of radiation-induced cardiovascular diseases (RICVD) and provide biological knowledge for building preventative strategies.

Myocardial Ischemia Related to Common Cancer Therapy-Prevention Insights

Modern antineoplastic therapy improves survival and quality of life in cancer patients, but its indisputable benefits are accompanied by multiple and major side effects, such as cardiovascular ones. Endothelial dysfunction, arterial spasm, intravascular thrombosis, and accelerated atherosclerosis affect the coronary arteries, leading to acute and chronic coronary syndromes that negatively interfere with the oncologic treatment. The cardiac toxicity of antineoplastic agents may be mitigated by using adequate prophylactic measures. In the absence of dedicated guidelines, our work provides the most comprehensive, systematized, structured, and up-to-date analyses of the available literature focusing on measures aiming to protect the coronary arteries from the toxicity of cancer therapy. Our work facilitates the implementation of these measures in daily practice. The ultimate goal is to offer clinicians the necessary data for a personalized therapeutic approach for cancer patients receiving evidence-based oncology treatments with potential cardiovascular toxicity.

Eleutheroside E supplementation prevents radiation-induced cognitive impairment and activates PKA signaling via gut microbiota

Radiation affects not only cognitive function but also gut microbiota. Eleutheroside E (EE), a principal active compound of Acanthopanax senticosus, has a certain protective effect on the nervous system. Here, we find a four-week EE supplementation to the ⁶⁰Co-γ ray irradiated mice improves the cognition and spatial memory impairments along with the protection of hippocampal neurons, remodels the gut microbiota, especially changes of Lactobacillus and Helicobacter, and altered the microbial metabolites including neurotransmitters (GABA, NE, ACH, 5-HT) as well as their precursors. Furthermore, the fecal transplantation of EE donors verifies that EE alleviated cognition and spatial memory impairments, and activates the PKA/CREB/BDNF signaling via gut microbiota. Our findings provide insight into the mechanism of EE effect on the gut-brain axis and underpin a proposed therapeutic value of EE in cognitive and memory impairments induced by radiation.

Radiation-Induced Cardiac Dysfunction: Optimizing Radiation Delivery and Postradiation Care

Radiation therapy (RT) is part of standard-of-care treatment of many thoracic cancers. More than 60% of patients receiving thoracic RT may eventually develop radiation-induced cardiac dysfunction (RICD) secondary to collateral heart dose. This article reviews factors contributing to a thoracic cancer patient's risk for RICD, including RT dose to the heart and/or cardiac substructures, other anticancer treatments, and a patient's cardiometabolic health. It is also discussed how automated tracking of these factors within electronic medical record environments may aid radiation oncologists and other treating physicians in their ability to prevent, detect, and/or treat RICD in this expanding patient population.

An overview of radiation-induced heart disease

Radiation therapy (RT) has dramatically improved cancer survival, leading to several inevitable complications. Unintentional irradiation of the heart can lead to radiation-induced heart disease (RIHD), including cardiomyopathy, pericarditis, coronary artery disease, valvular heart disease, and conduction system abnormalities. Furthermore, the development of RIHD is aggravated with the addition of chemotherapy. The screening, diagnosis, and follow-up for RIHD in patients who have undergone RT are described by the consensus guidelines from the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE). There is compelling evidence that chest RT can increase the risk of heart disease. Although the prevalence and severity of RIHD are likely to be reduced with modern RT techniques, the incidence of RIHD is expected to rise in cancer survivors who have been treated with old RT regimens. However, there remains a gap between guidelines and clinical practice. Currently, therapeutic modalities followed in the treatment of RIHD are similar to the non-irradiated population. Preventive measures mainly reduce the radiation dose and radiation volume of the heart. There is no concrete evidence to endorse the preventive role of statins, angiotensin-converting enzyme inhibitors, and antioxidants. This review summarizes the current evidence of RIHD subtypes and risk factors and suggests screening regimens, diagnosis, treatment, and preventive approaches.

Chest Pain in the Cancer Patient

Chest pain is one of the most common presenting symptoms in patients seeking care from a physician. Risk assessment tools and scores have facilitated prompt diagnosis and optimal management in these patients; however, it is unclear as to whether a standardised approach can adequately triage chest pain in cancer patients and survivors. This is of concern because cancer patients are often at an increased risk of cardiovascular mortality and morbidity given the shared risk factors between cancer and cardiovascular disease, compounded by the fact that certain anti-cancer therapies are associated with an increased risk of cardiovascular events that can persist for weeks and even years after treatment. This article describes the underlying mechanisms of the most common causes of chest pain in cancer patients with an emphasis on how their management may differ to that of non-cancer patients with chest pain. It will also highlight the role of the cardio-oncology team, who can aid in identifying cancer therapy-related cardiovascular side-effects and provide optimal multidisciplinary care for these patients.

Radiation-Induced Heart Disease

Cancer incidence and survivorship have had a rising tendency over the last two decades due to better treatment modalities. One of these is radiation therapy (RT), which is used in 20-55% of cancer patients, and its basic principle consists of inhibiting proliferation or inducing apoptosis of cancer cells. Classically, photon beam RT has been the mainstay therapy for these patients, but, in the last decade, proton beam has been introduced as a new option. This newer method focuses more on the tumor and affects less of the surrounding normal tissue, i.e., the heart. Radiation to the heart is a common complication of RT, especially in patients with lymphoma, breast, lung, and esophageal cancer. The pathophysiology is due to changes in the microvascular and macrovascular milieu that can promote accelerated atherosclerosis and/or induce fibrosis of the myocardium, pericardium, and valves. These complications occur days, weeks, or years after RT and the risk factors associated are high radiation doses (>30 Gy), concomitant chemotherapy (primarily anthracyclines), age, history of heart disease, and the presence of cardiovascular risk factors. The understanding of these mechanisms and risk factors by physicians can lead to a tailored assessment and monitorization of these patients with the objective of early detection or prevention of radiation-induced heart disease. Echocardiography is a noninvasive method which provides a comprehensive evaluation of the pericardium, valves, myocardium, and coronaries, making it the first imaging tool in most cases; however, other modalities, such as computed tomography, nuclear medicine, or cardiac magnetic resonance, can provide additional value.

Withaferin A: From Ancient Remedy to Potential Drug Candidate

Withaferin A (WA) is a pivotal withanolide that has conquered a conspicuous place in research, owning to its multidimensional biological properties. It is an abundant constituent in Withania somnifera Dunal. (Ashwagandha, WS) that is one of the prehistoric pivotal remedies in Ayurveda. This article reviews the literature about the pharmacological profile of WA with special emphasis on its anticancer aspect. We reviewed research publications concerning WA through four databases and provided a descriptive analysis of literature without statistical or qualitative analysis. WA has been found as an effective remedy with multifaceted mechanisms and a broad spectrum of pharmacological profiles. It has anticancer, anti-inflammatory, antiherpetic, antifibrotic, antiplatelet, profibrinolytic, immunosuppressive, antipigmentation, antileishmanial, and healing potentials. Evidence for wide pharmacological actions of WA has been established by both in vivo and in vitro studies. Further, the scientific literature accentuates the role of WA harboring a variable therapeutic spectrum for integrative cancer chemoprevention and cure. WA is a modern drug from traditional medicine that is necessary to be advanced to clinical trials for advocating its utility as a commercial drug.

Imaging of the Chest After Radiotherapy and Potential Pitfalls

Radiotherapy is one of the cornerstones for the treatment of thoracic malignancies. The goal of radiotherapy is to deliver maximal dose to the tumor while minimizing damage to surrounding normal anatomical structures. Although advances in radiotherapy technology have considerably improved radiation delivery, potential adverse effects are still common. Post radiation changes to the chest may include different structures such as the lung, heart, great vessels, and esophagus. The purpose of this manuscript is to illustrate the post radiotherapy changes to these anatomical structures resulting from external beam radiotherapy, as well as discuss imaging pitfalls to prevent radiologist's interpretation errors.

Nucleus-mitochondria positive feedback loop formed by ERK5 S496 phosphorylation-mediated poly (ADP-ribose) polymerase activation provokes persistent pro-inflammatory senescent phenotype and accelerates coronary atherosclerosis after chemo-radiation

The incidence of cardiovascular disease (CVD) is higher in cancer survivors than in the general population. Several cancer treatments are recognized as risk factors for CVD, but specific therapies are unavailable. Many cancer treatments activate shared signaling events, which reprogram myeloid cells (MCs) towards persistent senescence-associated secretory phenotype (SASP) and consequently CVD, but the exact mechanisms remain unclear. This study aimed to provide mechanistic insights and potential treatments by investigating how chemo-radiation can induce persistent SASP. We generated ERK5 S496A knock-in mice and determined SASP in myeloid cells (MCs) by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. Candidate SASP inducers were identified by high-throughput screening, using the ERK5 transcriptional activity reporter cell system. Various chemotherapy agents and ionizing radiation (IR) up-regulated p90RSK-mediated ERK5 S496 phosphorylation. Doxorubicin and IR caused metabolic changes with nicotinamide adenine dinucleotide depletion and ensuing mitochondrial stunning (reversible mitochondria dysfunction without showing any cell death under ATP depletion) via p90RSK-ERK5 modulation and poly (ADP-ribose) polymerase (PARP) activation, which formed a nucleus-mitochondria positive feedback loop. This feedback loop reprogramed MCs to induce a sustained SASP state, and ultimately primed MCs to be more sensitive to reactive oxygen species. This priming was also detected in circulating monocytes from cancer patients after IR. When PARP activity was transiently inhibited at the time of IR, mitochondrial stunning, priming, macrophage infiltration, and coronary atherosclerosis were all eradicated. The p90RSK-ERK5 module plays a crucial role in SASP-mediated mitochondrial stunning via regulating PARP activation. Our data show for the first time that the nucleus-mitochondria positive feedback loop formed by p90RSK-ERK5 S496 phosphorylation-mediated PARP activation plays a crucial role of persistent SASP state, and also provide preclinical evidence supporting that transient inhibition of PARP activation only at the time of radiation therapy can prevent future CVD in cancer survivors.

Stereotactic Arrhythmia Radioablation as a Novel Treatment Approach for Cardiac Arrhythmias: Facts and Limitations

Stereotactic ablative radiotherapy (SABR) is highly focused radiation therapy that targets well-demarcated, limited-volume malignant or benign tumors with high accuracy and precision using image guidance. Stereotactic arrhythmia radioablation (STAR) applies SABR to treat cardiac arrhythmias, including ventricular tachycardia (VT) and atrial fibrillation (AF), and has recently been a focus in research. Clinical studies have demonstrated electrophysiologic conduction blockade and histologic fibrosis after STAR, which provides a proof of principle for its potential for treating arrhythmias. This review will present the basic STAR principles, available clinical study outcomes, and how the technique has evolved since the first pre-clinical study. In addition to the clinical workflow, focus will be given on the process for stereotactic radiotherapy Quality Assurance (QA) tests, as well as the need for establishing a standardized QA protocol. Future implications and potential courses of research will also be discussed.

Multi-omic Analysis of Non-human Primate Heart after Partial-body Radiation with Minimal Bone Marrow Sparing

ABSTRACT

High-dose radiation exposure results in hematopoietic and gastrointestinal acute radiation syndromes followed by delayed effects of acute radiation exposure, which encompasses multiple organs, including heart, kidney, and lung. Here we sought to further characterize the natural history of radiation-induced heart injury via determination of differential protein and metabolite expression in the heart. We quantitatively profiled the proteome and metabolome of left and right ventricle from non-human primates following 12 Gy partial body irradiation with 2.5% bone marrow sparing over a time period of 3 wk. Global proteome profiling identified more than 2,200 unique proteins, with 220 and 286 in the left and right ventricles, respectively, showing significant responses across at least three time points compared to baseline levels. High-throughput targeted metabolomics analyzed a total of 229 metabolites and metabolite combinations, with 18 and 22 in the left and right ventricles, respectively, showing significant responses compared to baseline levels. Bioinformatic analysis performed on metabolomic and proteomic data revealed pathways related to inflammation, energy metabolism, and myocardial remodeling were dysregulated. Additionally, we observed dysregulation of the retinoid homeostasis pathway, including significant post-radiation decreases in retinoic acid, an active metabolite of vitamin A. Significant differences between left and right ventricles in the pathology of radiation-induced injury were identified. This multi-omic study characterizes the natural history and molecular mechanisms of radiation-induced heart injury in NHP exposed to PBI with minimal bone marrow sparing.

Outcomes of pericardiectomy for constrictive pericarditis following mediastinal irradiation

BACKGROUND

Pericardiectomy for postradiation constrictive pericarditis has been reported to generally have unfavorable outcomes. This study sought to evaluate surgical outcomes in a large cohort of patients undergoing pericardiectomy for radiation-associated pericardial constriction.

METHODS

A retrospective analysis of all patients (≥18 years) who underwent pericardiectomy for a diagnosis of constrictive pericarditis with a prior history of mediastinal irradiation from June 2002 to June 2019 was conducted. There were 100 patients (mean age 57.2 ± 10.1 years, 49% females) who met the inclusion criteria. Records were reviewed to look at the surgical approach, the extent of resection, early mortality, and late survival.

RESULTS

The overall operative mortality was 10.1% (n = 10). The rate of operative mortality decreased over the study period; however, the test of the trend was not statistically significant (p = .062). Hodgkin's disease was the most common malignancy (64%) for which mediastinal radiation had been received. Only 27% of patients had an isolated pericardiectomy, and concomitant pericardiectomy and valve surgery were performed in 46% of patients. Radical resection was performed in 50% of patients, whereas 47% of patients underwent subtotal resection. Prolonged ventilation (26%), atrial fibrillation (21%), and pleural effusion (16%) were the most common postoperative complications. The overall 1, 5-, and 10-years survival was 73.6%, 53.4%, and 32.1%, respectively. Increasing age (hazard ratio, 1.044, 95% confidence interval 1.017-1.073) appeared to have a significant negative effect on overall survival in the univariate model.

CONCLUSION

Pericardiectomy performed for radiation-associated constrictive pericarditis has poor long-term outcomes. The early mortality, though high (~10%), has been showing a decreasing trend in the test of time.

Redox interactions-induced cardiac toxicity in cancer therapy

Cancer patients undergoing radiotherapy, chemotherapy, or targeted cancer therapy are exposed to the risk of several side effects because of the heavy production of ROS by ionizing radiation or some chemotherapy drugs. Damages to DNA, mitochondria, membrane and other organelles within normal tissue cells such as cardiomyocytes and endothelial cells lead to the release of some toxins which are associated with triggering inflammatory cells to release several types of cytokines, chemokines, ROS, and RNS. The release of some molecules following radiotherapy or chemotherapy stimulates reduction/oxidation (redox) reactions. Redox reactions cause remarkable changes in the level of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Excessive production of ROS and RNS or suppression of antioxidant defense enzymes leads to damage to critical macromolecules, which may continue for long times. Increased levels of some cytokines and oxidative injury are hallmarks of heart injury following cancer therapy. Redox reactions may be involved in several heart disorders such as fibrosis, cardiomyopathy, and endothelium injury. In the current review, we explain the cellular and molecular mechanisms of redox interactions following radiotherapy, chemotherapy, and targeted cancer therapy. Afterward, we explain the evidence of the involvement of redox reactions in heart diseases.

Review of Deep Learning Based Automatic Segmentation for Lung Cancer Radiotherapy

Lung cancer is the leading cause of cancer-related mortality for males and females. Radiation therapy (RT) is one of the primary treatment modalities for lung cancer. While delivering the prescribed dose to tumor targets, it is essential to spare the tissues near the targets-the so-called organs-at-risk (OARs). An optimal RT planning benefits from the accurate segmentation of the gross tumor volume and surrounding OARs. Manual segmentation is a time-consuming and tedious task for radiation oncologists. Therefore, it is crucial to develop automatic image segmentation to relieve radiation oncologists of the tedious contouring work. Currently, the atlas-based automatic segmentation technique is commonly used in clinical routines. However, this technique depends heavily on the similarity between the atlas and the image segmented. With significant advances made in computer vision, deep learning as a part of artificial intelligence attracts increasing attention in medical image automatic segmentation. In this article, we reviewed deep learning based automatic segmentation techniques related to lung cancer and compared them with the atlas-based automatic segmentation technique. At present, the auto-segmentation of OARs with relatively large volume such as lung and heart etc. outperforms the organs with small volume such as esophagus. The average Dice similarity coefficient (DSC) of lung, heart and liver are over 0.9, and the best DSC of spinal cord reaches 0.9. However, the DSC of esophagus ranges between 0.71 and 0.87 with a ragged performance. In terms of the gross tumor volume, the average DSC is below 0.8. Although deep learning based automatic segmentation techniques indicate significant superiority in many aspects compared to manual segmentation, various issues still need to be solved. We discussed the potential issues in deep learning based automatic segmentation including low contrast, dataset size, consensus guidelines, and network design. Clinical limitations and future research directions of deep learning based automatic segmentation were discussed as well.

Monitoring of Metabolic Syndrome and Cardiovascular Disease in Childhood Cancer Survivors

Advances in cancer treatment have significantly improved childhood cancer survival, although metabolic syndrome and cardiovascular disease are common long-term complications that may occur years after treatment. Childhood cancer survivors may not receive appropriate follow-up due to lack of communication between oncologists and primary care physicians, or, from lack of awareness of possible long-term metabolic and cardiovascular complications after cancer treatment. We, therefore, reviewed current evidence on long-term effects of cancer therapy, and appropriate monitoring for long-term treatment effects in childhood cancer survivors that could lead to early detection and prompt treatment to prevent future cardiovascular events.

X‑irradiation induces acute and early term inflammatory responses in atherosclerosis‑prone ApoE‑/‑ mice and in endothelial cells

Thoracic radiotherapy is an effective treatment for many types of cancer; however it is also associated with an increased risk of developing cardiovascular disease (CVD), appearing mainly ≥10 years after radiation exposure. The present study investigated acute and early term physiological and molecular changes in the cardiovascular system after ionizing radiation exposure. Female and male ApoE^‑/‑ mice received a single exposure of low or high dose X‑ray thoracic irradiation (0.1 and 10 Gy). The level of cholesterol and triglycerides, as well as a large panel of inflammatory markers, were analyzed in serum samples obtained at 24 h and 1 month after irradiation. The secretion of inflammatory markers was further verified in vitro in coronary artery and microvascular endothelial cell lines after exposure to low and high dose of ionizing radiation (0.1 and 5 Gy). Local thoracic irradiation of ApoE^‑/‑ mice increased serum growth differentiation factor‑15 (GDF‑15) and C‑X‑C motif chemokine ligand 10 (CXCL10) levels in both female and male mice 24 h after high dose irradiation, which were also secreted from coronary artery and microvascular endothelial cells in vitro. Sex‑specific responses were observed for triglyceride and cholesterol levels, and some of the assessed inflammatory markers as detailed below. Male ApoE^‑/‑ mice demonstrated elevated intercellular adhesion molecule‑1 and P‑selectin at 24 h, and adiponectin and plasminogen activator inhibitor‑1 at 1 month after irradiation, while female ApoE^‑/‑ mice exhibited decreased monocyte chemoattractant protein‑1 and urokinase‑type plasminogen activator receptor at 24 h, and basic fibroblast growth factor 1 month after irradiation. The inflammatory responses were mainly significant following high dose irradiation, but certain markers showed significant changes after low dose exposure. The present study revealed that acute/early inflammatory responses occurred after low and high dose thoracic irradiation. However, further research is required to elucidate early asymptomatic changes in the cardiovascular system post thoracic X‑irradiation and to investigate whether GDF‑15 and CXCL10 could be considered as potential biomarkers for the early detection of CVD risk in thoracic radiotherapy‑treated patients.

Radiation-Induced Vascular Disease-A State-of-the-Art Review

Since the 1990s, there has been a steady increase in the number of cancer survivors to an estimated 17 million in 2019 in the US alone. Radiation therapy today is applied to a variety of malignancies and over 50% of cancer patients. The effects of ionizing radiation on cardiac structure and function, so-called radiation-induced heart disease (RIHD), have been extensively studied. We review the available published data on the mechanisms and manifestations of RIHD, with a focus on vascular disease, as well as proposed strategies for its prevention, screening, diagnosis, and management.

Trifascicular Block and Ventricular Standstill: A Late Complication of Mediastinal Radiotherapy in a Cancer Survivor

Over the last half-century, radiation therapy has evolved to become one of the cornerstones of treatment for various types of cancers. It is estimated that more than 50% of patients with cancer are treated with radiotherapy. Patients with early stages of some cancers can even achieve a cure with radiotherapy alone. Radiation-induced heart disease is a well-recognized cause of mortality and morbidity in cancer survivors as a late complication of radiotherapy, often occurring more than a decade after radiotherapy. We describe a case of a middle-aged female who presented to the hospital with syncopal episodes. She was in remission from non-Hodgkin's lymphoma having received mediastinal radiotherapy 20 years, previously. Her initial workup such as laboratory investigations and 12 lead electrocardiogram were largely unremarkable. Cardiac monitoring over the course of the next few days was consistent with complete heart block with evidence of ventricular standstill. Her symptoms resolved following the implantation of a dual-chamber cardiac pacemaker. This case highlights the significance of clinical history taking and putting together all relevant facts to come to a differential diagnosis. In our case, this could have been easily overlooked as radiation therapy was given many years previously. We review and present an up-to-date albeit brief literature review on long-term cardiovascular complications of radiotherapy. Radiation-induced cardiac complications are an important cause of mortality and morbidity in cancer survivors. This article aims to raise awareness amongst clinicians of cardiac adverse effects occurring several years after the radiation therapy. This case also highlights the need for further research to better understand the pathophysiology of cardiovascular disease post-radiotherapy in order to develop effective prevention strategies and improve clinical outcomes.

Focus on stereotactic radiotherapy: A new way to treat severe ventricular arrhythmias?

Ventricular tachycardia has a significant recurrence rate after ablation for several reasons, including inaccessible substrate. A non-invasive technique to ablate any defined areas of myocardium involved in arrhythmogenesis would be a potentially important therapeutic improvement if shown to be safe and effective. Early feasibility studies of single-fraction stereotactic body radiotherapy have demonstrated encouraging results, but rigorous evaluation and follow-up are required. In this document, the basic concepts of stereotactic body radiotherapy are summarized, before focusing on stereotactic arrhythmia radioablation. We describe the effect of radioablation on cardiac tissue and its interaction with intracardiac devices, depending on the dose. The different clinical studies on ventricular tachycardia radioablation are analysed, with a focus on target identification, which is the key feature of this approach. Our document ends with the indications and requirements for practicing this type of procedure in 2020. Finally, because of the limited number of patients treated so far, we encourage multicentre registries with long-term follow-up.

Does Internal Mammary Node Irradiation for Breast Cancer Make a Significant Difference to the Diameter of the Internal Mammary Artery? Correlation with Computed Tomography

Objective

Lymphatic irradiation in breast cancer improves locoregional control and has been shown to decrease distant metastasis. However, irradiation also accelerates the formation of atherosclerosis and can cause stenosis, not only in the coronary arteries but also in the internal mammary artery (IMA). The aim of this study was to investigate the effects of radiation on IMAs via computed tomography (CT).

Methods

We reviewed the data of 3,612 patients with breast cancer treated with radiotherapy (RT) between January 2010 and December 2016. We included 239 patients with appropriate imaging and nodal irradiation in the study. All patients were treated with lymphatic irradiation of 46-50 Gy, and a boost dose (6-10 Gy) to the involved internal mammary nodes (IMNs) when imaging studies demonstrated pathological enlargement. Bilateral IMA diameter and the presence of calcification were assessed via thin contrast-enhanced CT and those of ipsilateral irradiated IMAs were compared with those of contralateral nonirradiated IMAs.

Results

The mean diameter of irradiated IMAs was significantly shorter than that of nonirradiated IMAs, regardless of laterality. All vascular calcifications were determined on the irradiated side. A boost dose of radiation to the IMNs and radiation technique did not significantly affect the IMA diameter or the presence of calcification.

Conclusions

The diameter of the IMA is decreased due to RT regardless of laterality, radiation technique, and administration of a boost dose. Evaluation of vessels on CT before coronary artery bypass graft or flap reconstruction can help the surgeon select the most appropriate vessel.

The role of connexin proteins and their channels in radiation-induced atherosclerosis

Radiotherapy is an effective treatment for breast cancer and other thoracic tumors. However, while high-energy radiotherapy treatment successfully kills cancer cells, radiation exposure of the heart and large arteries cannot always be avoided, resulting in secondary cardiovascular disease in cancer survivors. Radiation-induced changes in the cardiac vasculature may thereby lead to coronary artery atherosclerosis, which is a major cardiovascular complication nowadays in thoracic radiotherapy-treated patients. The underlying biological and molecular mechanisms of radiation-induced atherosclerosis are complex and still not fully understood, resulting in potentially improper radiation protection. Ionizing radiation (IR) exposure may damage the vascular endothelium by inducing DNA damage, oxidative stress, premature cellular senescence, cell death and inflammation, which act to promote the atherosclerotic process. Intercellular communication mediated by connexin (Cx)-based gap junctions and hemichannels may modulate IR-induced responses and thereby the atherosclerotic process. However, the role of endothelial Cxs and their channels in atherosclerotic development after IR exposure is still poorly defined. A better understanding of the underlying biological pathways involved in secondary cardiovascular toxicity after radiotherapy would facilitate the development of effective strategies that prevent or mitigate these adverse effects. Here, we review the possible roles of intercellular Cx driven signaling and communication in radiation-induced atherosclerosis.

RADIOTHERAPY-ASSOCIATED CARDIOVASCULAR COMPLICATIONS IN CANCER (review)

The review is devoted to the current issues of radiation-induced cardiovascular complications, their diagnostics andincidence depending on the radiation doses and exposure regimens, potential efficiency of the screening strategiesfor cardiotoxicity monitoring after radiotherapy in cancer patients by analyzing the data from literature and clinical trials, based on recommendations of European Society of Cardiology and European Society of Medical Oncology.

Results of surgical resection of carotid body tumors: A twenty-year experience

This study examines whether surgical resection of carotid body tumors (CBTs) is acceptable in light of potential significant neurologic complications. This IRB-approved retrospective study analyzed data from 24 patients undergoing surgical treatment for CBTs between April 1998 and April 2017 at Mayo Clinic (Florida campus only). For patients who underwent multiple CBT resections, only data from the first surgery was used in this analysis. CBT resection occurred in 24 patients with the following demographics: fourteen patients (58.3%) were female, median age was 56.5 years, median BMI was 29. A prior history of neoplasm was found in ten patients (41.7%). A known family history of paraganglioma was present in five patients (20.8%). Two patients were positive for succinate dehydrogenase mutation (8.3%). Multiple paragangliomas were present in seven patients (29.2%). There was nerve sacrifice in three patients (12.5%) during resection. Carotid artery reconstruction and patch angioplasty occurred in one patient (4.2%). Complete resection occurred in 24 patients (100.0%). Postoperatively, one patient (4.2%) suffered stroke. No mortalities occurred within or beyond 30 days of surgery. Persistent cranial nerve injury occurred in two patients (8.3%) with vocal cord paralysis. There was no recurrence of CBT through last follow-up. Five patients (20.8%) were diagnosed with other neoplasms after resection, including basal cell carcinoma, contralateral carotid body tumor, glomus vagale, and glomus jugulare. There was 100% survival at 1 year in patients followed for that time (n = 17). Surgical treatment remains the first-line curative treatment to relieve symptoms and ensure non-recurrence. While acceptable, neurologic complications are significant and therefore detailed preoperative informed consent is mandatory.

Analyzing non-cancer causes of death of colorectal carcinoma patients in the US population for the years 2000-2016

Background

Colorectal cancer (CRC) treatment and patient survival improved greatly. Consequently an increased incidence of non‐cancer‐related deaths is observed. This study analyzed the causes of non‐cancer death for people suffering from CRC based on the year of diagnosis, follow‐up time, and patient's age.

Methods

The data from patients diagnosed with CRC in the years 2000–2016 were taken from the Surveillance, Epidemiology, and End Results 18 database. Patients were categorized according to: death from CRC, non‐CRC cancer, and non‐cancer. Constituent ratios and standardized mortality ratios (SMRs) were calculated to describe the death causes distribution and relative death risks.

Results

Between 2000 and 2016, a stable and rapid drop for the original diagnosis as death cause for CRC patients was observed (70.19% to 49.35%). This was coupled to an increase in non‐cancer‐associated death reasons (23.38% to 40.00%). The most common non‐cancer death cause was heart disease, especially for elderly patients. However, deaths from accidents and adverse effects were frequent in younger CRC patients. Patients died from septicemia more often within the first follow‐up year; however, a 6‐fold increase in death from Alzheimer's disease was found for after at least 180 months follow‐up time.

The SMRs of all 25 non‐cancer death causes initially decreased in all CRC subgroups, followed by an increase with follow‐up times. Gradually decreasing SMR values were observed with increasing age of CRC patients.

Conclusions

These findings could help modify and sharpen preventive measures and clinical management and raise physician's awareness to potential non‐CRC death risk factors for CRC patients.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of lymphoma

The recent development and clinical implementation of novel immunotherapies for the treatment of Hodgkin and non-Hodgkin lymphoma have improved patient outcomes across subgroups. The rapid introduction of immunotherapeutic agents into the clinic, however, has presented significant questions regarding optimal treatment scheduling around existing chemotherapy/radiation options, as well as a need for improved understanding of how to properly manage patients and recognize toxicities. To address these challenges, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts in lymphoma to develop a clinical practice guideline for the education of healthcare professionals on various aspects of immunotherapeutic treatment. The panel discussed subjects including treatment scheduling, immune-related adverse events (irAEs), and the integration of immunotherapy and stem cell transplant to form recommendations to guide healthcare professionals treating patients with lymphoma.

Transcatheter Versus Surgical Aortic Valve Replacement in Patients With Prior Mediastinal Radiation

OBJECTIVES

This study sought to evaluate the trends and outcomes of transcatheter aortic valve replacement (TAVR) versus surgical aortic valve replacement (SAVR) among patients with prior mediastinal radiation from a national database.

BACKGROUND

There is a paucity of data about the temporal trends and outcomes of TAVR versus SAVR in patients with prior mediastinal radiation.

METHODS

The National Inpatient Sample database years 2012 to 2017 was queried for hospitalizations of patients with prior mediastinal radiation who underwent isolated AVR. Using multivariable analysis, the study compared the outcomes of TAVR versus SAVR. The main study outcome was in-hospital mortality.

RESULTS

The final analysis included 3,675 hospitalizations for isolated AVR; of whom 2,170 (59.1%) underwent TAVR and 1,505 (40.9%) underwent isolated SAVR. TAVR was increasingly performed over time (p_trend = 0.01), but there was no significant increase in the rates of utilization of SAVR. The following factors were independently associated with TAVR utilization: older age, chronic lung disease, coronary artery disease, chronic kidney disease, prior cerebrovascular accidents, prior coronary artery bypass grafting, and larger-sized hospitals, while women were less likely to undergo TAVR. Compared with SAVR, TAVR was associated with lower in-hospital mortality (1.2% vs. 2.0%, adjusted odds ratio: 0.27; 95% confidence interval: 0.09 to 0.79; p = 0.02). TAVR was associated with lower rates of acute kidney injury, use of mechanical circulatory support, bleeding and respiratory complications, and shorter length of hospital stay. TAVR was associated with higher rates of pacemaker insertion.

CONCLUSIONS

This nationwide observational analysis showed that TAVR is increasingly performed among patients with prior mediastinal radiation. TAVR provides an important treatment option for this difficult patient population with desirable procedural safety when using SAVR as a benchmark.

Review of Stereotactic Arrhythmia Radioablation Therapy for Cardiac Tachydysrhythmias

Cardiac tachyarrhythmias are a major cause of morbidity and mortality. Treatments for these tachyarrhythmias include antiarrhythmic drugs, catheter ablation, surgical ablation, cardiac implantable electronic devices, and cardiac transplantation. Each of these treatment approaches is effective in some patients but there is considerable room for improvement, particularly with respect to the most common of the tachydysrhythmias, atrial fibrillation, and the most dangerous of the tachydysrhythmias, ventricular tachycardia (VT) or ventricular fibrillation. Noninvasive stereotactic ablative radiation therapy is emerging as an effective treatment for refractory tachyarrhythmias. Animal models have shown successful ablation of arrhythmogenic myocardial substrates with minimal short-term complications. Studies of stereotactic radioablation involving patients with refractory VT have shown a reduction in VT recurrence and promising early safety data. In this review, we provide the background for the application of stereotactic arrhythmia radioablation therapy along with promising results from early applications of the technology.

Modern Radiotherapy and Risk of Cardiotoxicity

Despite the advancements of modern radiotherapy, radiation-induced heart disease remains a common cause of morbidity and mortality amongst cancer survivors. This review outlines the basic mechanism, clinical presentation, risk stratification, early detection, possible mitigation, and treatment of this condition.

A pilot study of 13N-ammonia cardiac PET imaging to assess subacute cardiotoxicity following adjuvant intensity-modulated radiotherapy for locally advanced breast cancer

OBJECTIVE

(1) Assess the feasibility of 13 N-ammonia cardiac PET (13 N-ammonia-PET) imaging in radiotherapy (RT) treatment position in locally-advanced breast cancer (LABC) patients. (2) Correlate pre-/post-RT changes in myocardial flow reserve (MFR) with the corresponding radiation heart dose.

METHODS

Ten left-sided LABC patients undergoing Volumetric Modulated-Arc-Therapy (VMAT) to chest wall and regional lymph nodes underwent a rest/stress 13 N-ammonia-PET at baseline and (median) 13 months post-RT. Changes in cardiac functions and coronary artery Ca2+ scoring between baseline and follow-up were correlated with average RT dose to the myocardium,3 coronary territories, and 17 myocardial segments.

RESULTS

Eight (of 10) patients successfully completed the study. The average rest (stress) global MBF (ml.g-1.min-1) for baseline (follow-up) were 0.83 ± 0.25 (2.4 ± 0.79) and 0.92 ± 0.30 (2.76 ± 0.71), respectively. Differences in MBF, heart rate, blood pressure, and rate-pressure product (RPP) between baseline and follow-up were insignificant (P > 0.1).Strong (R = 0.79; P < 0.01) and moderate (R = 0.53; P = 0.37) correlation existed between MBF _Rest and MBF _Stress, and RPP respectively. Four patients showed a reduction in MFR of up to ~41% in follow-up studies, increasing to ~52% in myocardial segments close to high-radiation isodose lines in 5/8 patients. Agatston Ca + 2 scoring were zero in both baseline and follow-up in six patients; two patients exhibited mild increase in Ca + 2 on follow-ups (range:10-20).Rest and stress LVEF's were normal (>50) for all patients in both studies.

CONCLUSION

The feasibility of 13 N-ammonia-PET imaging in treatment position of LABC patients was demonstrated. MFR at 1-year post-irradiation of the heart decreased in 50% of the patients. MFR may be a potential index for early detection of cardiotoxicity in BC patients receiving RT to the chest wall.

Combination of Scalp Acupuncture with Exercise Therapy Effectively Counteracts Ischemic Brain Injury in Rats

BACKGROUND

Stroke is one of the leading causes of death and disability worldwide. Scalp acupuncture and exercise therapy have been proven as two effective methods for the treatment of stroke. However, their combined action and mechanisms have not been fully elucidated. The present study aimed to investigate the protective effect of scalp acupuncture combined with exercise therapy on neurons in rats with ischemic brain injury.

METHODS

100 rats were randomly divided into 5 groups including sham group, model group, acupuncture group, rehabilitation group, and experimental group (scalp acupuncture combined with exercise therapy). Middle cerebral artery occlusion (MCAO) model in rats was established according to Longa modified suture method to mimic ischemic stroke. The modified Bedexer's neurological function score was used to evaluate the neurological deficits of rats and the brain infarct volume was measured using 2, 3, 5-triphenyl tetrazolium chloride monohydrate (TTC) staining. Moreover, the apoptosis in the hippocampus was detected by western blotting and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The pro-inflammatory cytokines such as interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α), reactive oxygen species (ROS) and superoxide dismutase (SOD) were determined by corresponding kits. Immunohistochemistry or immunofluorescence was performed to detect the expression of brain-derived neurotrophic factor (BDNF), S100β and glial fibrillary acidic protein (GFAP) in the hippocampi of rats.

RESULTS

The neurological deficit score, the expression levels of apoptotic factors such as cleaved caspase-3 and Bax, and the TUNEL-positive cell rate of the experimental group were significantly lower than those of the acupuncture group and the rehabilitation group. However, apoptosis inhibitor Bcl-2 showed downregulated expression in the MCAO model rats but this trend was reverted by single and combinatorial treatments. In addition, the contents of TNF-α, IL-1β and ROS in the acupuncture group and the rehabilitation group were significantly lower than those in the model group, but higher than the experimental group. While the opposite results were obtained in SOD activity. Furthermore, compared with the model group, the ratios of BDNF, S100β, and GFAP-positive cells in the acupuncture, rehabilitation and experimental groups were significantly increased, and the highest ratios were recorded in the experimental group.

CONCLUSIONS

This study demonstrated that scalp acupuncture combined with exercise therapy effectively counteracts ischemic brain injury via the downregulation of pro-inflammatory mediators and ROS, the increased production of the antioxidant enzyme SOD, neurotrophic factor BDNF and astrocyte activities.

The effect of chronic low-dose environmental radiation on organ mass of bank voles in the Chernobyl exclusion zone

PURPOSE

Animals are exposed to environmental ionizing radiation (IR) externally through proximity to contaminated soil and internally through ingestion and inhalation of radionuclides. Internal organs can respond to radioactive contamination through physiological stress. Chronic stress can compromise the size of physiologically active organs, but studies on wild mammal populations are scarce. The effects of environmental IR contamination on organ masses were studied by using a wild rodent inhabiting the Chernobyl exclusion zone (CEZ).

MATERIAL AND METHODS

The masses of brain, heart, kidney, spleen, liver and lung were assessed from bank voles (Myodes glareolus) captured from areas across radioactive contamination gradient within the CEZ. Relative organ masses were used to correct for the body mass of an individual.

RESULTS

Results showed a significant negative correlation between IR level in the environment and relative brain and kidney mass. A significant positive correlation between IR and relative heart mass was also found. Principal component analysis (PCA) also suggested positive relationship between IR and relative spleen mass; however, this relationship was not significant when spleen was analyzed separately. There was no apparent relationship between IR and relative liver or lung mass.

CONCLUSIONS

Results suggest that in the wild populations even low but chronic doses of IR can lead to changes in relative organ mass. The novelty of these result is showing that exposure to low doses can affect the organ masses in similar fashion as previously shown on high, acute, radiation doses. These data support the hypothesis that wildlife might be more sensitive to IR than animals used in laboratory studies. However, more research is needed to rule out the other indirect effects such as radiosensitivity of the food sources or possible combined stress effects from e.g. infections.

Radiation-induced myocardial fibrosis: Mechanisms underlying its pathogenesis and therapeutic strategies

Radiation-induced myocardial fibrosis (RIMF) is a potentially lethal clinical complication of chest radiotherapy (RT) and a final stage of radiation-induced heart disease (RIHD). RIMF is characterized by decreased ventricular elasticity and distensibility, which can result in decreased ejection fraction, heart failure and even sudden cardiac death. Together, these conditions impair the long-term health of post-RT survivors and limit the dose and intensity of RT required to effectively kill tumour cells. Although the exact mechanisms involving in RIMF are unclear, increasing evidence indicates that the occurrence of RIMF is related to various cells, regulatory molecules and cytokines. However, accurately diagnosing and identifying patients who may progress to RIMF has been challenging. Despite the urgent need for an effective treatment, there is currently no medical therapy for RIMF approved for routine clinical application. In this review, we investigated the underlying pathophysiology involved in the initiation and progression of RIMF before outlining potential preventative and therapeutic strategies to counter this toxicity.

Statin Intolerance, Anti-HMGCR Antibodies, and Immune Checkpoint Inhibitor-Associated Myositis: A "Two-Hit" Autoimmune Toxicity or Clinical Predisposition?

Immune-related adverse events induced by immune checkpoint inhibitor (ICI) therapy may affect diverse organ systems, including skeletal and cardiac muscle. ICI-associated myositis may result in substantial morbidity and occasional mortality. We present a case of a patient with advanced non-small cell lung cancer who developed grade 4 myositis with concurrent myocarditis early after initiation of anti-programmed death ligand 1 therapy (durvalumab). Autoantibody analysis revealed marked increases in anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody levels that preceded clinical toxicity, and further increased during toxicity. Notably, the patient had a history of intolerable statin myopathy, which had resolved clinically after statin discontinuation and prior to ICI initiation. This case demonstrates a potential association between statin exposure, autoantibodies, and ICI-associated myositis.

Simulated spatial radiation impacts learning and memory ability with alterations of neuromorphology and gut microbiota in mice

Complex space environments, including microgravity and radiation, affect the body's central nervous system, endocrine system, circulatory system, and reproductive system. Radiation-induced aberration in the neuronal integrity and cognitive functions are particularly well known. Moreover, ionizing radiation is a likely contributor to alterations in the microbiome. However, there is a lacuna between radiation-induced memory impairment and gut microbiota. The present study was aimed at investigating the effects of simulated space-type radiation on learning and memory ability and gut microbiota in mice. Adult mice were irradiated by 60Co-γ rays at 4 Gy to simulate spatial radiation; behavioral experiments, pathological experiments, and transmission electron microscopy all showed that radiation impaired learning and memory ability and hippocampal neurons in mice, which was similar to the cognitive impairment in neurodegenerative diseases. In addition, we observed that radiation destroyed the colonic structure of mice, decreased the expression of tight junction proteins, and increased inflammation levels, which might lead to dysregulation of the intestinal microbiota. We found a correlation between the brain and colon in the changes in neurotransmitters associated with learning and memory. The 16S rRNA results showed that the bacteria associated with these neurotransmitters were also changed at the genus level and were significantly correlated. These results indicate that radiation-induced memory and cognitive impairment can be linked to gut microbiota through neurotransmitters.

Recognizing Radiation Therapy-related Complications in the Chest

Radiation therapy is one of the cornerstones for the treatment of thoracic malignancies. Although advances in radiation therapy technology have improved the delivery of radiation considerably, adverse effects are still common. Postirradiation changes affect the organ or tissue treated and the neighboring structures. Advances in external-beam radiation delivery techniques and how these techniques affect the expected thoracic radiation-induced changes are described. In addition, how to distinguish these expected changes from complications such as infection and radiation-induced malignancy, and identify treatment failure, that is, local tumor recurrence, is reviewed. ^©RSNA, 2019.

Radiation-Induced Left Main Coronary Artery Stenosis in a Patient with Atretic Internal Mammary Arteries

Coronary artery disease (CAD) is a known potential complication of thoracic radiation treatment that typically affects the proximal segments of the coronary arteries, requiring coronary artery bypass grafting (CABG). We present a case of acute coronary syndrome occurring in a 57-year-old man with prior thoracic radiation therapy following resection of a chest wall chondrosarcoma. Coronary angiogram demonstrated significant areas of stenosis in the left main coronary artery (LMCA) and ostial left anterior descending (LAD) coronary artery. The patient was also found to have atretic bilateral internal mammary arteries as a consequence of his radiation therapy, rendering them unsuitable as grafts. Percutaneous coronary intervention (PCI) was thus performed with a successful outcome. To our knowledge, this is the first case of radiation-induced CAD of the LMCA with atretic internal mammary arteries treated successfully with PCI.

Connexin43 Hemichannel Targeting With TAT-Gap19 Alleviates Radiation-Induced Endothelial Cell Damage

BACKGROUND

Emerging evidence indicates an excess risk of late occurring cardiovascular diseases, especially atherosclerosis, after thoracic cancer radiotherapy. Ionizing radiation (IR) induces cellular effects which may induce endothelial cell dysfunction, an early marker for atherosclerosis. In addition, intercellular communication through channels composed of transmembrane connexin proteins (Cxs), i.e. Gap junctions (direct cell-cell coupling) and hemichannels (paracrine release/uptake pathway) can modulate radiation-induced responses and therefore the atherosclerotic process. However, the role of endothelial hemichannel in IR-induced atherosclerosis has never been described before.

MATERIALS AND METHODS

Telomerase-immortalized human Coronary Artery/Microvascular Endothelial cells (TICAE/TIME) were exposed to X-rays (0.1 and 5 Gy). Production of reactive oxygen species (ROS), DNA damage, cell death, inflammatory responses, and senescence were assessed with or without applying a Cx43 hemichannel blocker (TAT-Gap19).

RESULTS

We report here that IR induces an increase in oxidative stress, cell death, inflammatory responses (IL-8, IL-1β, VCAM-1, MCP-1, and Endothelin-1) and premature cellular senescence in TICAE and TIME cells. These effects are significantly reduced in the presence of the Cx43 hemichannel-targeting peptide TAT-Gap19.

CONCLUSION

Our findings suggest that endothelial Cx43 hemichannels contribute to various IR-induced processes, such as ROS, cell death, inflammation, and senescence, resulting in an increase in endothelial cell damage, which could be protected by blocking these hemichannels. Thus, targeting Cx43 hemichannels may potentially exert radioprotective effects.

Oxidative Stress in Radiation-Induced Cardiotoxicity

There is a distinct increase in the risk of heart disease in people exposed to ionizing radiation (IR). Radiation-induced heart disease (RIHD) is one of the adverse side effects when people are exposed to ionizing radiation. IR may come from various forms, such as diagnostic imaging, radiotherapy for cancer treatment, nuclear disasters, and accidents. However, RIHD was mainly observed after radiotherapy for chest malignant tumors, especially left breast cancer. Radiation therapy (RT) has become one of the main ways to treat all kinds of cancer, which is used to reduce the recurrence of cancer and improve the survival rate of patients. The potential cause of radiation-induced cardiotoxicity is unclear, but it may be relevant to oxidative stress. Oxidative stress, an accumulation of reactive oxygen species (ROS), disrupts intracellular homeostasis through chemical modification and damages proteins, lipids, and DNA; therefore, it results in a series of related pathophysiological changes. The purpose of this review was to summarise the studies of oxidative stress in radiotherapy-induced cardiotoxicity and provide prevention and treatment methods to reduce cardiac damage.

Cardiac substructure segmentation with deep learning for improved cardiac sparing

PURPOSE

Radiation dose to cardiac substructures is related to radiation-induced heart disease. However, substructures are not considered in radiation therapy planning (RTP) due to poor visualization on CT. Therefore, we developed a novel deep learning (DL) pipeline leveraging MRI's soft tissue contrast coupled with CT for state-of-the-art cardiac substructure segmentation requiring a single, non-contrast CT input.

MATERIALS/METHODS

Thirty-two left-sided whole-breast cancer patients underwent cardiac T2 MRI and CT-simulation. A rigid cardiac-confined MR/CT registration enabled ground truth delineations of 12 substructures (chambers, great vessels (GVs), coronary arteries (CAs), etc.). Paired MRI/CT data (25 patients) were placed into separate image channels to train a three-dimensional (3D) neural network using the entire 3D image. Deep supervision and a Dice-weighted multi-class loss function were applied. Results were assessed pre/post augmentation and post-processing (3D conditional random field (CRF)). Results for 11 test CTs (seven unique patients) were compared to ground truth and a multi-atlas method (MA) via Dice similarity coefficient (DSC), mean distance to agreement (MDA), and Wilcoxon signed-ranks tests. Three physicians evaluated clinical acceptance via consensus scoring (5-point scale).

RESULTS

The model stabilized in ~19 h (200 epochs, training error <0.001). Augmentation and CRF increased DSC 5.0 ± 7.9% and 1.2 ± 2.5%, across substructures, respectively. DL provided accurate segmentations for chambers (DSC = 0.88 ± 0.03), GVs (DSC = 0.85 ± 0.03), and pulmonary veins (DSC = 0.77 ± 0.04). Combined DSC for CAs was 0.50 ± 0.14. MDA across substructures was <2.0 mm (GV MDA = 1.24 ± 0.31 mm). No substructures had statistical volume differences (P > 0.05) to ground truth. In four cases, DL yielded left main CA contours, whereas MA segmentation failed, and provided improved consensus scores in 44/60 comparisons to MA. DL provided clinically acceptable segmentations for all graded patients for 3/4 chambers. DL contour generation took ~14 s per patient.

CONCLUSIONS

These promising results suggest DL poses major efficiency and accuracy gains for cardiac substructure segmentation offering high potential for rapid implementation into RTP for improved cardiac sparing.