Radiation-related heart disease: current knowledge and future prospects

Assessing the level of radiation experienced by anesthesiologists during transfemoral Transcatheter Aortic Valve Implantation and protection by a lead cap

OBJECTIVE

Transfemoral Transcatheter Aortic Valve Implantation (TAVI) has become a standard therapy for patients with aortic valve stenosis. Fluoroscopic imaging is essential for TAVI with the anesthesiologist's workplace close to patient's head side. While the use of lead-caps has been shown to be useful for interventional cardiologists, data are lacking for anesthesiologists.

METHODS

A protective cap with a 0.35 lead-equivalent was worn on 15 working days by one anesthesiologist. Six detectors (three outside, three inside) were analyzed to determine the reduction of radiation. Literature search was conducted between April and October 2018.

RESULTS

In the observational period, 32 TAVI procedures were conducted. A maximum radiation dose of 0.55 mSv was detected by the dosimeters at the outside of the cap. The dosimeters inside the cap, in contrast, displayed a constant radiation dose of 0.08 mSv.

CONCLUSION

The anesthesiologist's head is exposed to significant radiation during TAVI and it can be protected by wearing a lead-cap.

Incidence of atrial fibrillation in conjunction with breast cancer

BACKGROUND

Patients with breast cancer may have an increased incidence of atrial fibrillation (AF) because of the systemic inflammation induced by the cancer and side effects of treatments.

OBJECTIVE

The purpose of this study was to estimate the long-term incidence of AF in patients with breast cancer compared with the background population.

METHODS

We identified patients diagnosed with breast cancer from 1998 to 2015 by using nationwide registries. Female patients with breast cancer were matched (1:3) by age and sex with the background population. The long-term incidence of AF was estimated by cumulative incidence curves and multivariable Cox regression models.

RESULTS

We matched 74,155 patients with breast cancer with 222,465 patients from the background population. Breast cancer was associated with incident AF and the association differed between age groups (interaction analysis, P < .0001) and follow-up time periods. In patients younger than 60 years breast cancer was associated with increased incidence of AF during the first 6 months (hazard ratio [HR] 2.10; 95% confidence interval [CI] 1.25-3.44) and from 6 months to 3 years (HR 1.80; 95% CI 1.38-2.35). In patients older than 60 years, breast cancer was not associated with increased incidence of AF during the first 6 months (HR 1.13; 95% CI 0.95-1.34) and was associated with increased incidence of AF from 6 months to 3 years (HR 1.14; 95% CI 1.05-1.25).

CONCLUSION

The long-term incidence of AF was increased in patients with breast cancer and short-term incidence was increased in patients younger than 60 years and similar in patients older than 60 years compared with the background population.

[Successful surgical treatment of aortic heart disease as a complication after combined targeted therapy for cancer]

Cardiovascular diseases and malignancies are leading causes of mortality in the world. Two categories of advanced age patients with cancer are observed in clinical practice. These are patients with cardiovascular diseases as comorbidities and patients with cardiovascular diseases as a complications of targeted therapy for cancer. Cardiac toxicity of chemotherapeutic drugs results myocardial dysfunction, occurrence or progression of heart valve disease, coronary artery disease, arterial hypertension and thromboembolism. A patient who underwent aortic valve replacement and coronary artery bypass surgery is discussed in the article. Aortic valve disease and coronary artery disease were complications of targeted radio- and chemotherapy for sigmoid colon cancer followed by lung and liver metastases. Questions of timely diagnosis and treatment of advanced age patients in multi-field surgical clinic are also analyzed.

A clinical prescription for heart health in midlife women

Cardiovascular disease is the leading cause of death in women throughout the United States and Europe. Despite efforts to raise awareness, the sex-specific risk factors are still poorly recognized in both regions, and many women do not identify cardiovascular disease as a primary threat. During midlife, the incidence of cardiovascular disease increases dramatically, and this unique time gives an opportunity to identify both traditional cardiovascular risk factors as well as emerging risk factors unique to women. This review will focus on the current guidelines for cardiovascular risk assessment in Europe and the United States, traditional and emerging cardiovascular risk factors, and preventive lifestyle recommendations for midlife women.

Automatic segmentation of cardiac substructures from noncontrast CT images: accurate enough for dosimetric analysis?

PURPOSE

We evaluated the feasibility of using an automatic segmentation tool to delineate cardiac substructures from noncontrast computed tomography (CT) images for cardiac dosimetry and toxicity analyses for patients with nonsmall cell lung cancer (NSCLC) after radiotherapy.

MATERIAL AND METHODS

We used an in-house developed multi-atlas segmentation tool to delineate 11cardiac substructures, including the whole heart, four heart chambers, and six greater vessels, automatically from the averaged 4D-CT planning images of 49 patients with NSCLC. Two experienced radiation oncologists edited the auto-segmented contours. Times for automatic segmentation and modification were recorded. The modified contours were compared with the auto-segmented contours in terms of Dice similarity coefficient (DSC) and mean surface distance (MSD) to evaluate the extent of modification. Differences in dose-volume histogram (DVH) characteristics were also evaluated for the modified versus auto-segmented contours.

RESULTS

The mean automatic segmentation time for all 11 structures was 7-9 min. For the 49 patients, the mean DSC values (±SD) ranged from .73 ± .08 to .95 ± .04, and the mean MSD values ranged from 1.3 ± .6 mm to 2.9 ± 5.1 mm. Overall, the modifications were small; the largest modifications were in the pulmonary vein and the inferior vena cava. The heart V30 (volume receiving dose ≥30 Gy) and the mean dose to the whole heart and the four heart chambers were not different for the modified versus the auto-segmented contours based on the statistically significant condition of p < .05. Also, the maximum dose to the great vessels was no different except for the pulmonary vein.

CONCLUSIONS

Automatic segmentation of cardiac substructures did not require substantial modifications. Dosimetric evaluation showed no significant difference between the auto-segmented and modified contours for most structures, which suggests that the auto-segmented contours can be used to study cardiac dose-responses in clinical practice.

Prognostic and Added Value of Echocardiographic Strain for Prediction of Adverse Outcomes in Patients with Locally Advanced Non-Small Cell Lung Cancer after Radiotherapy

Radiotherapy (RT) is potentially related to cardiotoxicity, which may partially offset the benefits of cancer treatment. We sought to evaluate subclinical myocardial dysfunction using speckle tracking echocardiography after RT and to explore the associations between early cardiac effects and adverse outcomes in patients with non-small cell lung cancer (NSCLC). In total, 112 patients with stage III NSCLC who were scheduled to receive RT were prospectively recruited. A reduction in global longitudinal strain (GLS) was observed immediately after RT and at 6 mo after RT (6 m-RT). In multivariable analysis, the percentage change in GLS from baseline to 6 mo (ΔGLS%_{6 m-RT}) (hazard ratio = 1.202, 95% confidence interval: 1.095-1.320, p < 0.001) was an independent predictor of all-cause mortality. Based on receiver operating characteristic curve analysis, ΔGLS%_{6 m-RT} ≥13.65% had 65.9% sensitivity and 85.2% specificity for predicting mortality in NSCLC patients (area under the curve = 0.784, 95% confidence interval: 0.692-0.876, p < 0.001). These findings should encourage physicians to perform echocardiography early after RT.

The role of irradiated heart and left ventricular volumes in heart failure occurrence after childhood cancer

BACKGROUND

Paediatric cancer survivors have a high risk of developing cardiac diseases, and the most frequent cardiac disease is heart failure (HF). The radiation dose-volume effects in the heart and cardiac substructures have not been explored in childhood cancer survivors (CCS). Therefore, the role of irradiated heart volume in the occurrence of HF among this population remains unclear. The aims of this study were to determine the doses and irradiated volumes of the heart and left ventricle (LV) related to the risk of HF in CCS and to investigate the impact of anthracycline exposure on this risk.

METHODS AND RESULTS

A case-control study nested in the French Childhood Cancer Survivors Study cohort. The mean heart and left ventricular doses and volumes indicators were estimated by reconstruction of individual treatments. A total of 239 HF cases and 1042 matched controls were included. The median age of HF diagnosis was 25.1 years. The median volume of the heart that received ≥ 30 Gy was 61.1% for cases and 16.9% for controls. In patients who did not receive anthracycline, the risk of HF was increased 3.6-fold when less than 10% of the LV received ≥ 30 Gy when compared to patients who were not exposed to any cardiac radiation and anthracycline.

CONCLUSIONS

Small irradiated volumes of the heart or LV were significantly associated with HF risk. To the author's knowledge, this is the first study to report a dose-response relationship based on dose-volume indicators in CCS, which can be translated efficiently into current clinical practice.

[18F]FDG cardiac PET imaging in a canine model of radiation-induced cardiovascular disease associated with breast cancer radiotherapy

Radiotherapy for the treatment of left-sided breast cancer increases the long-term risk of cardiovascular disease. The purpose of the present study was to noninvasively image the progression of radiation-induced cardiac inflammation in a large animal model using a hybrid PET and MRI system. Five canines were imaged using [¹⁸F]fluorodeoxyglucose PET to assess changes in myocardial inflammation. All animals were imaged at baseline, 1 wk, and 1, 3, 6, and 12 mo after focused cardiac external beam irradiation with image guidance. Radiation was delivered in a single fraction. The linear quadratic model was used to convert a typical multifractionated heart dose to a corrected single-fraction biologically equivalent dose. Immunohistochemistry was performed on excised left ventricular tissue samples from all five irradiated canines and one nonirradiated control canine to confirm the presence of inflammation. The mean doses delivered to the entire heart, left ventricle, left anterior descending artery, and left circumflex artery were 1.7 ± 0.2, 2.7 ± 0.2, 5.5 ± 0.9, and 1.1 ± 0.4 Gy, respectively. FDG standard uptake values remained persistently elevated compared with baseline (1.1 ± 0.03 vs. 2.6 ± 0.19, P < 0.05). The presence of myocardial inflammation was confirmed histologically and correlated with myocardial dose. This study suggests a global inflammatory response that is persistent up to 12 mo postirradiation. Inflammation PET imaging should be considered in future clinical studies to monitor the early changes in cardiac function that may play a role in the ultimate development of radiation-induced cardiac toxicity. NEW & NOTEWORTHY Using advanced cardiac PET imaging, we have shown the spatial and quantitative relationship between radiation dose deposition and temporal changes in inflammation. We have shown that the progression of radiation-induced cardiac inflammation is immediate and does not subside for up to 1 yr after radiation. Results are presented in a large animal model that closely resembles the size and vessel architecture of humans. The proposed imaging protocol can be easily replicated for clinical use.

Effects of a novel peptide Ac-SDKP in radiation-induced coronary endothelial damage and resting myocardial blood flow

BACKGROUND

Cancer survivors treated with thoracic ionizing radiation are at higher risk of premature death due to myocardial ischemia. No therapy is currently available to prevent or mitigate these effects. We tested the hypothesis that an endogenous tetrapeptide N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP) counteracts radiation-induced coronary vascular fibrosis and endothelial cell loss and preserves myocardial blood flow.

METHODS

We examined a rat model with external-beam-radiation exposure to the cardiac silhouette. We treated a subgroup of irradiated rats with subcutaneous Ac-SDKP for 18-weeks. We performed cardiac MRI with Gadolinium contrast to examine resting myocardial blood flow content. Upon sacrifice, we examined coronary endothelial-cell-density, fibrosis, apoptosis and endothelial tight-junction proteins (TJP). In vitro, we examined Ac-SDKP uptake by the endothelial cells and tested its effects on radiation-induced reactive oxygen species (ROS) generation. In vivo, we injected labeled Ac-SDKP intravenously and examined its endothelial localization after 4-h.

RESULTS

We found that radiation exposure led to reduced resting myocardial blood flow content. There was concomitant endothelial cell loss and coronary fibrosis. Smaller vessels and capillaries showed more severe changes than larger vessels. Real-time PCR and confocal microscopy showed radiation-induced loss of TJ proteins including-claudin-1 and junctional adhesion molecule-2 (JAM-2). Ac-SDKP normalized myocardial blood flow content, inhibited endothelial cell loss, reduced coronary fibrosis and restored TJ-assembly. In vitro, Ac-SDKP localized to endothelial cells and inhibited radiation-induced endothelial ROS generation. In vivo, labeled Ac-SDKP was visualized into the endothelium 4-h after the intravenous injection.

CONCLUSIONS

We concluded that Ac-SDKP has protective effects against radiation-induced reduction of myocardial blood flow. Such protective effects are likely mediated by neutralization of ROS-mediated injury, preservation of endothelial integrity and inhibition of fibrosis. This demonstrates a strong therapeutic potential of Ac-SDKP to counteract radiotherapy-induced coronary disease.

B-type natriuretic peptide plasma level in 5-year breast cancer survivors after radiotherapy

BACKGROUND

Left-sided breast cancer patients treated with radiotherapy (RT) are at risk for late radiation-induced cardiovascular complications.

AIM

The aim of this study was to investigate the BNP plasma levels in long-term breast cancer survivors who received only RT as well to assess whether cardiac dose was associated with BNP values.

METHODS

Plasma samples for BNP measurement were repeated in 29 patients (63 ± 11 years) who were alive at 5 years after radiotherapy, free of heart disease and available to provide new blood sample. All patients had BNP measurements at baseline. The ΔBNP was measured to analyze the role of marker variations. No patients received chemotherapy.

RESULTS

The mean cardiac and ventricle dose were 2.1 ± 1.0 (range 0.02-4.5) Gy and 3.0 ± 1.7 (range 0.02-7.6), respectively. Median value of BNP was 47 pg/mL (interquartile ranges, 26-58.2 pg/mL) at baseline, and 34 pg/mL (interquartile ranges, 17.5-54 pg/mL) at 5 years after radiotherapy. There was no significantly different between two measurements (p = ns). Fifteen (52%) reported an improvement in BNP levels, 1 (3%) no changes and 13 (45%) reported a worsening. There was no correlation between ΔBNP and age (p = ns). When patients were stratified according to the median value of dose-volume data, ΔBNP was significantly higher in patients with increased cardiac D_mean (p = .02) and left ventricle D_mean (p = .009).

CONCLUSION

At 5 years after radiotherapy, median plasma BNP levels remained within the normal range, but the delta-BNP levels are directly related to the heart and ventricular dose received.

Dosimetric comparison of advanced radiotherapy approaches using photon techniques and particle therapy in the postoperative management of thymoma

BACKGROUND

The purpose of this study was to compare dosimetric differences related to target volume and organs-at-risk (OAR) using 3D-conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), TomoTherapy (Tomo), proton radiotherapy (PRT), and carbon ion radiotherapy (CIRT) as part of postoperative thymoma irradiation.

MATERIAL AND METHODS

This single-institutional analysis included 10 consecutive patients treated with adjuvant radiotherapy between December 2013 and September 2016. CT-datasets and respective RT-structures were anonymized and plans for all investigated RT modalities (3DCRT, VMAT, Tomo, PRT, CIRT) were optimized for a total dose of 50 Gy in 25 fractions. Comparisons between target volume and OAR dosimetric parameters were performed using the Wilcoxon rank-sum test.

RESULTS

The best target volume coverage (mean PTV V_95% for all patients) was observed for Tomo (97.9%), PRT (97.6%), and CIRT (96.6%) followed by VMAT (85.4%) and 3DCRT (74.7%). PRT and CIRT both significantly reduced mean doses to the lungs, breasts, heart, and esophagus, as well as the spinal cord maximum dose compared with photon modalities. Among photon-based techniques, VMAT showed improved OAR sparing over 3DCRT. Tomo was associated with considerable low-dose exposure to the lungs, breasts, and heart.

CONCLUSIONS

Particle radiotherapy (PRT, CIRT) showed superior OAR sparing and optimal target volume coverage. The observed dosimetric advantages are expected to reduce toxicity rates. However, their clinical impact must be investigated prospectively.

EPIDEMIOLOGICAL STUDY OF HEALTH EFFECTS IN FUKUSHIMA NUCLEAR EMERGENCY WORKERS-STUDY DESIGN AND PROGRESS REPORT

Between 14 March and 16 December 2011, the radiation dose limit for emergency work was tentatively raised from an effective dose of 100-250 mSv by the Japanese Government after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. The objective of this study is to clarify the long-term health effects of radiation on the emergency workers involved during that period, based on a detailed evaluation of the radiation exposures and long-term monitoring. The potential subjects of the study are the approximately 20 000 workers who were engaged in emergency operations at FDNPP during the period described above. During the first phase of this project, the first 5 years from 2014, we plan to set up a research scheme and establish a cohort. To date, the establishment of the scheme for general health examinations is nearly complete. As of 31 January 2017, 5419 emergency workers (27.4% of the subjects) have agreed to participate in the study. We will continue our efforts to recruit additional potential subjects during the first phase to maximize the size of the cohort.

Quantification of cardiac subvolume dosimetry using a 17 segment model of the left ventricle in breast cancer patients receiving tangential beam radiotherapy

PURPOSE

Subacute changes following breast radiotherapy have been demonstrated in discrete areas of the left ventricle (LV), with recent guidelines being developed to help determine dose to subvolumes of the LV. This study aims to determine doses to the 17 segments of the LV as per the American Heart Association (AHA) and other cardiac subvolumes, and to correlate mean heart (MHD) dose with various subvolume dosimetric indices. These results may direct focus to specific left ventricular segments in studies of radiation-related heart disease incorporating surveillance imaging, help to determine more precise dose response relationships, and potentially aid prediction of late radiation effects.

METHODS AND MATERIALS

The heart and cardiac subvolumes of 29 patients treated with tangential radiotherapy for left breast cancer were contoured. Delineation of cardiac subvolumes (cardiac chambers, cardiac valves and the 17 segments of the LV) was undertaken using a novel contouring method on planning CT data reformatted into the cardiac axis. Individual segments were then combined to determine doses to the basal, mid and apical left ventricular regions, and the anterior, septal, inferior and lateral ventricular walls. Radiotherapy doses (including maximum, mean, D1cc, V25) were determined. Correlation analyses were performed between MHD and various substructure dosimetric indices.

RESULTS

Twenty five patients received tangential breast free breathing radiotherapy alone, and four patients received regional nodal irradiation including the internal mammary chain with deep inspiration breath hold (DIBH). For patients receiving breast only radiation, the median mean heart radiation dose was 2.62 Gy (range 1.52-3.90 Gy), and a heterogeneous dose distribution to the LV was noted, with the apical region receiving the highest median mean dose (14.99 Gy) compared with the mid and basal regions (3.10 Gy and 1.51 Gy respectively). The anterior LV wall received the highest median mean dose (9.21 Gy) with the remaining walls receiving similar mean doses (range 1.79-3.05 Gy). The anterior LV apical segment (segment 13) and apex (segment 17) received the highest individual median mean segment doses (26.73 Gy and 30.02 Gy respectively). Apical segments received the highest median mean doses (segments 13, 14, 15, 16), followed by the mid anterior (segment 7) and anteroseptal (segment 8) segments. Segments receiving the highest doses remained unchanged between the DIBH cohort and free breathing cohort. MHD showed a high correlation with the anterior wall r = 0.71, p < 0.05 and entire left ventricle r = 0.82, p < 0.05, but correlations varied from weak to high when MHD was correlated with segments receiving highest doses (range r = 0.43-0.76), p < 0.05.

CONCLUSIONS

In the setting of breast cancer radiotherapy, there are substantial RT dose variations within specific LV segments, with mid and apical anterior ventricular segments (segments 7, 13) and the apical region of the LV (segments 13, 14, 15, 16, 17) being consistently exposed to the highest radiation doses. Determining segmental and regional RT doses to the left ventricle may help guide focus in diagnostic cardiology in the post radiotherapy setting.

Doses of radiation to the pericardium, instead of heart, are significant for survival in patients with non-small cell lung cancer

BACKGROUND AND PURPOSE

Higher cardiac dose was associated with worse overall survival in the RTOG0617 study. Pericardial effusion (PCE) is a common cardiac complication of thoracic radiation therapy (RT). We investigated whether doses of radiation to the heart and pericardium are associated with PCE and overall survival in patients treated with thoracic radiation for non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

A total of 94 patients with medically inoperable/unresectable NSCLC treated with definitive RT in prospective studies were reviewed for this secondary analysis. Heart and pericardium were contoured consistently according to the RTOG1106 Atlas, with the great vessels and thymus of the upper mediastinal structures included in the upper part of pericardium, only heart chambers included in the heart structure. Clinical factors and dose-volume parameters associated with PCE or survival were identified via Cox proportional hazards modeling. The risk of PCE and death were mapped using DVH atlases.

RESULTS

Median follow-up for surviving patients was 58 months. The overall rate of PCE was 40.4%. On multivariable analysis, dosimetric factors of heart and pericardium were significantly associated with the risk of PCE. Pericardial V30 and V55 were significantly correlated with overall survival, but presence of PCE and heart dosimetric factors were not.

CONCLUSION

PCE was associated with both heart and pericardial doses. The significance of pericardial dosimetric parameters, but not heart chamber parameters, on survival suggests the potential significance of radiation damage to the cranial region of pericardium.

Dosimetric evaluation and systematic review of radiation therapy techniques for early stage node-negative breast cancer treatment

Radiation therapy (RT) is essential in treating women with early stage breast cancer. Early stage node-negative breast cancer (ESNNBC) offers a good prognosis; hence, late effects of breast RT becomes increasingly important. Recent literature suggests a potential for an increase in cardiac and pulmonary events after RT. However, these studies have not taken into account the impact of newer and current RT techniques that are now available. Hence, this review aimed to evaluate the clinical evidence for each technique and determine the optimal radiation technique for ESNNBC treatment. Currently, six RT techniques are consistently used and studied: 1) prone positioning, 2) proton beam RT, 3) intensity-modulated RT, 4) breath-hold, 5) partial breast irradiation, and 6) intraoperative RT. These techniques show dosimetric promise. However, limited data on late cardiac and pulmonary events exist due to challenges in long-term follow-up. Moving forward, future studies are needed to validate the efficacy and clinical outcomes of these current techniques.

Metformin Protects Against Radiation-Induced Heart Injury and Attenuates the Upregulation of Dual Oxidase Genes Following Rat's Chest Irradiation

Radiation-induced heart toxicity is one of the serious side effects after a radiation disaster or radiotherapy for patients with chest cancers, leading to a reduction in the quality of life of the patients. Evidence has shown that infiltration of inflammatory cells plays a key role in the development of functional damages to the heart via chronic upregulation of some pro-fibrotic and pro-inflammatory cytokines. These changes are associated with continuous free radical production and increased stiffness of heart muscle. IL-4 and IL-13 are two important pro-fibrotic cytokines which contribute to the side effects of ionizing radiation exposure. Recent studies have proposed that IL-4 through upregulation of DUOX2, and IL-13 via stimulation of DUOX1 gene expression, are involved in the development of radiation late effects. In the present study, we aimed to detect changes in the expression of these pathways following irradiation of rat’s heart. Furthermore, we evaluated the possible protective effect of metformin on the development of these abnormal changes. 20 male rats were divided into 4 groups (control, radiation, metformin treated, metformin + radiation). These rats were irradiated with 15 Gy ⁶⁰Co gamma rays, and sacrificed after 10 weeks for evaluation of the changes in the expression of IL4R1, IL-13R2a, DUOX1 and DUOX2. In addition, the levels of IL-4 and IL-13 cytokines, as well as infiltration of macrophages and lymphocytes were detected. Results showed an upregulation of both DUOX1 and DUOX2 pathways in the presence of metformin, while the level of IL-13 did not show any significant change. This was associated with infiltration of macrophages and lymphocytes. Also, treatment with metformin could significantly attenuate accumulation of inflammatory cells, and upregulate these pathways. Therefore, suppression of dual oxidase genes by metformin may be a contributory factor to its protective effect.

Gene expression changes in human iPSC-derived cardiomyocytes after X-ray irradiation

Purpose: Radiation-induced heart disease caused by cardiac exposure to ionizing radiation comprises a variety of cardiovascular effects. Research in this field has been hampered by limited availability of clinical samples and appropriate test models. In this study, we wanted to elucidate the molecular mechanisms underlying electrophysiological changes, which we have observed in a previous study. Materials and methods: We employed RNA deep-sequencing of human-induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) 48 h after 5 Gy X-ray irradiation. By comparison to public data from hiPSC-CMs and human myocardium, we verified the expression of cardiac-specific genes in hiPSC-CMs. Results were validated by qRT-PCR. Results: Differentially gene expression analysis identified 39 and 481 significantly up- and down-regulated genes after irradiation, respectively. Besides, a large fraction of genes associated with cell cycle processes, we identified genes implicated in cardiac calcium homeostasis (PDE3B), oxidative stress response (FDXR and SPATA18) and the etiology of cardiomyopathy (SGCD, BBC3 and GDF15). Conclusions: Notably, observed gene expression characteristics specific to hiPSC-CMs might be relevant regarding further investigations of the response to external stressors like radiation. The genes and biological processes highlighted in our study present promising starting points for functional follow-up studies for which hiPSC-CMs could pose an appropriate cell model when cell type specific peculiarities are taken into account.

The implementation of RapidPlan in predicting deep inspiration breath-hold candidates with left-sided breast cancer

The aim of this study is to determine if RapidPlan (RP) can be used as a prediction method to determine which left-sided supine breast cancer patients would benefit from the deep inspiration breath-hold (DIBH) technique. An RP model database was created with 72 clinically approved 3D conformal radiation therapy (3D-CRT) treatment plans. This model was validated by introducing 10 new patient data sets, creating RP-generated plans and comparing the clinically approved plan for the corresponding patient. The prediction ability of the model was then tested on the free-breathing (FB) scans of patients with clinically approved DIBH plans totaling 29 patients and results were then compared to the FB clinical plan attempts. A statistical analysis performed on the data indicated a strong correlation for the mean heart dose (R² = 0.914; p-value < 0.001) with a standard deviation of 48.6 cGy. After validating the link between physician PTV and mean heart dose, the model was tested clinically on 15 patients by inserting "Test PTV Evals" that were contoured by the researchers as a surrogate for predicting mean heart dose. Statistical analysis showed a strong correlation between the dose to 5% of the heart (D₅) and the mean heart dose (R² values of 0.913 and 0.881, respectively) with a standard deviation for the mean heart dose of 27.2 cGy. It was concluded that by using a Test PTV Eval, the RP-generated plans were able to predict mean heart doses within ± 30.0 cGy.

Acute Coronary Syndrome Management in Cancer Patients

PURPOSE OF REVIEW

Coronary artery disease and cancer often co-exist. Patients with cancer have been excluded by most major cardiology trials and registries and their management remains largely empiric. Cancer patients experience an approximately 10-times increased mortality compared to the general population. Conservative therapy of ACS in cancer therapy results in 1-year mortality of 74%. This review article aims to describe the mechanisms of acute coronary syndromes in cancer patients, their clinical presentation, and their management.

RECENT FINDINGS

Newer studies have shed light on the mechanisms of ACS in cancer patients, which are different and related to the type of malignancy and its associated therapy. Medication-specific coronary effects (vasospasm, endothelial dysfunction, spontaneous thrombosis, accelerated atherosclerosis), radiation vasculitis, cancer cell coronary embolism, and coronary compression from thoracic malignancies are unique ACS mechanisms in cancer patients. Close collaboration between oncologists and cardiologists for thoughtful patient selection and decision making strategies is necessary to provide optimal medical care.

Radiation Matters of the Heart: A Mini Review

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

Impact of Ionizing Radiation on Electrophysiological Behavior of Human-induced Ipsc-derived Cardiomyocytes on Multielectrode Arrays

Cardiac arrhythmia presumably induced through cardiac fibrosis is a recurrent long-term consequence of exposure to ionizing radiation. However, there is also evidence that cardiac arrhythmia can occur in patients shortly after irradiation. In this study, the authors employed multielectrode arrays to investigate the short-term effects of x-ray radiation on the electrophysiological behavior of cardiomyocytes derived from human-induced pluripotent stem cells. These cardiomyocytes with spontaneous pacemaker activity were cultured on single-well multielectrode arrays. After exposure to 0, 0.5, 1, 2, 5, 10 Gy x-ray radiation, electrical activity was measured at time points ranging from 10 min to 96 h. RNA sequencing was employed to verify the expression of genes specifically involved in cardiomyocyte differentiation and function. A decrease in beating rate was observed after irradiation with 5 and 10 Gy starting 48 h after exposure. Cells exposed to higher doses of radiation were more prone to show changes in electrophysiological spatial distribution. No radiation-induced effects with respect to the corrected QT interval were detectable. Gene expression analysis showed up regulation of typical cardiac features like ACTC1 or HCN4. In this study, early dose-dependent changes in electrophysiological behavior were determined after x-ray irradiation. Results point towards a dose-dependent effect on pacemaker function of cardiomyocytes and indicate a possible connection between irradiation and short-term changes in electrophysiological cardiac function. Cardiomyocytes derived from human-induced pluripotent stem cells on multielectrode arrays represent a promising in vitro cardiac-modeling system for preclinical studies.

Advanced imaging modalities to detect cardiotoxicity

Recent advances in cancer treatments have significantly improved survival rates, reemphasizing the focus on reducing the potential complications associated with some therapies. Cardiovascular disease associated with chemotherapies is a major cause of morbidity and mortality in cancer survivors. Early detection of cardiotoxicity improves cardiac outcomes among cancer patients. The review will focus on imaging modalities used to assess cardiotoxicity - the cardiovascular consequences of chemotherapies. The review will discuss the benefits and limitations associated with each technique, as well as the guidelines available to help identify at risk patients. We will discuss novel techniques that may help detect earlier signs of cardiotoxicity, directing management that may improve clinical outcomes.

Radiotherapeutic implications of the updated ICRP thresholds for tissue reactions related to cataracts and circulatory diseases

Radiation therapy of cancer patients involves a trade-off between a sufficient tumour dose for a high probability of local control and dose to organs at risk that is low enough to lead to a clinically acceptable probability of toxicity. The International Commission on Radiological Protection (ICRP) reviewed epidemiological evidence and provided updated estimates of 'practical' threshold doses for tissue injury, as defined at the level of 1% incidence, in ICRP Publication 118. Particular attention was paid to cataracts and circulatory diseases. ICRP recommended nominal absorbed dose threshold for these outcomes as low as 0.5 Gy. Threshold doses for tissue reactions can be reached in some patients during radiation therapy. Modern treatment planning systems do not account for such low doses accurately, and doses to therapy patients from associated imaging procedures are not generally accounted for. While local control is paramount, the observations of ICRP Publication 118 suggest that radiation therapy plans and processes should be examined with particular care. The research needs are discussed in this paper.

Long-term effects of low-dose mouse liver irradiation involve ultrastructural and biochemical changes in hepatocytes that depend on lipid metabolism

The aim of the study was to investigate long-term effects of radiation on the (ultra)structure and function of the liver in mice. The experiments were conducted on wild-type C57BL/6J and apolipoprotein E knock-out (ApoE^-/-) male mice which received a single dose (2 or 8 Gy) of X-rays to the heart with simultaneous exposure of liver to low doses (no more than 30 and 120 mGy, respectively). Livers were collected for analysis 60 weeks after irradiation and used for morphological, ultrastructural, and biochemical studies. The results show increased damage to mitochondrial ultrastructure and lipid deposition in hepatocytes of irradiated animals as compared to non-irradiated controls. Stronger radiation-related effects were noted in ApoE^-/- mice than wild-type animals. In contrast, radiation-related changes in the activity of lysosomal hydrolases, including acid phosphatase, β-glucuronidase, N-acetyl-β-D-hexosaminidase, β-galactosidase, and α-glucosidase, were observed in wild type but not in ApoE-deficient mice, which together with ultrastructural picture suggests a higher activity of autophagy in ApoE-proficient animals. Irradiation caused a reduction of plasma markers of liver damage in wild-type mice, while an increased level of hepatic lipase was observed in plasma of ApoE-deficient mice, which collectively indicates a higher resistance of hepatocytes from ApoE-proficient animals to radiation-mediated damage. In conclusion, liver dysfunctions were observed as late effects of irradiation with an apparent association with malfunction of lipid metabolism.

The role of postoperative radiation therapy for completely resected stage III thymoma and effect of higher heart radiation dose on risk of cardiovascular disease: A retrospective cohort study

OBJECTIVES

This study aimed to assess the efficacy of radiation therapy (RT) in patients with completely resected stage III thymoma and evaluate the relationship between higher heart dose and risk of cardiovascular disease (CVD).

PATIENTS AND METHODS

A total of 130 consecutive patients with Masaoka stage III thymoma were retrospectively reviewed from January 2003 to December 2013. Of these, 99 underwent complete tumor resection [74 received postoperative radiation therapy (S + R) and 25 received surgery alone (S alone)] and 31 patients underwent RT alone (16 due to inoperable tumors and 15 due to high surgical risk or patient refusal; R alone). Three-dimensional conformal RT/intensity-modulated RT was used for patients receiving RT.

RESULTS

The median follow-up for all patients was 70 months. The 5- and 8-year overall survival (OS) rates were 95.6% and 93.9% for S + R, 84.0% and 67.2% for S alone, and 73.3% and 73.3% for R alone (excluding patients with inoperable tumors), respectively (P = 0.004). A trend of improved disease-specific survival (DSS) was also observed in the S + R group compared with the other two groups. CVD was the main nonmalignant cause of death (3/6, 50%). The median time of CVD diagnosis was 101 months after treatment. The mean heart dose was an independent risk factor for CVD.

CONCLUSIONS

Postoperative RT after complete resection improved the survival compared with surgery alone and RT alone for patients with stage III thymoma. A higher heart dose was related to increased risk of CVD in long-term survivors.

Hormesis and radiation safety norms: Comments for an update

Hormesis can be explained by evolutionary adaptation to the current level of a factor present in the natural environment or to some average from the past. This pertains also to ionizing radiation as the natural background has been decreasing during the time of the life existence. DNA damage and repair are normally in a dynamic balance. The conservative nature of the DNA repair suggests that cells may have retained some capability to repair damage from higher radiation levels than that existing today. According to this concept, the harm caused by radioactive contamination would tend to zero with a dose rate tending to a wide range level of the natural radiation background. Existing evidence in favor of hormesis is substantial, experimental data being partly at variance with results of epidemiological studies. Potential bias, systematic errors, and motives to exaggerate risks from low-dose low-rate ionizing radiation are discussed here. In conclusion, current radiation safety norms are exceedingly restrictive and should be revised on the basis of scientific evidence. Elevation of the limits must be accompanied by measures guaranteeing their observance.

Cardiovascular Concerns in BRCA1 and BRCA2 Mutation Carriers

PURPOSE OF REVIEW

BRCA1 and BRCA2 mutation carriers can be at increased cardiovascular risk. The goal of this review is to provide information about factors associated with increased cardiovascular risk, methods to prevent cardiovascular toxicities, and recommended screening guidelines.

RECENT FINDINGS

BRCA1/2 mutation carriers who are diagnosed with cancer are often exposed to chemotherapy, chest radiotherapy, and/or HER2 directed therapies, all of which can be cardiotoxic. In addition, BRCA1/2 carriers often undergo prophylactic salpingoopherectomies, which may also increase cardiovascular risks. Understanding the potential for increased cardiovascular risk in individuals with a BRCA1 or BRCA2 mutation, as well as gold standard practices for prevention, detection, and treatment of cardiac concerns in this population, is important.

WORK PROCEDURES AND RADIATION EXPOSURE AMONG RADIOLOGIC TECHNOLOGISTS IN SOUTH KOREA

This study explored their work characteristics and safety compliance to identify primary factors influencing high occupational radiation exposure among radiologic technologists. A total of 12 387 radiologic technologists were surveyed from 2012 to 2013 in South Korea. Survey data for demographics and work-related characteristics were linked with the National Dose Registry. Multiple regression analysis was used and '% Excess Risk Explained' was calculated to illustrate the degree to which given risk factors explained the relationship of work procedures and radiation exposure. Characteristics of radiologic technologists exposed to higher radiation doses were male, aged <30, working at a general hospital or hospital, and frequently performing routine diagnostic X-ray, CT, portable X-ray and C-arm. Not being completely separated from patients and wearing lead apron was positively associated with higher radiation exposure. Type of facility and safety compliance were the main risk factors for high radiation exposure in performing diagnostic radiologic procedures.

Is Low-Dose Radiation Exposure a Risk Factor for Atherosclerotic Disease?

Nontargeted late effects of radiation include an increased risk of cardiovascular disease, although this is still debatable in the context of low-dose radiation. Tinea capitis patients treated in childhood with X rays to induce scalp epilation received a low dose of radiation to their carotids. To better clarify this issue, we evaluated carotid atherosclerosis in a cohort of such patients treated in 1950-1963 in Portugal. A group of 454 individuals randomly chosen from previously observed Portuguese tinea capitis patients and a control group mainly composed of their spouses (n = 280) were enrolled. Cardiovascular risk factors such as waist circumference, body mass index, blood pressure and tobacco consumption, as well as biochemical measurements were obtained. Ultrasound imaging of carotid arteries for intima media thickness and stenosis evaluation were performed according to a standardized protocol. In comparison to the control group, the irradiated cohort members were significantly older, more frequently never smokers, hypertensive, and presented higher glycated hemoglobin and alkaline phosphatase levels. In addition, the irradiated cohort showed a higher frequency of carotid stenosis ≥30% than the nonirradiated group (13.9% vs. 10.7%), although this was not significant ( P = 0.20). Stenosis was ≥50% in 2.9% of the irradiated group and 0.4% of the nonirradiated group ( P = 0.02). Likewise, the frequency of intima media thickness ≥1 mm was significantly higher in the irradiated group (16.8% vs. 10.7%; P = 0.02). Multivariate analysis, including other cardiovascular risk factors, showed that exposure to low-dose radiation increased the risk of carotid stenosis by ≥50% [odds ratio (OR) = 8.85; P = 0.04] and intima media thickness by ≥1 mm (OR = 1.82; P = 0.02). These findings confirm that low-dose exposure is a risk factor of carotid atherosclerotic disease.

Risk of Coronary Events 55 Years after Thymic Irradiation in the Hempelmann Cohort

Background

Studies of cancer survivors treated with older radiotherapy (RT) techniques (pre-1990s) strongly suggest that ionizing radiation to the chest increases the risk of coronary heart disease (CHD). Our goal was to evaluate the impact of more modern cardiac shielding techniques of RT on the magnitude and timing of CHD risk by studying a cohort exposed to similar levels of cardiac irradiation years ago.

Methods

Between 2004 and 2008, we re-established a population-based, longitudinal cohort of 2657 subjects exposed to irradiation for an enlarged thymus during infancy between 1926 and 1957 and 4388 of their non-irradiated siblings. CHD events were assessed using a mailed survey and from causes of death listed in the National Death Index. We used Poisson regression methods to compare incidence rates by irradiation status and cardiac radiation dose. Results were adjusted for the CHD risk factors of attained-age, sex, diabetes, dyslipidemia hypertension and smoking.

Results

Median age at time of follow-up was 57.5 years (range 41.2–88.8 yrs) for irradiated and non-irradiated siblings. The mean estimated cardiac dose amongst the irradiated was 1.45 Gray (range 0.17–20.20 Gy), with 91% receiving < 3.00 Gy. During a combined 339,924 person-years of follow-up, 213 myocardial infarctions (MI) and 350 CHD events (MI, bypass surgery and angioplasty) occurred. After adjustment for attained age, gender, and other CHD risk factors, the rate ratio for MI incidence in the irradiated group was 0.98 (95%CI, 0.74–1.30), and for any CHD event was 1.07 (95%CI, 0.86–1.32). Higher radiation doses were not associated with more MIs or CHD events in this dose range, in either the crude or the adjusted analyses.

Conclusions

Radiation to the heart during childhood of < 3 Gy, the exposure in most of our cohort, does not increase the lifelong risk of CHD. Reducing cardiac radiation to this amount without increasing other cardiotoxic therapies may eliminate the increased CHD risk associated with radiotherapy for childhood cancer. By extension there is unlikely to be increased CHD risk from relatively higher dose imaging techniques, such as CT, because such techniques use much smaller radiation doses than received by our cohort.

Radiation-Induced Cardiovascular Disease: Mechanisms and Importance of Linear Energy Transfer

Radiation therapy (RT) in the form of photons and protons is a well-established treatment for cancer. More recently, heavy charged particles have been used to treat radioresistant and high-risk cancers. Radiation treatment is known to cause cardiovascular disease (CVD) which can occur acutely during treatment or years afterward in the form of accelerated atherosclerosis. Radiation-induced cardiovascular disease (RICVD) can be a limiting factor in treatment as well as a cause of morbidity and mortality in successfully treated patients. Inflammation plays a key role in both acute and chronic RICVD, but the underling pathophysiology is complex, involving DNA damage, reactive oxygen species, and chronic inflammation. While understanding of the molecular mechanisms of RICVD has increased, the growing number of patients receiving RT warrants further research to identify individuals at risk, plans for prevention, and targets for the treatment of RICVD. Research on RICVD is also relevant to the National Aeronautics and Space Administration (NASA) due to the prevalent space radiation environment encountered by astronauts. NASA's current research on RICVD can both contribute to and benefit from concurrent work with cell and animal studies informing radiotoxicities resulting from cancer therapy. This review summarizes the types of radiation currently in clinical use, models of RICVD, current knowledge of the mechanisms by which they cause CVD, and how this knowledge might apply to those exposed to various types of radiation.

Reproducible Deep-inspiration Breath-hold Irradiation with Forward Intensity-modulated Radiotherapy for Left-sided Breast Cancer Significantly Reduces Cardiac Radiation Exposure Compared to Inverse Intensity-modulated Radiotherapy

Aims and Background

To investigate the objective utility of our clinical routine of reproducible deep-inspiration breath-hold irradiation for left-sided breast cancer patients on reducing cardiac exposure.

Methods and Study Design

Free-breathing and reproducible deep-inspiration breath-hold scans were evaluated for our 10 consecutive left-sided breast cancer patients treated with reproducible deep-inspiration breath-hold. The study was based on the adjuvant dose of 50 Gy in 25 fractions of 2 Gy/fraction. Both inverse and forward intensity-modulated radiotherapy plans were generated for each computed tomography dataset.

Results

Reproducible deep-inspiration breath-hold plans with forward intensity-modulated radiotherapy significantly spared the heart and left anterior descending artery compared to generated free-breathing plans based on mean doses – free-breathing vs reproducible deep-inspiration breath-hold, left ventricle (296.1 vs 94.5 cGy, P = 0.005), right ventricle (158.3 vs 59.2 cGy, P = 0.005), left anterior descending artery (171.1 vs 78.1 cGy, P = 0.005), and whole heart (173.9 vs 66 cGy, P = 0.005), heart V20 (2.2% vs 0%, P = 0.007) and heart V10 (4.2% vs 0.3%, P = 0.007) – whereas they revealed no additional burden on the ipsilateral lung. Reproducible deep-inspiration breath-hold and free-breathing plans with inverse intensity-modulated radiotherapy provided similar organ at risk sparing by reducing the mean doses to the left ventricle, left anterior descending artery, heart, V10-V20 of the heart and right ventricle. However, forward intensity-modulated radiotherapy showed significant reduction in doses to the left ventricle, left anterior descending artery, heart, right ventricle, and contralateral breast (mean dose, 248.9 to 12.3 cGy, P = 0.005). The mean doses for free-breathing vs reproducible deep-inspiration breath-hold of the proximal left anterior descending artery were 1.78 vs 1.08 Gy and of the distal left anterior descending artery were 8.11 vs 3.89 Gy, whereas mean distances to the 50 Gy isodose line of the proximal left anterior descending artery were 6.6 vs 3.3 cm and of the distal left anterior descending artery were 7.4 vs 4.1 cm, with forward intensity-modulated radiotherapy. Overall reduction in mean doses to proximal and distal left anterior descending artery with deep-inspiration breath-hold irradiation was 39% (P = 0.02) and 52% (P = 0.002), respectively.

Conclusions

We found a significant reduction of radiation exposure to the contralateral breast, left and right ventricles, as well as of proximal and especially distal left anterior descending artery with the deep-inspiration breath-hold technique with forward intensity-modulated radiotherapy planning.

Evaluating Cardiac Biomarkers after Chemotherapy and Proton Therapy for Mediastinal Hodgkin Lymphoma

Purpose

Late cardiac complications from thoracic radiation of patients with Hodgkin lymphoma are of great concern. The authors investigated whether cardiac biomarkers could identify patients with early cardiac damage from thoracic radiation.

Materials and Methods

Following completion of anthracycline-based chemotherapy, 14 patients with stage I-IIIA mediastinal Hodgkin lymphoma were enrolled on an IRB-approved prospective trial and agreed to serum evaluation of troponin, CK-MB, and BNP before beginning radiation, after completing radiation, and every 3 to 6 months for 5 years, during follow-up or until relapse.

Results

Among the 14 patients, median follow-up for the entire cohort was 5 years. No evidence in abnormal values in troponin or CK-MB was observed among the patient cohort. BNP levels demonstrated statistically significant higher values at various follow-up time points. Higher levels of BNP were observed among patients receiving higher anthracycline doses (>250 mg), but not among patients with higher mean heart radiation doses.

Conclusions

In the first 5 years after treatment, no rise in CK-MB or troponin was identified. BNP levels significantly increased following treatment, with larger increases among patients who received higher doses of anthracyclines. Further investigation is warranted.

Management of CAD in Patients with Active Cancer: the Interventional Cardiologists' Perspective

PURPOSE OF REVIEW

Coronary artery disease in patients with active cancer presents particular challenges for clinicians, as optimum management is required in order to treat the underlying malignancy and to reduce morbidity and mortality associated with cardiovascular diseases. Special considerations must be made in respect to either primary or secondary thrombocytopenia, the presence of coagulopathies and the propensity of bleeding, vascular access complications, and increased risk of stent thrombosis.

RECENT FINDINGS

In presence of acute coronary symptoms, the cardio-oncology team has to make a complex decision between conservative medical management or early angiography (within 24 h) and revascularization. There is a lack of reliable data on the outcomes of patients with active cancer who undergo invasive procedures for the diagnostic and treatment of coronary artery disease. Cardiac catheterization recommendations in cancer patients are being currently elaborated by cardio-oncologists in order to improve the overall survival in cancer patients with coronary artery disease.

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

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Cardiovascular Complications of Cancer Therapy: Best Practices in Diagnosis, Prevention, and Management: Part 2

In this second part of a 2-part review, we will review cancer or cancer therapy-associated systemic and pulmonary hypertension, QT prolongation, arrhythmias, pericardial disease, and radiation-induced cardiotoxicity. This review is based on a MEDLINE search of published data, published clinical guidelines, and best practices in major cancer centers. Newly developed targeted therapy can exert off-target effects causing hypertension, thromboembolism, QT prolongation, and atrial fibrillation. Radiation therapy often accelerates atherosclerosis. Furthermore, radiation can damage the heart valves, the conduction system, and pericardium, which may take years to manifest clinically. Management of pericardial disease in cancer patients also posed clinical challenges. This review highlights the unique opportunity of caring for cancer patients with heart problems caused by cancer or cancer therapy. It is an invitation to action for cardiologists to become familiar with this emerging subspecialty.

How radiation influences atherosclerotic plaque development: a biophysical approach in ApoE⁻/⁻ mice

Atherosclerosis is the development of lipid-laden plaques in arteries and is nowadays considered as an inflammatory disease. It has been shown that high doses of ionizing radiation, as used in radiotherapy, can increase the risk of development or progression of atherosclerosis. To elucidate the effects of radiation on atherosclerosis, we propose a mathematical model to describe radiation-promoted plaque development. This model distinguishes itself from other models by combining plaque initiation and plaque growth, and by incorporating information from biological experiments. It is based on two consecutive processes: a probabilistic dose-dependent plaque initiation process, followed by deterministic plaque growth. As a proof of principle, experimental plaque size data from carotid arteries from irradiated ApoE[Formula: see text] mice was used to illustrate how this model can provide insight into the underlying biological processes. This analysis supports the promoting role for radiation in plaque initiation, but the model can easily be extended to include dose-related effects on plaque growth if available experimental data would point in that direction. Moreover, the model could assist in designing future biological experiments on this research topic. Additional biological data such as plaque size data from chronically-irradiated mice or experimental data sets with a larger variety in biological parameters can help to further unravel the influence of radiation on plaque development. To the authors' knowledge, this is the first biophysical model that combines probabilistic and mechanistic modeling which uses experimental data to investigate the influence of radiation on plaque development.

Radiation dose to heart base linked with poorer survival in lung cancer patients

BACKGROUND

Advances in radiotherapy (RT) have allowed an increased proportion of lung cancer patients to be treated curatively. High doses delivered to critical thoracic organs can result in excess mortality with tolerance doses poorly defined. This work presents a novel method of identifying anatomical dose-sensitive regions within the thorax.

METHODS

A high-resolution, normal-tissue dosimetric analysis was performed to identify regions in the heart that correlate with poorer survival. A total of 1101 patients treated with curative-intent RT were selected and all computed tomography imaging and dose distributions were deformed to a reference. Mean dose distributions were created for patients who survived versus those who did not at a set time point. Statistical significance of dose differences was investigated with permutation testing. The dose received by the most statistically significant region of the thorax was collected in all patients and included in a multivariate survival analysis.

RESULTS

The permutation testing showed a highly significant region across the base of the heart, where higher doses were associated with worse patient survival (p < 0.001). Cox-regression multivariate analysis showed region dose, tumour volume, performance status and nodal stage were significant factors associated with survival, whereas cardiac mean dose, V5 and V30 showed no significance. Survival curves, controlling for these factors, were plotted with patients receiving doses greater than 8.5 Gy to the identified region showing worse survival (log-rank p < 0.001, hazard ratio 1.2).

CONCLUSION

The application of this novel methodology in lung cancer patients identifies the base of the heart as a dose-sensitive region for the first time.

Circulatory disease in French nuclear fuel cycle workers chronically exposed to uranium: a nested case–control study

Objectives

There is growing evidence of an association between low-dose external γ-radiation and circulatory system diseases (CSDs), yet sparse data exist about an association with chronic internal uranium exposure and the role of non-radiation risk factors. We conducted a nested case–control study of French AREVA NC Pierrelatte nuclear workers employed between 1960 and 2005 to estimate CSD risks adjusting for major CSD risk factors (smoking, blood pressure, body mass index, total cholesterol and glycaemia) and external γ-radiation dose.

Methods

The study included 102 cases of death from CSD and 416 controls individually matched on age, gender, birth cohort and socio-professional status. Information on CSD risk factors was collected from occupational medical records. Organ-specific absorbed doses were estimated using biomonitoring data, taking into account exposure regime and uranium physicochemical properties. External γ-radiation was measured by individual dosimeter badges. Analysis was conducted with conditional logistic regression.

Results

Workers were exposed to very low radiation doses (mean γ-radiation dose 2 and lung uranium dose 1 mGy). A positive but imprecise association was observed (excess OR per mGy 0.2, 95% CI 0.004 to 0.5). Results obtained after adjustment suggest that uranium exposure might be an independent CSD risk factor.

Conclusions

Our results suggest that a positive association might exist between internal uranium exposure and CSD mortality, not confounded by CSD risk factors. Future work should focus on numerous uncertainties associated with internal uranium dose estimation and on understanding biological pathway of CSD after protracted low-dose internal radiation exposure.

Heart irradiation reduces microvascular density and accumulation of HSPA1 in mice

PURPOSE

Improvement of radiotherapy techniques reduces the exposure of normal tissues to ionizing radiation. However, the risk of radiation-related late effects remains elevated. In the present study, we investigated long-term effects of radiation on heart muscle morphology.

MATERIALS AND METHODS

We established a mouse model to study microvascular density (MVD), deposition of collagen fibers, and changes in accumulation of heat shock 70 kDa protein 1 (HSPA1) in irradiated heart tissue. Hearts of C57BL/6 mice received a single dose of X‑ray radiation in the range 0.2-16 Gy. Analyses were performed 20, 40, and 60 weeks after irradiation.

RESULTS

Reduction in MD was revealed as a long-term effect observed 20-60 weeks after irradiation. Moreover, a significant and dose-dependent increase in accumulation of HSPA1, both cytoplasmic and nuclear, was observed in heart tissues collected 20 weeks after irradiation. We also noticed an increase in collagen deposition in hearts treated with higher doses.

CONCLUSIONS

This study shows that some changes induced by radiation in the heart tissue, such as reduction in microvessel density, increase in collagen deposition, and accumulation of HSPA1, are observed as long-term effects which might be associated with late radiation cardiotoxicity.