Cardiovascular effects of breast cancer radiotherapy

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Effects of different types of radiation therapy on cardiac-specific death in patients with thyroid malignancy

Radiation therapy (RT) is one of the common and widely used treatment method for thyroid tumors. Considering that the thyroid is located close to the heart, the radiation generated during the treatment of thyroid tumors may have an adverse greater impact on the heart. This study is to explore the influencing factors, especially additional effects of RT, on cardiac-specific death among patients with malignant thyroid tumors. Collecting information from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database using SEER*Stat. Patients with malignant thyroid tumors were searched, whether receiving RT or not. Ultimately, 201, 346 eligible patients were included. Propensity Score Matching (PSM) was used to minimize bias of baseline characteristics by adjusting for confounding factors. COX (proportional hazards) and fine-gray (competing risk) model regression analysis were used to explore the effects of various influencing factors on cardiac-specific death. The present analysis showed that, compared with non-RT, RT based upon radioactive implants and beam radiation were associated with lower risk of cardiac-specific death in patients with thyroid malignancy, beam radiation therapy may had a similar effect. Besides, the remaining RT methods did not significantly increase the risk of cardiac-specific death. In addition, Asian or Pacific Islander ethnicity, female sex, marital status, combined summary stage (localized, regional, and distant), high-income, and later year of diagnosis were associated with lower risk of cardiac-specific death. While older age of diagnosis, African ethnicity, non-Hispanic ancestry, and derived AJCC stage (IV) were risk factors for cardiac-specific death. These results help to identify the factors influencing cardiac-specific death among patients with thyroid malignancies. Furthermore, it may helps to improve the clinical application of RT without too much concern about adverse cardiac effects.

Effect of radiotherapy on cardiac-specific death in patients with non-malignant tumors of central nervous system and related clinical features

Importance

Cardiac-specific death from radiation caused by radiation therapy (RT) in patients with malignant tumors has received extensive attention, however, little is known regarding the potential cardiotoxic effects of RT in patients with non-malignant tumors.

Objectives and methods

In this study, we used the SEER data to explore the incidence of post-radiation cardiovascular complications in patients with non-malignant tumors of central nervous system (CNS), and identify the influencing factors of cardiac-specific death.

Results

Ultimately 233, 306 patients were included (97.8% of patients had brain tumors and 2.2% had spinal cord tumors). For patients with non-malignant tumors of CNS, RT {yes (odds ratio [OR] 0.851, 95% confidence interval [CI] 0.774–0.936, p = 0.001, before propensity score matching (PSM); OR 0.792, 95% CI 0.702–0.894, p < 0.001, after PSM) vs. no} was associated with lower risk of cardiac-specific death, other clinical features affecting cardiac death similar to those in patients with non-malignant tumors of CNS receiving RT. For patients with non-malignant tumors of CNS receiving RT, female, married status, Hispanic ethnicity, surgery, and tumor site (brain exclude nerve and endocrine, nervous system) were associated with lower risks of cardiac-specific death, while earlier year of diagnosis, older age of diagnosis, Black, larger tumor and bilateral tumor were risk factors for cardiac-specific death.

Conclusions

Our study shows the influencing factors for cardiac-specific death in patients with non-malignant tumors of CNS, and found RT is associated with lower risk of cardiac-specific death. These results can facilitate the identification of patients with non-malignant tumors of CNS who can benefit from RT while avoiding cardiovascular events. In addition, this study helps to enhance the clinical use of RT in these populations, especially in patients who may have impaired cardiac function due to CNS tumors.

Deep inspiration breath hold in post-operative radiotherapy for right breast cancer: a retrospective analysis

Background

The aim of our study is to determine whether deep inspiration breath hold (DIBH) is effective for reducing exposure of the heart, left coronary artery (LAD) and both lungs in right breast radiotherapy.

Materials and methods

We have analyzed 10 consecutive patients with right-sided breast cancer (BC), simulated during free breathing (FB) and in DIBH modality. For all patients we contoured breast PTV and organs at risk (right and left lungs, heart, LAD) on both CT scans (FB and DIBH). Finally, 5 patients were treated with IMRT and 5 with VMAT techniques.

Results

All patients were able to end the treatments in DIBH modalities regardless of the longer treatment time in comparison to FB. The maximum and mean dose to the heart are lower in the DIBH modality. The mean values of the heart mean dose were 1.76 Gy in DIBH and 2.19 Gy in FB. The mean heart maximum dose in DIBH and FB were, respectively, 9.3 Gy and 11 Gy. Likewise, the maximum dose to the LAD is lower in DIBH; 2.57 Gy versus 3.56 Gy in FB. Noteworthy, 3 patients with hepatomegaly treated with the DIBH technique showed a higher ipsilateral lung dose than FB, but a decrease of liver dose.

Conclusion

We report that the use of DIBH for right-sided BC allows the dose to the heart, LAD and to the liver to be reduced in case of hepatomegaly. This technique is well tolerated by patients, when adequately trained, and could be considered effective even in right sided BC.

Cost-effectiveness of using protons for breast irradiation aiming at minimizing cardiotoxicity: A risk-stratification analysis

Background

Incidental exposure of the heart to ionizing irradiation is associated with an increased risk of ischemic heart disease and subsequent fatality in patients with breast cancer after radiotherapy. Proton beam therapy can limit the heart dose in breast irradiation to a negligible level. However, compared with conventional photon modality, proton breast irradiation is more expensive. In this study, we performed cost-effectiveness analyses to identify the type of patients who would be more suitable for protons.

Methods

A Markov decision model was designed to evaluate the cost-effectiveness of protons vs. photons in reducing the risk of irradiation-related ischemic heart disease. A baseline evaluation was performed on a 50-year-old woman patient without the preexisting cardiac risk factor. Furthermore, risk-stratification analyses for photon mean heart dose and preexisting cardiac risk were conducted on 40-, 50-, and 60-year-old women patients under different proton cost and willingness-to-pay (WTP) settings.

Results

Using the baseline settings, the incremental effectiveness (protons vs. photons) increased from 0.043 quality-adjusted life-year (QALY) to 0.964 QALY when preexisting cardiac risk increased to 10 times its baseline level. At a proton cost of 50,000 US dollars ($), protons could be cost-effective for ≤ 60-year-old patients with diabetes and ≤50-year-old patients with grade II–III hypertension at the WTP of China ($37,653/QALY); for ≤ 60-year-old patients with diabetes and ≤ 50-year-old patients with grade II–III hypertension or ≥ 2 major cardiac risk factors at a WTP of $50,000/QALY; and for ≤ 60-year-old patients with diabetes, grade II–III hypertension or ≥ 2 major cardiac risk factors and ≤ 50-year-old patients with total cholesterol ≥ 240 mg/dL at a WTP of $100,000/QALY.

Conclusion

Patients' preexisting cardiac risk status was a key factor affecting the cardiac benefits gained from protons and should therefore be a major consideration for the clinical decision of using protons; cost-effective scenarios of protons exist in those patients with high risk of developing cardiac diseases.

Association between the cardiac contact distance and the maximum dose at the left anterior descending coronary artery in post mastectomized patients

The clinical information on the relationship between the cardiac contact distance (CCD), the maximum dose (D_max) delivered to the left anterior descending (LAD) coronary artery and the mean heart dose has mostly focused on patients with breast-conserving surgery (BCS), being scarce in postmastectomy patients. The aim of this study is to determine the association between the CCD and the D_max delivered to the LAD. The secondary objective was to evaluate the dosimetric results of comparing three-dimensional conformal radiotherapy (3D-CRT) to intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques for post mastectomized breast cancer patients with irradiation to the left chest wall. 53 cases of women who received adjuvant standard fractionated postmastectomy radiotherapy (PMRT) were used. Three types of plans were created for each patient: 3D-CRT, seven equidistant IMRT fields, and four partial VMAT arcs. Correlations were evaluated using Pearson's correlation coefficient. Plans made with IMRT and VMAT showed improved homogeneity and conformity. Associations between CCD and D_max to LAD were positive for all three plan types. Compared to 3D-CRT, the modulated intensity plans obtained better dose homogeneity and conformity to the target volume. The LAD and heart doses were significantly lower for IMRT and VMAT plans. The CCD can be used as a predictor of the maximum and mean doses of the LAD. Modulated intensity techniques allow for better dose distribution and dose reduction to the heart and LAD.

Correlation between the secondary structure and surface activity of β-sheet forming cationic amphiphilic peptides and their anticancer activity

Cancer is one of the main causes of death worldwide. The current cancer treatment strategies often lack selectivity for cancer cells resulting in dose-limiting adverse effects and reduced quality of life. Recently, anticancer peptides (ACPs) have emerged as an alternative treatment with higher selectivity, less adverse effects, and lower propensity for drug resistance. However, most of the current studies on the ACPs are focused on α-helical ACPs and there is lack of systematic studies on β-sheet forming ACPs. Herein we report the development of a new series of rationally designed short cationic amphiphilic β-sheet forming ACPs and their structure activity relationship. The peptides had the general formula (XY₁XY₂)₃, with X representing hydrophobic amino acids (isoleucine (I) or leucine (L)), Y₁ and Y₂ representing cationic amino acids (arginine (R) or lysine (K)). The cytotoxicity of the designed ACPs in HCT 116 colorectal cancer, HeLa cervical cancer and human dermal fibroblast (HDF) cells was assessed by MTT test. The physicochemical properties of the peptides were characterized by various techniques including RP-HPLC, LC-MS, and Circular Dichroism (CD) spectroscopy. The surface activity of the peptides at the air-water interface and their interaction with the lipid monolayers as models for cell membranes were studied by Langmuir trough. The peptides consisting of I with R and K had selective anticancer activity while the combination of L and R diminished the anticancer activity of the peptides but rendered them more toxic to HDFs. The anticancer activity of the peptides was directed by their surface activity (amphiphilicity) and their secondary structure in hydrophobic surfaces including cancer cell membranes. The selectivity of the peptides for cancer cells was a result of their higher penetration into cancer cell membranes compared to normal cell membranes. The peptides exerted their anticancer activity by disrupting the mitochondrial membranes and eventually apoptosis. The results presented in this study provide an insight into the structure-activity relationship of this class of ACPs which can be employed as guidance to design new ACPs with improved anticancer activity and lower toxicity against normal cells.

Rationally designed short cationic α-helical peptides with selective anticancer activity

HYPOTHESIS

Naturally derived or synthetic anticancer peptides (ACPs) have emerged as a new generation of anticancer agents with higher selectivity for cancer cells and less propensity for drug resistance. Despite the structural diversity of ACPs, α-helix is the most common secondary structure among them. Herein we report the development of a new library of short cationic amphiphilic α-helical ACPs with selective cytotoxicity against colorectal and cervical cancer.

EXPERIMENTS

The peptides had a general formula C(XXYY)₃ with C representing amino acid cysteine (providing a -SH group for molecular conjugation), X representing hydrophobic amino acids (isoleucine (I) or leucine (L)), and Y representing cationic amino acids (arginine (R) or lysine (K)). Two variants of the peptides were synthesized by adding additional Isoleucine residues to the C-terminal and replacing the N-terminal cysteine with LC-propargylglycine (LC-G) to investigate the effect of N-terminal and C-terminal variation on the anticancer activity. The structure and physicochemical properties of the peptides were determined by RP-HPLC, LC-MS and CD spectroscopy. The cytotoxicity of the peptides in different cell lines was assessed by MTT test, cell proliferation assay and mitochondrial damage assay. The mechanism of cell selectivity of the peptides was investigated by studying their interfacial behaviour at the air/water and lipid/water interface using Langmuir trough.

FINDINGS

The peptides consisting of K residues in their hydrophilic domains exhibited more selective anticancer activity whereas the peptides containing R exhibited strong toxicity in normal cells. The anticancer activity of the peptides was a function of their helical content and their hydrophobicity. Therefore, the addition of two I residues at C-terminal enhanced the anticancer activity of the peptides by increasing their hydrophobicity and their helical content. These two variants also exhibited strong anticancer activity against colorectal cancer multicellular tumour spheroids (MCTS). The higher toxicity of the peptides in cancer cells compared to normal cells was the result of higher penetration into the negatively charged cancer cell membranes, leading to higher cellular uptake, and their cytotoxic effect was mainly exerted by damaging the mitochondrial membranes leading to apoptosis. The results from this study provide a basis for rational design of new α-helical ACPs with enhanced anticancer activity and selectivity.

The advantages of abdominal compression with shallow breathing during left-sided postmastectomy radiotherapy by Helical TomoTherapy

BACKGROUND

Left-sided post-mastectomy radiotherapy (PMRT) certainly precedes some radiation dose to the cardiopulmonary organs causing many side effects. To reduce the cardiopulmonary dose, we created a new option of the breathing adapted technique by using abdominal compression applied with a patient in deep inspiration phase utilizing shallow breathing. This study aimed to compare the use of abdominal compression with shallow breathing (ACSB) with the free breathing (FB) technique in the left-sided PMRT.

MATERIALS AND METHODS

Twenty left-sided breast cancer patients scheduled for PMRT were enrolled. CT simulation was performed with ACSB and FB technique in each patient. All treatment plans were created on a TomoTherapy planning station. The target volume and dose, cardiopulmonary organ volume and dose were analyzed. A linear correlation between cardiopulmonary organ volumes and doses were also tested.

RESULTS

Regarding the target volumes and dose coverage, there were no significant differences between ACSB and FB technique. For organs at risk, using ACSB resulted in a significant decrease in mean (9.17 vs 9.81 Gy, p<0.0001) and maximum heart dose (43.79 vs 45.45 Gy, p = 0.0144) along with significant reductions in most of the evaluated volumetric parameters. LAD doses were also significantly reduced by ACSB with mean dose 19.24 vs 21.85 Gy (p = 0.0036) and the dose to 2% of the volume (D2%) 34.46 vs 37.33 Gy (p = 0.0174) for ACSB and FB technique, respectively. On the contrary, the lung dose metrics did not show any differences except the mean V5 of ipsilateral lung. The positive correlations were found between increasing the whole lung volume and mean heart dose (p = 0.05) as well as mean LAD dose (p = 0.041) reduction.

CONCLUSIONS

The ACSB technique significantly reduced the cardiac dose compared with the FB technique in left-sided PMRT treated by Helical TomoTherapy. Our technique is uncomplicated, well-tolerated, and can be applied in limited resource center.

Cardiovascular Consequences of Skeletal Muscle Impairments in Breast Cancer

Breast cancer survivors suffer from disproportionate cardiovascular disease risk compared to age-matched controls. Beyond direct cardiotoxic effects due to treatments such as chemotherapy and radiation, breast-cancer-related reductions in skeletal muscle mass, quality and oxidative capacity may further contribute to cardiovascular disease risk in this population by limiting the ability to engage in aerobic exercise—a known promoter of cardiovascular health. Indeed, 20–30% decreases in peak oxygen consumption are commonly observed in breast cancer survivors, which are indicative of exercise intolerance. Thus, breast-cancer-related skeletal muscle damage may reduce exercise-based opportunities for cardiovascular disease risk reduction. Resistance training is a potential strategy to improve skeletal muscle health in this population, which in turn may enhance the capacity to engage in aerobic exercise and reduce cardiovascular disease risk.

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.

BNP as a potential biomarker for cardiac damage of breast cancer after radiotherapy: a meta-analysis

BACKGROUND

To analyze whether BNP could be a potential biomarker for cardiac damage of breast cancer after radiotherapy.

METHODS

PubMed, Web of Science, ProQuest and Medline were searched using the key words "breast cancer" ("breast tumor", "breast neoplasm", or "breast carcinoma"), "brain natriuretic peptide" (or BNP) and "radiotherapy" (or "radiation therapy"). Four articles were selected and analyzed using the STATA 12.0 software package. The standard mean difference (SMD) and its standard error for BNP were calculated to assess the relationship between BNP and radiotherapy for breast cancer patients.

RESULTS

In total, 172 patients with breast cancer were identified. The pooled SMD was -0.233 (95% CI -1.113, -0.057). The pooled estimated SMD for all studies showed obvious significant difference (z = 3.99, P = .000). There was no publication bias.

CONCLUSIONS

This meta-analysis suggested that BNP could be a biomarker of cardiac damage at high heart absorbed doses according to radiotherapy, especially for left breast cancer patients.

The heart's exposure to radiation increases the risk of cardiac toxicity after chemoradiotherapy for superficial esophageal cancer: a retrospective cohort study

Background

Chemoradiotherapy effectively treats superficial esophageal cancer and is optimal to preserve organs. However, late toxicity, particularly in cardiac diseases, obstructs clinical outcomes. We revealed the risk factors for cardiac event development post-chemoradiotherapy.

Methods

Data from 80 patients who were diagnosed with submucosal invasive esophageal cancer without metastasis (confirmed using multiple modalities) and who underwent chemoradiotherapy between 2006 and 2014 were analyzed. Patients were 11% (9/80) female, and the median age and follow-up were 66.5 y and 73 mo, respectively. We calculated the individual radiation dose to the heart and analyzed relationships between the cardiac event occurrence rate and each clinical factor.

Results

The 5-y overall and recurrence-free survival rates were 74.6 and 62.4%, respectively. Among the total number of deaths, 34.6% was caused by esophageal cancer. During the follow-up, 13 patients developed severe cardiac events (ischemic heart diseases, n = 7; pericardial effusion, n = 3, atrial fibrillation, n = 1; and sudden death, n = 2). The significant risk factor for cardiac events post-chemoradiotherapy was the level of the heart’s exposure to radiation, with higher exposure associated with greater occurrence. History of smoking, obesity, comorbidity, and history of cardiac disease were unrelated to cardiac event occurrence post-chemoradiotherapy.

Conclusions

Chemoradiotherapy is a favorable intervention for superficial esophageal cancer. Reducing the radiation dose to the heart likely contributes to preventing cardiac toxicity post-chemoradiotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5421-y) contains supplementary material, which is available to authorized users.

Regulation of microRNAs by molecular hydrogen contributes to the prevention of radiation-induced damage in the rat myocardium

microRNAs (miRNAs) constitute a large class of post-transcriptional regulators of gene expression. It has been estimated that miRNAs regulate up to 30% of the protein-coding genes in humans. They are implicated in many physiological and pathological processes, including those involved in radiation-induced heart damage. Biomedical studies indicate that molecular hydrogen has potential as a radioprotective agent due to its antioxidant, anti-inflammatory, and signal-modulating effects. However, the impact of molecular hydrogen on the expression of miRNAs in the heart after irradiation has not been investigated. This study aimed to explore the involvement of miRNA-1, -15b, and -21 in the protective action of molecular hydrogen on rat myocardium damaged by irradiation. The results showed that the levels of malondialdehyde (MDA) and tumor necrosis factor alpha (TNF-α) increased in the rat myocardium after irradiation. Treatment with molecular hydrogen-rich water (HRW) reduced these values to the level of non-irradiated controls. miRNA-1 is known to be involved in cardiac hypertrophy, and was significantly decreased in the rat myocardium after irradiation. Application of HRW attenuated this decrease in all evaluated time periods. miRNA-15b is considered to be anti-fibrotic, anti-hypertrophic, and anti-oxidative. Irradiation downregulated miRNA-15b, whereas administration of HRW restored these values. miRNA-21 is connected with cardiac fibrosis. We observed significant increase in miRNA-21 expression in the irradiated rat hearts. Molecular hydrogen lowered myocardial miRNA-21 levels after irradiation. This study revealed for the first time that the protective effects of molecular hydrogen on irradiation-induced heart damage may be mediated by regulating miRNA-1, -15b, and -21.

Greater Odds for Angina in Uranium Miners Than Nonuranium Miners in New Mexico

OBJECTIVE

The aim of this study was to test the hypothesis that uranium miners in New Mexico (NM) have a greater prevalence of cardiovascular disease than miners who extracted the nonuranium ore.

METHODS

NM-based current and former uranium miners were compared with nonuranium miners by using cross-sectional standardized questionnaire data from the Mining Dust in the United States (MiDUS) study from 1989 to 2016.

RESULTS

Of the 7215 eligible miners, most were men (96.3%). Uranium miners (n = 3151, 43.7%) were older and diabetic, but less likely to currently smoke or use snuff (P ≤ 0.001 for all). After adjustment for covariates, uranium miners were more likely to report angina (odds ratio 1.51, 95% confidence interval 1.23 to 1.85) than nonuranium miners.

CONCLUSION

Our data suggest that along with screening for pulmonary diseases, uranium industry workers should be screened for cardiovascular diseases.

Impact of radiotherapy on cardiovascular health of women with breast cancer

INTRODUCTION

This study aims to examine the impact of radiotherapy on the cardiovascular health of women diagnosed with breast cancer in the Waikato region in New Zealand.

METHODS

Women diagnosed with stage 0-III breast cancer and recorded in the Waikato Breast Cancer Registry were divided into two groups: a radiotherapy group and a no-radiotherapy group. Baseline characteristics and treatments were compared in the two groups. Kaplan-Meier survival analysis was performed to compare cardiovascular morbidity and mortality. Cox Proportional Hazard regression analysis was used to estimate the hazard ratio of radiotherapy on the risk of cardiovascular morbidity and mortality while adjusting for other factors.

RESULTS

A total of 3528 women were included in this study, with 2303 in the radiotherapy group and 1225 in the no-radiotherapy group. At 10-year follow-up, 11.7% of women in the radiotherapy group and 19.4% in the no-radiotherapy group experienced cardiovascular events. Only 2.3% of patients who received radiotherapy died of cardiovascular disease by 10 years compared to 7.0% in the no-radiotherapy group. After adjusting for clinically significant factors, there was unexplained reduced risk of developing cardiovascular disease in the radiotherapy group compared to the no-radiotherapy group (HR 0.73, 95% CI: 0.59-0.92). No significant difference was found in cardiovascular mortality between the two groups.

CONCLUSIONS

Radiotherapy appears less likely to be offered to patients at higher risk of cardiovascular disease. No evidence of increased risk of a cardiovascular event was found in the group of women with breast cancer treated with radiotherapy and current regimens appear safe. Traditional cardiovascular risk factors remain the main culprits in this setting. Clinicians should work with patients in managing these risk factors for optimal results.

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.

Cardiovascular complications after radiotherapy

Over the past decades, effective cancer therapies have resulted in a significant improvement in the survival rates for a number of cancers and an increase in the number of cancer survivors. Radiation therapy is widely used in the treatment of cancer, and it can induce various cardiotoxicities that differ considerably from chemotherapy-induced cardiotoxicity. They occur primarily as late radiation-induced complications, several years from the end of anticancer treatment and present as coronary artery disease, heart failure, pericardial disease, valvular heart disease and arrhythmias. Patients who recovered from cancer disease suffer from cardiac complications of anticancer treatment, it affects the quality of their lives and life expectancy, especially if the diagnosis is delayed. These patients may present distinct symptoms of cardiac injury, resulting from radiation-induced neurotoxicity and altered pain perception, which makes diagnosis difficult. This review highlights the need for a screening programme for patients who have undergone radiation therapy and which will subsequently have a potentially profound impact on morbidity and mortality.

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.

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.

Evaluation of a mixed beam therapy for postmastectomy breast cancer patients: Bolus electron conformal therapy combined with intensity modulated photon radiotherapy and volumetric modulated photon arc therapy

PURPOSE

The purpose of this study was to assess the potential benefits and limitations of a mixed beam therapy, which combined bolus electron conformal therapy (BECT) with intensity modulated photon radiotherapy (IMRT) and volumetric modulated photon arc therapy (VMAT), for left-sided postmastectomy breast cancer patients.

METHODS

Mixed beam treatment plans were produced for nine postmastectomy radiotherapy (PMRT) patients previously treated at our clinic with VMAT alone. The mixed beam plans consisted of 40 Gy to the chest wall area using BECT, 40 Gy to the supraclavicular area using parallel opposed IMRT, and 10 Gy to the total planning target volume (PTV) by optimizing VMAT on top of the BECT + IMRT dose distribution. The treatment plans were created in a commercial treatment planning system (TPS), and all plans were evaluated based on PTV coverage, dose homogeneity index (DHI), conformity index (CI), dose to organs at risk (OARs), normal tissue complication probability (NTCP), and secondary cancer complication probability (SCCP). The standard VMAT alone planning technique was used as the reference for comparison.

RESULTS

Both techniques produced clinically acceptable PMRT plans but with a few significant differences: VMAT showed significantly better CI (0.70 vs 0.53, P < 0.001) and DHI (0.12 vs 0.20, P < 0.001) over mixed beam therapy. For normal tissues, mixed beam therapy showed better OAR sparing and significantly reduced NTCP for cardiac mortality (0.23% vs 0.80%, P = 0.01) and SCCP for contralateral breast (1.7% vs 3.1% based on linear model, and 1.2% vs 1.9% based on linear-exponential model, P < 0.001 in both cases), but showed significantly higher mean (50.8 Gy vs 49.3 Gy, P < 0.001) and maximum skin doses (59.7 Gy vs 53.3 Gy, P < 0.001) compared with VMAT. Patients with more tissue (minimum distance between the distal PTV surface and lung approximately > 0.5 cm and volume of tissue between the distal PTV surface and heart or lung approximately > 250 cm³ ) between distal PTV surface and lung may benefit the most from mixed beam therapy.

CONCLUSION

This work has demonstrated that mixed beam therapy (BECT + IMRT:VMAT = 4:1) produces clinically acceptable plans having reduced OAR doses and risks of side effects compared with VMAT. Even though VMAT alone produces more homogenous and conformal dose distributions, mixed beam therapy remains as a viable option for treating postmastectomy patients, possibly leading to reduced normal tissue complications.

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.

Optical metabolic imaging of irradiated rat heart exposed to ischemia-reperfusion injury

Whole thoracic irradiation (WTI) is known to cause deterioration in cardiac function. Whether irradiation predisposes the heart to further ischemia and reperfusion (IR) injury is not well known. The aim of this study is to examine the susceptibility of rat hearts to IR injury following a single fraction of 15 Gy WTI and to investigate the role of mitochondrial metabolism in the differential susceptibility to IR injury. After day 35 of irradiation, ex vivo hearts from irradiated and nonirradiated rats (controls) were exposed to 25-min global ischemia followed by 60-min IR, or hearts were perfused without IR for the same protocol duration [time controls (TC)]. Online fluorometry of metabolic indices [redox state: reduced nicotinamide adenine dinucleotide (NADH), oxidized flavin adenine dinucleotide (FAD), and NADH/FAD redox ratio] and functional variables [systolic left ventricular pressure (LVP), diastolic LVP (diaLVP), coronary flow (CF), and heart rate were recorded in the beating heart; developed LVP (dLVP) and rate pressure product (RPP)] were derived. At the end of each experimental protocol, hearts were immediately snap frozen in liquid N2 for later three-dimensional imaging of the mitochondrial redox state using optical cryoimaging. Irradiation caused a delay in recovery of dLVP and RPP after IR when compared to nonirradiated hearts but recovered to the same level at the end of reperfusion. CF in the irradiated hearts recovered better than the control hearts after IR injury. Both fluorometry and 3-D cryoimaging showed that in WTI and control hearts, the redox ratio increased during ischemia (reduced) and decreased on reperfusion (oxidized) when compared to their respective TCs; however, there was no significant difference in the redox state between WTI and controls. In conclusion, our results show that although irradiation of rat hearts compromised baseline cardiovascular function, it did not alter cardiac mitochondrial redox state and induce greater susceptibility of these hearts to IR injury.

The feasibility of a heart block with an electron compensation as an alternative whole breast radiotherapy technique in patients with underlying cardiac or pulmonary disease

PURPOSE

We aimed to evaluate the feasibility of the heart block with electron compensation (HBE) technique, based on three-dimensional conformal radiotherapy (3D-CRT) in left-sided breast cancer patients with underlying cardiac or pulmonary disease.

METHODS

Twenty patients with left-sided breast cancer who were treated with whole breast radiotherapy (WBRT) were included in this study. Intensity-modulated radiotherapy (IMRT), 3D-CRT, and HBE treatment plans were generated for each patient. Based on the 3D-CRT plan, the HBE plan included a heart block from the medial tangential field to shield the heart and added an electron beam to compensate for the loss in target volume coverage. The dosimetric parameters for the heart and lung and the target volume between the three treatment types were compared.

RESULTS

Of the three plans, the HBE plan yielded the most significant reduction in the doses received by the heart and lung (heart Dmean: 5.1 Gy vs. 12.9 Gy vs. 4.0 Gy and lung Dmean: 11.4 Gy vs. 13.2 Gy vs. 10.5 Gy, for 3D-CRT, IMRT, and HBE, respectively). Target coverage with all three techniques was within the acceptable range (Dmean 51.0 Gy vs. 51.2 Gy vs. 50.6 Gy, for 3D-CRT, IMRT, and HBE, respectively).

CONCLUSIONS

The HBE plan effectively reduced the amount of radiation exposure to the heart and lung. It could be beneficial for patients who are vulnerable to radiation-related cardiac or pulmonary toxicities.

Cardiac-sparing radiation therapy using positioning breast shell for patients with left-sided breast cancer who are ineligible for breath-hold techniques

Purpose

Patients with left-sided breast cancer (LSBC) are at increased risk of cardiac morbidity from adjuvant breast radiation therapy (ABRT). Breath-hold (BH) techniques substantially reduce the radiation received by heart during radiation therapy for LSBC. However, a subset of patients with LSBC are ineligible for BH techniques due to an inability to breath-hold or because of other comorbidities. To reduce radiation to the heart, we routinely use a custom-made breast shell for the treatment of patients with LSBC who are ineligible for BH techniques. This study evaluates the dosimetric impact of using a breast shell for patients with LSBC undergoing ABRT.

Methods and materials

Sixteen consecutive patients with LSBC who failed BH and underwent ABRT using a breast shell during the period of 2014 to 2016 were identified. Treatment was planned using field-in-field tangents with a prescribed dose of 42.5 Gy in 16 fractions. Comparisons between plans with and without a shell were made for each patient using a paired t test to quantify the sparing of organs at risk (OARs) and target coverage.

Results

There was no statistically significant difference in the planning target volume of breast coverage. A statistically significant improvement was observed in sparing the heart, left ventricle (LV), and ipsilateral lung (P-value < .001). Plans with the shell spared OARs better than the no-shell plans with a mean dose of 2.15 Gy versus 5.15 Gy (58.2% reduction) to the heart, 3.27 Gy versus 9.00 Gy (63.7% reduction) to the LV, and 5.16 Gy versus 7.95 Gy (35% reduction) to the ipsilateral lung. The irradiated volumes of OARs for plans with and without shell are 13.3 cc versus 59.5 cc (77.6% reduction) for the heart, 6.2 cc versus 33.2 cc (81.2% reduction) for the LV, and 92.8 cc versus 162.5 cc (42.9% reduction) for the ipsilateral lung.

Conclusions

A positioning breast shell offers significant benefit in terms of sparing the heart for patients with LSBC who are ineligible for BH techniques. It also can be used as a simple cardiac-sparing alternative in centers without BH capability.

The risk of reoperative cardiac surgery in radiation-induced valvular disease

OBJECTIVE

Mediastinal radiation therapy (MRT) increases the risk for adverse outcomes after cardiac surgery and is not incorporated in the Society of Thoracic Surgeons (STS) risk algorithm. We aimed to quantify the surgical risk conferred by MRT in patients undergoing primary and reoperative valvular operations.

METHODS

A retrospective analysis of 261 consecutive patients with prior MRT who underwent valvular operations between January 2002 and May 2015. Short- and long-term outcomes were compared for STS predicted risk of mortality, surgery type, gender, year of surgery, and age-matched patients stratified by reoperative status.

RESULTS

Mean age was 62.6 ± 12.1 years and 174 (67%) were women. The majority had received MRT for Hodgkin lymphoma (48.2%) and breast cancer (36%). Overall, 214 (82%) were primary and 47 (18%) were reoperative procedures. Reoperation carried a higher operative mortality than primary cases (17% vs 3.7%; P = .003). Compared with the 836 nonradiated matches, operative mortality and observed-to-expected STS mortality ratios were higher in primary (3.8% [1.4] vs 0.8% [0.32]; P = .004) and reoperative (17% [3.35] vs 2.3% [0.45]; P = .001) patients with prior MRT. Cox proportional hazard modeling revealed that in patients with previous MRT, primary (hazard ratio, 2.24; 95% confidence interval, 1.73-2.91) and reoperative status (hazard ratio, 3.19; 95% confidence interval, 1.95-5.21) adversely affected long-term survival compared with nonradiated matches.

CONCLUSIONS

Surgery for radiation-induced valvular heart disease has a higher operative mortality than predicted by STS predicted risk of mortality. Reoperations are associated with increased morbidity and mortality compared with primary cases. Careful patient selection is paramount and expanded indications for transcatheter therapies should be considered, especially in reoperative patients.

Long-Term Cardiovascular Risk After Radiotherapy in Women With Breast Cancer

Background

Radiotherapy for breast cancer often involves some incidental exposure of the heart to ionizing radiation. The effect of this exposure on the subsequent risk of heart disease is uncertain. We performed a meta‐analysis to investigate the link between radiotherapy and long‐term cardiovascular morbidity and mortality in patients with breast cancer.

Methods and Results

We performed a literature search using MEDLINE (January 1966 to January 2015) and EMBASE (January 1980 to January 2015) with no restrictions. Studies that reported relative risk (RR) estimates with 95%CIs for the associations of interest were included. Pooled effect estimates were obtained by using random‐effects meta‐analysis. Thirty‐nine studies involving 1 191 371 participants were identified. Patients who received left‐sided radiotherapy, as compared with those receiving right‐sided radiotherapy, experienced increased risks of developing coronary heart disease (RR 1.29, 95%CI 1.13‐1.48), cardiac death (RR 1.22, 95%CI 1.08‐1.37) and death from any cause (RR 1.05, 95%CI 1.01‐1.10). In a comparison of patients with radiotherapy and without radiotherapy, the RRs were 1.30 (95%CI 1.13‐1.49) for coronary heart disease and 1.38 (95%CI 1.18‐1.62) for cardiac mortality. Radiotherapy for breast cancer was associated with an absolute risk increase of 76.4 (95%CI 36.8‐130.5) cases of coronary heart disease and 125.5 (95%CI 98.8‐157.9) cases of cardiac death per 100 000 person‐years. The risk started to increase within the first decade for coronary heart disease and from the second decade for cardiac mortality.

Conclusions

Exposure of the heart to ionizing radiation during radiotherapy for breast cancer increases the subsequent risk of coronary heart disease and cardiac mortality.

Effect of accurate heart delineation on cardiac dose during the CONVERT trial

OBJECTIVE

This study investigated the effect of deviation from protocol in heart delineation for the Concurrent Once-daily Versus twice-daily Radiotherapy (CONVERT) Trial ( ClinicalTrials.gov Identifier NCT00433563) quality assurance (QA) programme and the effect of that on mean cardiac dose and percentage of heart volume receiving ≥5 Gy (V5%) and percentage of heart volume receiving ≥30 Gy (V30%).

METHODS

Patients with limited-stage small-cell lung cancer in the CONVERT trial were randomized to receive 45 Gy in 30# twice daily or 66 Gy in 33# once daily radiotherapy, with concurrent chemotherapy in both arms. Of the 100 trial patient cases reviewed by the QA team [for patient selection, disease/organs at risk (OARs) outlining and treatment planning], 50 patient cases were selected, and the heart was reoutlined according to the "gold standard" trial protocol. Dose-volume histogram (DVH) data were extracted. The impact of change in heart volume on cardiac DVH is presented.

RESULTS

For gold standard cardiac outlines, an increase in V5% and V30% was seen in 77.3% and 81.8% of cases, respectively, in the control arm (45 Gy) and in 78.6% and 82.1% of cases, respectively, in the experimental arm (66 Gy). The median increase in V5% was 1.4% and in V30%, it was 3.4%. The average of the mean cardiac dose for the control arm increased by 2.1 Gy (from 15.2 Gy for the centres outline to 17.3 Gy for the gold standard outline) and for the experimental arm by 2.4 Gy (from 16.2 to 18.6 Gy).

CONCLUSION

This study demonstrates the importance of having a robust QA programme in place to ensure accuracy of cardiac delineation to facilitate future studies investigating the impact of cardiac dose on toxicity. Advances in knowledge: This study highlights the importance of ensuring accurate delineation of OARs in clinical trials, where conclusions about normal tissue toxicity are to be drawn.

Cardiovascular Disease Mortality Among Breast Cancer Survivors

BACKGROUND

Cardiovascular disease (CVD) is of increasing concern among breast cancer survivors. However, the burden of this comorbidity in this group relative to the general population, and its temporal pattern, remains unknown.

METHODS

We compared deaths due to CVD in a population-based sample of 1,413 women with incident breast cancer diagnosed in 1996-1997, and 1,411 age-matched women without breast cancer. Date and cause of death through December 31, 2009 were assessed through the national death index and covariate data was gathered through structured interviews and medical record abstraction. Hazard ratios (HR) and 95% confidence intervals were calculated using Cox regression for overall mortality (HR) and CVD-specific death (cause-specific HR). Subdistribution HRs for CVD death were estimated from the Fine-Gray model.

RESULTS

Risk of death was greater among breast cancer survivors compared with women without breast cancer (HR: 1.8 [1.5, 2.1]). An increase in CVD-related death among breast cancer survivors was evident only 7 years after diagnosis (years 0-7, cause-specific HR: 0.80 [0.53, 1.2], subdistribution HR: 0.59 [0.40, 0.87]); years 7+, cause-specific HR: 1.8 [1.3, 2.5], subdistribution HR: 1.9 [1.4, 2.7]; P interaction: 0.001). An increase in CVD-related mortality was observed among breast cancer survivors receiving chemotherapy.

CONCLUSIONS

Breast cancer survivors are at greater risk for CVD-related mortality compared with women without breast cancer and this increase in risk is manifested approximately 7 years after diagnosis. Efforts should be made to identify risk factors and interventions that can be employed during this brief window to reduce the excess burden of CVD in this vulnerable population.

Late Effects of Total-Body Gamma Irradiation on Cardiac Structure and Function in Male Rhesus Macaques

Heart disease is an increasingly recognized, serious late effect of radiation exposure, most notably among breast cancer and Hodgkin's disease survivors, as well as the Hiroshima and Nagasaki atomic bomb survivors. The purpose of this study was to evaluate the late effects of total-body irradiation (TBI) on cardiac morphology, function and selected circulating biomarkers in a well-established nonhuman primate model. For this study we used male rhesus macaques that were exposed to a single total-body dose of ionizing gamma radiation (6.5-8.4 Gy) 5.6-9.7 years earlier at ages ranging from ∼3-10 years old and a cohort of nonirradiated controls. Transthoracic echocardiography was performed annually for 3 years on 20 irradiated and 11 control animals. Myocardium was examined grossly and histologically, and myocardial fibrosis/collagen was assessed microscopically and by morphometric analysis of Masson's trichrome-stained sections. Serum/plasma from 27 irradiated and 13 control animals was evaluated for circulating biomarkers of cardiac damage [N-terminal pro B-type natriuretic protein (nt-proBNP) and troponin-I], inflammation (CRP, IL-6, MCP-1, sICAM) and microbial translocation [LPS-binding protein (LBP) and sCD14]. A higher prevalence of histological myocardial fibrosis was observed in the hearts obtained from the irradiated animals (9/14) relative to controls (0/3) (P = 0.04, χ(2)). Echocardiographically determined left ventricular end diastolic and systolic diameters were significantly smaller in irradiated animals (repeated measures ANOVA, P < 0.001 and P < 0.008, respectively). Histomorphometric analysis of trichrome-stained sections of heart tissue demonstrated ∼14.9 ± 1.4% (mean ± SEM) of myocardial area staining for collagen in irradiated animals compared to 9.1 ± 0.9 % in control animals. Circulating levels of MCP-1 and LBP were significantly higher in irradiated animals (P < 0.05). A high incidence of diabetes in the irradiated animals was associated with higher plasma triglyceride and lower HDLc but did not appear to be associated with cardiovascular phenotypes. These results demonstrate that single total-body doses of 6.5-8.4 Gy produced long-term effects including a high incidence of myocardial fibrosis, reduced left ventricular diameter and elevated systemic inflammation. Additional prospective studies are required to define the time course and mechanisms underlying radiation-induced heart disease in this model.

Cardiovascular Late Effects and Exercise Treatment in Breast Cancer: Current Evidence and Future Directions

Advances in detection and supportive care strategies have led to improvements in cancer-specific and overall survival after a diagnosis of early-stage breast cancer. These improvements, however, are associated with an increase in competing forms of morbidity and mortality, particularly cardiovascular disease (CVD). Indeed, in certain subpopulations of patients, CVD is the leading cause of mortality after early breast cancer, and these women also have an increased risk of CVD-specific morbidity, including an elevated incidence of coronary artery disease and heart failure compared with their sex- and age-matched counterparts. Exercise treatment is established as the cornerstone of primary and secondary prevention of CVD in multiple clinical populations. The potential benefits of exercise treatment to modulate CVD or CVD risk factors before, immediately after, or in the months/years after adjuvant therapy for early-stage breast cancer have received limited attention. We discuss the risk and extent of CVD in patients with breast cancer, review the pathogenesis of CVD, and highlight existing evidence from select clinical trials investigating the efficacy of structured exercise treatment across the CVD continuum in early breast cancer.

Limitations of N-Terminal Pro-B-Type Natriuretic Peptide in the Diagnosis of Heart Disease among Cancer Patients Who Present with Cardiac or Pulmonary Symptoms

OBJECTIVES

Recognizing heart disease is relevant to oncologists because cancer patients are at an increased risk of cardiac mortality due to shared risk factors and the adverse effects of cancer therapy. This study assessed the extent to which the measurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP) aids in the diagnosis of heart disease in addition to a history of coronary artery disease and the presence of atrial fibrillation (composite test). The NT- proBNP cutoff value was 100 pg/ml.

METHODS

A series of 583 consecutive cancer patients (68.4 ± 11.0 years) who were referred because of cardiac or pulmonary symptoms prospectively underwent a diagnostic work-up. Heart disease was diagnosed if at least one of the following conditions was present: (a) history of coronary artery disease, (b) atrial fibrillation, (c) impaired left ventricular systolic function, (d) significant valvular disease, (e) pulmonary hypertension, or (f) left ventricular hypertrophy.

RESULTS

Except for (a), all 6 conditions were associated with NT-proBNP >100 pg/ml. The sensitivity/specificity values of the composite test were 0.92/0.50 for any heart disease. Several extracardiac covariates were associated with NT-proBNP >100 pg/ml, which contributed to the low test specificity.

CONCLUSIONS

The low specificity of NT-proBNP limits its value for the diagnosis of heart disease in cancer patients.

Internal Mammary and Medial Supraclavicular Irradiation in Breast Cancer

BACKGROUND

The effect of internal mammary and medial supraclavicular lymph-node irradiation (regional nodal irradiation) added to whole-breast or thoracic-wall irradiation after surgery on survival among women with early-stage breast cancer is unknown.

METHODS

We randomly assigned women who had a centrally or medially located primary tumor, irrespective of axillary involvement, or an externally located tumor with axillary involvement to undergo either whole-breast or thoracic-wall irradiation in addition to regional nodal irradiation (nodal-irradiation group) or whole-breast or thoracic-wall irradiation alone (control group). The primary end point was overall survival. Secondary end points were the rates of disease-free survival, survival free from distant disease, and death from breast cancer.

RESULTS

Between 1996 and 2004, a total of 4004 patients underwent randomization. The majority of patients (76.1%) underwent breast-conserving surgery. After mastectomy, 73.4% of the patients in both groups underwent chest-wall irradiation. Nearly all patients with node-positive disease (99.0%) and 66.3% of patients with node-negative disease received adjuvant systemic treatment. At a median follow-up of 10.9 years, 811 patients had died. At 10 years, overall survival was 82.3% in the nodal-irradiation group and 80.7% in the control group (hazard ratio for death with nodal irradiation, 0.87; 95% confidence interval [CI], 0.76 to 1.00; P=0.06). The rate of disease-free survival was 72.1% in the nodal-irradiation group and 69.1% in the control group (hazard ratio for disease progression or death, 0.89; 95% CI, 0.80 to 1.00; P=0.04), the rate of distant disease-free survival was 78.0% versus 75.0% (hazard ratio, 0.86; 95% CI, 0.76 to 0.98; P=0.02), and breast-cancer mortality was 12.5% versus 14.4% (hazard ratio, 0.82; 95% CI, 0.70 to 0.97; P=0.02). Acute side effects of regional nodal irradiation were modest.

CONCLUSIONS

In patients with early-stage breast cancer, irradiation of the regional nodes had a marginal effect on overall survival. Disease-free survival and distant disease-free survival were improved, and breast-cancer mortality was reduced. (Funded by Fonds Cancer; ClinicalTrials.gov number, NCT00002851.).

A higher incidence rate of acute coronary syndrome following radiation therapy in patients with breast cancer and a history of coronary artery diseases

This study aims to investigate whether patients with breast cancer and a history of cardiovascular diseases (CADs) are at an increased incidence of acute coronary syndrome (ACS) after receiving radiation therapy (RT). In Taiwan, 5828 patients who had a history of CAD were newly diagnosed of breast cancer and received mastectomy between 1999 and 2009. Among these patients, 1851 also received RT. The study cohort was prospectively followed to the end of 2010 for estimating the incidence of ACS in association with exposure to RT. A Cox proportional hazard model that was adjusted for covariates was used to estimate the hazard ratio (HR) of ACS. Over the study period, the incident rates of ACS for RT and control patients were estimated at 1.51 and 1.77 per 100 person-years, respectively. Covariate-adjusted regression analysis indicated that the hazard of ACS significantly increased in RT patients at an adjusted HR of 1.48 [95% confidence interval (CI) 1.18-1.87]. Both hypertension and diabetes significantly increased the hazard of ACS in this patient cohort, with adjusted HRs of 3.31 (95% CI 1.94-5.66) and 1.50 (95% CI 1.19-1.89), respectively. This 12-year follow-up study suggested excess of ACS events in association with RT exposure in patients with breast cancer who had a higher cardiovascular risk. In consideration of the benefit associated with RT, intensive cardiac care should be given to patients with breast cancer and high cardiovascular risk.

Mechanisms of cardiac radiation injury and potential preventive approaches

In addition to cytostatic treatment and surgery, the most common cancer treatment is gamma radiation. Despite sophisticated radiological techniques however, in addition to irradiation of the tumor, irradiation of the surrounding healthy tissue also takes place, which results in various side-effects, depending on the absorbed dose of radiation. Radiation either damages the cell DNA directly, or indirectly via the formation of oxygen radicals that in addition to the DNA damage, react with all cell organelles and interfere with their molecular mechanisms. The main features of radiation injury besides DNA damage is inflammation and increased expression of pro-inflammatory genes and cytokines. Endothelial damage and dysfunction of capillaries and small blood vessels plays a particularly important role in radiation injury. This review is focused on summarizing the currently available data concerning the mechanisms of radiation injury, as well as the effectiveness of various antioxidants, anti-inflammatory cytokines, and cytoprotective substances that may be utilized in preventing, mitigating, or treating the toxic effects of ionizing radiation on the heart.

A novel technique for image-guided local heart irradiation in the rat

In radiotherapy treatment of thoracic, breast and chest wall tumors, the heart may be included (partially or fully) in the radiation field. As a result, patients may develop radiation-induced heart disease (RIHD) several years after exposure to radiation. There are few methods available to prevent or reverse RIHD and the biological mechanisms remain poorly understood. In order to further study the effects of radiation on the heart, we developed a model of local heart irradiation in rats using an image-guided small animal conformal radiation therapy device (SACRTD) developed at our institution. First, Monte Carlo based simulations were used to design an appropriate collimator. EBT-2 films were used to measure relative dosimetry, and the absolute dose rate at the isocenter was measured using the AAPM protocol TG-61. The hearts of adult male Sprague-Dawley rats were irradiated with a total dose of 21 Gy. For this purpose, rats were anesthetized with isoflurane and placed in a custom-made vertical rat holder. Each heart was irradiated with a 3-beam technique (one AP field and 2 lateral fields), with each beam delivering 7 Gy. For each field, the heart was visualized with a digital flat panel X-ray imager and placed at the isocenter of the 1.8 cm diameter beam. In biological analysis of radiation exposure, immunohistochemistry showed γH2Ax foci and nitrotyrosine throughout the irradiated hearts but not in the lungs. Long-term follow-up of animals revealed histopathological manifestations of RIHD, including myocardial degeneration and fibrosis. The results demonstrate that the rat heart irradiation technique using the SACRTD was successful and that surrounding untargeted tissues were spared, making this approach a powerful tool for in vivo radiobiological studies of RIHD. Functional and structural changes in the rat heart after local irradiation are ongoing.

Serum biomarkers for the detection of cardiac toxicity after chemotherapy and radiation therapy in breast cancer patients

Multi-modality cancer treatments that include chemotherapy, radiation therapy, and targeted agents are highly effective therapies. Their use, especially in combination, is limited by the risk of significant cardiac toxicity. The current paradigm for minimizing cardiac morbidity, based on serial cardiac function monitoring, is suboptimal. An alternative approach based on biomarker testing, has emerged as a promising adjunct and a potential substitute to routine echocardiography. Biomarkers, most prominently cardiac troponins and natriuretic peptides, have been evaluated for their ability to describe the risk of potential cardiac dysfunction in clinically asymptomatic patients. Early rises in cardiac troponin concentrations have consistently predicted the risk and severity of significant cardiac events in patients treated with anthracycline-based chemotherapy. Biomarkers represent a novel, efficient, and robust clinical decision tool for the management of cancer therapy-induced cardiotoxicity. This article aims to review the clinical evidence that supports the use of established biomarkers such as cardiac troponins and natriuretic peptides, as well as emerging data on proposed biomarkers.

Quantifying intra- and inter-fractional motion in breast radiotherapy

Introduction

The magnitude of intra- and inter-fractional variation in the set up of breast cancer patients treated with tangential megavoltage photon beams was investigated using an electronic portal imaging device (EPID).

Methods

Daily cine-EPID images were captured during delivery of the tangential fields for ten breast cancer patients treated in the supine position. Measurements collected from each image included the central lung distance (CLD), central flash distance (CFD), superior axial measurement (SAM) and the inferior axial measurement (IAM). The variation of motion within a fraction (intra-fraction) and the variation between fractions (inter-fraction) was analysed to quantify set up variation and motion due to respiration.

Results

Altogether 3775 EPID images were collected from 10 patients. The effect of respiratory motion during treatment was <0.1 cm standard deviation (SD) in the anterior–posterior (AP) direction. The inter-fraction movement caused by variations in daily set up was larger at 0.28 cm SD in the AP direction. Superior–inferior (SI) variation was more difficult to summarise and proved unreliable as the measurements were taken to an ambiguous point on the images. It was difficult to discern true SI movement from that implicated by AP movement.

Conclusion

There is minimal intra-fractional chest wall motion due to respiration during treatment. Inter-fractional variation was larger, however, on average it remained within departmental tolerance (0.5 cm) for set up variations. This review of our current breast technique provides confidence in the feasibility of utilising advanced treatment techniques (field-in-field, intensity modulated radiotherapy or volumetric modulated arc therapy) following a review of the current imaging protocol.

Cancer in heart disease patients: what are the limitations in the treatment strategy?

Cardiovascular disease and cancer are leading causes of morbidity and mortality, and can both be present in one patient. In patients with simultaneous disease, the most threatening disease should be treated first. This is usually heart disease, but this can pose specific problems. If percutaneous coronary intervention is preferred, bleeding and thrombotic tendencies have to be taken into account in the subsequent treatment of the malignancy. With coronary artery bypass grafting, the advantages and disadvantages of one- or two-stage procedures, and the use of extracorporeal circulation have to be balanced. Development of heart disease after treatment of malignancy could be due to radiotherapy and chemotherapy. The effects of these cancer treatments have to be taken into account for the treatment options of the heart disease and the postoperative prognosis.

Late effects of local irradiation on the expression of inflammatory markers in the Arteria saphena of C57BL/6 wild-type and ApoE-knockout mice

Combined action of irradiation (IR), shear stress, and high blood pressure is well recognized to induce damage to vasculature, while data on pathological effects of IR in large peripheral vessels with low blood pressure are scarce. The purpose of the present study was hence to investigate time- and dose-dependent effects of local IR on inflammatory and prothrombotic processes in the Arteria (A.) saphena of C57BL/6 wild-type and apolipoprotein E (ApoE)-knockout mice. Single doses of 2, 5, 8, 10, or 16 Gy were locally delivered to the A. saphena of the left leg of the animals. The expression of CD31, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, monocyte chemoattractant protein-1 (MCP-1), and thrombomodulin (TM) was quantified by semiautomatic TissueFax fluorescence analysis in frozen arterial sections. Follow-up periods were 3, 6, 9, 12, or 18 months. Protein expression in the arterial wall displayed dose-dependent changes. Proinflammatory reactions were observed for CD31, E-selectin, ICAM, and VCAM already at doses of 2 Gy. Anti-inflammatory changes were detected for MCP-1 and TM. The effects were more pronounced in wild-type versus ApoE(-/-) mice. Changes remain mostly transient up to 16 Gy. Dose- and time-dependent changes in inflammatory and thrombotic mediators in the wall of the A. saphena were found after local IR but did not transform into histopathological consequences.

Cardiotoxicity and cancer therapy: treatment-related cardiac morbidity in patients presenting with symptoms suggestive of heart or lung disease

OBJECTIVES

Cardiac injury is one of the complications of cancer treatment. This study aimed to investigate the relationships between the types of radiotherapy of the chest (RT), chemotherapy (CT), cancer surgery (CS) and endocrine therapy (ET), and the presence of heart disease, and their associations with the serum level of N-terminal pro-B-type natriuretic peptide (NT-proBNP).

METHODS

A consecutive series of 374 patients with cancer who were referred because of symptoms suggestive of heart or lung disease prospectively underwent a diagnostic workup.

RESULTS

The prevalence of heart disease was 36.9%. RT administered before 1995 (n = 19) was associated with both increased odds of heart disease [adjusted odds ratio 10.3, 95% confidence interval 3.1-34.0] and higher ln-transformed NT-proBNP values (p < 0.01) compared to the control group (no RT or RT for right-sided breast cancer from 1995 onwards; n = 311). Anthracycline-treated patients (n = 54) had higher adjusted values for ln(NT-proBNP) compared to the control group (no CT; n = 243; p < 0.01) but no increased odds of heart disease.

CONCLUSIONS

While pre-1995 RT and anthracycline-containing CT were associated with cardiac effects, there was no evidence that RT using modern cardioprotective techniques, CT in the absence of anthracyclines, CS or ET had detrimental effects on the heart.

Understanding radiation-induced cardiovascular damage and strategies for intervention

There is a clear association between therapeutic doses of thoracic irradiation and an increased risk of cardiovascular disease (CVD) in cancer survivors, although these effects may take decades to become symptomatic. Long-term survivors of Hodgkin's lymphoma and childhood cancers have two-fold to more than seven-fold increased risks for late cardiac deaths after total tumour doses of 30-40 Gy, given in 2 Gy fractions, where large volumes of heart were included in the field. Increased cardiac mortality is also seen in women irradiated for breast cancer. Breast doses are generally 40-50 Gy in 2 Gy fractions, but only a small part of the heart is included in the treatment fields and mean heart doses rarely exceeded 10-15 Gy, even with older techniques. The relative risks of cardiac mortality (1.1-1.4) are consequently lower than for Hodgkin's lymphoma survivors. Some epidemiological studies show increased risks of cardiac death after accidental or environmental total body exposures to much lower radiation doses. The mechanisms whereby these cardiac effects occur are not fully understood and different mechanisms are probably involved after high therapeutic doses to the heart, or part of the heart, than after low total body exposures. These various mechanisms probably result in different cardiac pathologies, e.g. coronary artery atherosclerosis leading to myocardial infarct, versus microvascular damage and fibrosis leading to congestive heart failure. Experimental studies can help to unravel some of these mechanisms and may identify suitable strategies for managing or inhibiting CVD. In this overview, the main epidemiological and clinical evidence for radiation-induced CVD is summarised. Experimental data shedding light on some of the underlying pathologies and possible targets for intervention are also discussed.