Radiotherapy-induced heart disease: a review of the literature

Cardiac radiotherapy transiently alters left ventricular electrical properties and induces cardiomyocyte-specific ventricular substrate changes in heart failure

AIMS

Ongoing clinical trials investigate the therapeutic value of stereotactic cardiac radioablation (cRA) in heart failure patients with ventricular tachycardia. Animal data indicate an effect on local cardiac conduction properties. However, the exact mechanism of cRA in patients remains elusive. Aim of the current study was to investigate in vivo and in vitro myocardial properties in heart failure and ventricular tachycardia upon cRA.

METHODS AND RESULTS

High-density 3D electroanatomic mapping in sinus rhythm was performed in a patient with a left ventricular assist device and repeated ventricular tachycardia episodes upon several catheter-based endocardial radio-frequency ablation attempts. Subsequent to electroanatomic mapping and cRA of the left ventricular septum, two additional high-density electroanatomic maps were obtained at 2- and 4-month post-cRA. Myocardial tissue samples were collected from the left ventricular septum during 4-month post-cRA from the irradiated and borderzone regions. In addition, we performed molecular biology and mitochondrial density measurements of tissue and isolated cardiomyocytes. Local voltage was altered in the irradiated region of the left ventricular septum during follow-up. No change of local voltage was observed in the control (i.e. borderzone) region upon irradiation. Interestingly, local activation time was significantly shortened upon irradiation (2-month post-cRA), a process that was reversible (4-month post-cRA). Molecular biology unveiled an increased expression of voltage-dependent sodium channels in the irradiated region as compared with the borderzone, while Connexin43 and transforming growth factor beta were unchanged (4-month post-cRA). Moreover, mitochondrial density was decreased in the irradiated region as compared with the borderzone.

CONCLUSION

Our study supports the notion of transiently altered cardiac conduction potentially related to structural and functional cellular changes as an underlying mechanism of cRA in patients with ventricular tachycardia.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Optimal radiotherapy modality sparing for cardiac valves in left-sided breast cancer

Background

The cardiotoxicity caused by radiotherapy is a critical problem in the treatment of patients with breast cancer. The appropriate radiotherapy modality sparing for cardiac valves in left-sided breast cancer has not been well defined. The aim of this study was thus to compare the dosimetric differences in heart and cardiac valves of 3-dimensional conformal radiotherapy (3D-CRT), fixed-field intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) to find the optimal radiotherapy modality sparing for cardiac valves in patients with left breast cancer.

Methods

From January 5, 2021, to March 15, 2021, 21 patients with left-sided breast cancer postmastectomy were included in this study, and 3 different plans for adjuvant radiation were created using 3D-CRT, IMRT, and VMAT for each patient. All patients received 50 Gy in 25 fractions. The mean dose (D_mean) of the heart; percentage volume of the heart receiving ≥5 Gy (V₅), ≥30 Gy (V₃₀), and ≥40 Gy (V₄₀); and the D_mean and the near-maximum dose (D_0.03cc) of cardiac valves were extracted from dose-volume histograms (DVHs) and compared. The correlations in dosimetric factors between cardiac valves and the whole heart were analyzed.

Results

IMRT significantly decreased the values of V₅, V₃₀, V₄₀, and D_mean in the whole heart compared to 3D-CRT and VMAT (P<0.001). Among the 3 different plans, IMRT had the lowest radiation dose to the D_mean and the D_0.03cc of the aortic valve (1.27 Gy/1.75 Gy), pulmonary valve (3.44 Gy/6.89 Gy), tricuspid valve (1.02 Gy/1.14 Gy), and mitral valve (0.93 Gy/1.00 Gy). Pearson correlation analysis found that local parameters (D_mean and D_0.03cc) within valves were strongly correlated to the global parameters (V₅, V₃₀, V₄₀, and D_mean) of the heart.

Conclusions

This study revealed that IMRT showed the lowest cardiac valves dose compared with 3D-CRT and VMAT in left-sided breast cancer radiotherapy. IMRT might be the optimal modality sparing for cardiac valves in this group of patients. Further studies need to be carried out in order to validate the protective role of IMRT on the cardiac valves.

Case report: Early acute myocarditis after radiation therapy for breast cancer: A case presentation and review of literature

Breast cancer is the most commonly diagnosed cancer in women worldwide, and with the increased survival of patients by novel treatments, the frequency of complications of cancer treatments rises. Radiotherapy, especially on the chest wall, can damage different cardiac structures. Radiotherapy-induced cardiomyopathy mainly occurs over 10 years after breast cancer treatment; however, there is a gap in the literature on acute myocarditis following radiotherapy. Here, we present a 54-year-old woman who developed acute myocarditis shortly after 25 sessions of radiotherapy with 50 Gy of radiation, successfully diagnosed with the use of speckle tracking echocardiography (STE) and cardiac magnetic resonance (CMR), and responded to the medical treatment with relative clinical improvement until the final follow-up. This case suggests the necessity of detailed examination of patients after radiotherapy, not only for chronic occurrence of cardiomyopathy but also for acute myocarditis. Although STE and CMR resulted in accurate diagnosis, in this case, further studies are required to determine the diagnostic accuracy of these two imaging methods compared with other imaging modalities in such patients and investigate the best diagnostic tool and therapeutic approach for these patients.

The Lymphatic Endothelium in the Context of Radioimmuno-Oncology

The study of lymphatic tumor vasculature has been gaining interest in the context of cancer immunotherapy. These vessels constitute conduits for immune cells' transit toward the lymph nodes, and they endow tumors with routes to metastasize to the lymph nodes and, from them, toward distant sites. In addition, this vasculature participates in the modulation of the immune response directly through the interaction with tumor-infiltrating leukocytes and indirectly through the secretion of cytokines and chemokines that attract leukocytes and tumor cells. Radiotherapy constitutes the therapeutic option for more than 50% of solid tumors. Besides impacting transformed cells, RT affects stromal cells such as endothelial and immune cells. Mature lymphatic endothelial cells are resistant to RT, but we do not know to what extent RT may affect tumor-aberrant lymphatics. RT compromises lymphatic integrity and functionality, and it is a risk factor to the onset of lymphedema, a condition characterized by deficient lymphatic drainage and compromised tissue homeostasis. This review aims to provide evidence of RT's effects on tumor vessels, particularly on lymphatic endothelial cell physiology and immune properties. We will also explore the therapeutic options available so far to modulate signaling through lymphatic endothelial cell receptors and their repercussions on tumor immune cells in the context of cancer. There is a need for careful consideration of the RT dosage to come to terms with the participation of the lymphatic vasculature in anti-tumor response. Here, we provide new approaches to enhance the contribution of the lymphatic endothelium to radioimmuno-oncology.

MiRNA-Mediated Fibrosis in the Out-of-Target Heart following Partial-Body Irradiation

Recent reports have shown a link between radiation exposure and non-cancer diseases such as radiation-induced heart disease (RIHD). Radiation exposures are often inhomogeneous, and out-of-target effects have been studied in terms of cancer risk, but very few studies have been carried out for non-cancer diseases. Here, the role of miRNAs in the pathogenesis of RIHD was investigated. C57Bl/6J female mice were whole- (WBI) or partial-body-irradiated (PBI) with 2 Gy of X-rays or sham-irradiated (SI). In PBI exposure, the lower third of the mouse body was irradiated, while the upper two-thirds were shielded. From all groups, hearts were collected 15 days or 6 months post-irradiation. The MiRNome analysis at 15 days post-irradiation showed that miRNAs, belonging to the myomiR family, were highly differentially expressed in WBI and PBI mouse hearts compared with SI hearts. Raman spectral data collected 15 days and 6 months post-irradiation showed biochemical differences among SI, WBI and PBI mouse hearts. Fibrosis in WBI and PBI mouse hearts, indicated by the increased deposition of collagen and the overexpression of genes involved in myofibroblast activation, was found 6 months post-irradiation. Using an in vitro co-culture system, involving directly irradiated skeletal muscle and unirradiated ventricular cardiac human cells, we propose the role of miR-1/133a as mediators of the abscopal response, suggesting that miRNA-based strategies could be relevant for limiting tissue-dependent reactions in non-directly irradiated tissues.

Prevalence of Cardiovascular Disease in Patients With Potentially Curable Malignancies

Background

Although a common challenge for patients and clinicians, there is little population-level evidence on the prevalence of cardiovascular disease (CVD) in individuals diagnosed with potentially curable cancer.

Objectives

We investigated CVD rates in patients with common potentially curable malignancies and evaluated the associations between patient and disease characteristics and CVD prevalence.

Methods

The study included cancer registry patients diagnosed in England with stage I to III breast cancer, stage I to III colon or rectal cancer, stage I to III prostate cancer, stage I to IIIA non-small-cell lung cancer, stage I to IV diffuse large B-cell lymphoma, and stage I to IV Hodgkin lymphoma from 2013 to 2018. Linked hospital records and national CVD databases were used to identify CVD. The rates of CVD were investigated according to tumor type, and associations between patient and disease characteristics and CVD prevalence were determined.

Results

Among the 634,240 patients included, 102,834 (16.2%) had prior CVD. Men, older patients, and those living in deprived areas had higher CVD rates. Prevalence was highest for non-small-cell lung cancer (36.1%) and lowest for breast cancer (7.7%). After adjustment for age, sex, the income domain of the Index of Multiple Deprivation, and Charlson comorbidity index, CVD remained higher in other tumor types compared to breast cancer patients.

Conclusions

There is a significant overlap between cancer and CVD burden. It is essential to consider CVD when evaluating national and international treatment patterns and cancer outcomes.

Detection of Subclinical Cardiovascular Disease by Cardiovascular Magnetic Resonance in Lymphoma Survivors

BACKGROUND

Long-term survivors of Hodgkin lymphoma (HL) and mediastinal non-Hodgkin lymphoma experience late adverse effects of radiotherapy and/or anthracycline-containing chemotherapy, leading to premature cardiovascular morbidity and mortality.

OBJECTIVES

The aim of this study was to identify markers for subclinical cardiovascular disease using cardiovascular magnetic resonance (CMR) in survivors of HL and non-Hodgkin lymphoma.

METHODS

CMR was performed in 80 lymphoma survivors treated with mediastinal radiotherapy with or without anthracyclines, and results were compared with those among 40 healthy control subjects matched for age and sex.

RESULTS

Of the 80 lymphoma survivors, 98% had histories of HL, the mean age was 47 ± 11 years, and 54% were male. Median radiotherapy dose was 36 Gy (interquartile range: 36-40 Gy), and radiotherapy was combined with anthracyclines in 70 lymphoma survivors (88%). Mean time between diagnosis and CMR was 20 ± 8 years. Significantly lower left ventricular (LV) ejection fraction (53% ± 5% vs 60% ± 5%; P < 0.001) and LV mass (47 ± 10 g/m2 vs 56 ± 8 g/m2; P < 0.001) and higher LV end-systolic volume (37 ± 8 mL/m2 vs 33 ± 7 mL/m2; P = 0.013) were found in lymphoma survivors. LV global strain parameters were also significantly worse in lymphoma survivors (P < 0.02 for all). Native myocardial T1 was significantly higher in lymphoma survivors compared with healthy control subjects (980 ± 33 ms vs 964 ± 25 ms; P = 0.007), and late gadolinium enhancement was present in 11% of the survivors.

CONCLUSIONS

Long-term lymphoma survivors have detectable changes in LV function and native myocardial T1 on CMR. Further longitudinal studies are needed to assess the implication of these changes in relation to treatment and clinical outcome.

When Manual Analysis of 12-Lead ECG Holter Plays a Critical Role in Discovering Unknown Patterns of Increased Arrhythmogenic Risk: A Case Report of a Patient Treated with Tamoxifen and Subsequent Pneumonia in COVID-19

Several medicines, including cancer therapies, are known to alter the electrophysiological function of ventricular myocytes resulting in abnormal prolongation and dispersion of ventricular repolarization (quantified by multi-lead QTc measurement). This effect could be amplified by other concomitant factors (e.g., combination with other drugs affecting the QT, and/or electrolyte abnormalities, such as especially hypokalemia, hypomagnesaemia, and hypocalcemia). Usually, this condition results in higher risk of torsade de point and other life-threatening arrhythmias, related to unrecognized unpaired cardiac ventricular repolarization reserve (VRR). Being VRR a dynamic phenomenon, QT prolongation might often not be identified during the 10-s standard 12-lead ECG recording at rest, leaving the patient at increased risk for life-threatening event. We report the case of a 49-year woman, undergoing tamoxifen therapy for breast cancer, which alteration of ventricular repolarization reserve, persisting also after correction of concomitant recurrent hypokalemia, was evidenced only after manual measurements of the corrected QT (QTc) interval from selected intervals of the 12-lead ECG Holter monitoring. This otherwise missed finding was fundamental to drive the discontinuation of tamoxifen, shifting to another "safer" therapeutic option, and to avoid the use of potentially arrhythmogenic antibiotics when treating a bilateral pneumonia in recent COVID-19.

The value of the tumour-stroma ratio for predicting neoadjuvant chemoradiotherapy response in locally advanced rectal cancer: a case control study

BACKGROUND

The tumour-stroma ratio (TSR) is recognized as a practical prognostic factor in colorectal cancer. However, TSR assessment generally utilizes surgical specimens. This study aims to investigate whether the TSR evaluated from preoperative biopsy specimens by a semi-automatic quantification method can predict the response after neoadjuvant chemoradiotherapy (nCRT) of patients with locally advanced rectal cancer (LARC).

METHODS

A total of 248 consecutive patients diagnosed with LARC and treated with nCRT followed by resection were included. Haematoxylin and eosin (HE)-stained sections of biopsy specimens were collected, and the TSR was evaluated by a semi-automatic quantification method and was divided into three categories, using the cut-offs determined in the whole cohort to balance the proportion of patients in each category. The response to nCRT was evaluated on the primary tumour resection specimen by an expert pathologist using the four-tier tumour regression grade (TRG) system.

RESULTS

The TSR can discriminate patients that are major-responders (TRG 0-1) from patients that are non-responders (TRG 2-3). Patients were divided into stroma-low (33.5%), stroma-intermediate (33.9%), and stroma-high (32.7%) groups using 56.3 and 72.8% as the cutoffs. In the stroma-low group, 58 (69.9%) patients were major-responders, and only 39 (48.1%) patients were considered major-responders in the stroma-high group (P = 0.018). Multivariate analysis showed that the TSR was the only pre-treatment predictor of response to nCRT (adjusted odds ratio 0.40, 95% confidence interval 0.21-0.76, P = 0.002).

CONCLUSION

An elevated TSR in preoperative biopsy specimens is an independent predictor of nCRT response in LARC. This semi-automatic quantified TSR could be easily translated into routine pathologic assessment due to its reproducibility and reliability.

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

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

Acquired Immunity Is Not Essential for Radiation-Induced Heart Dysfunction but Exerts a Complex Impact on Injury

While radiation therapy (RT) can improve cancer outcomes, it can lead to radiation-induced heart dysfunction (RIHD) in patients with thoracic tumors. This study examines the role of adaptive immune cells in RIHD. In Salt-Sensitive (SS) rats, image-guided whole-heart RT increased cardiac T-cell infiltration. We analyzed the functional requirement for these cells in RIHD using a genetic model of T- and B-cell deficiency (interleukin-2 receptor gamma chain knockout (IL2RG-/-)) and observed a complex role for these cells. Surprisingly, while IL2RG deficiency conferred protection from cardiac hypertrophy, it worsened heart function via echocardiogram three months after a large single RT dose, including increased end-systolic volume (ESV) and reduced ejection fraction (EF) and fractional shortening (FS) (p < 0.05). Fractionated RT, however, did not yield similarly increased injury. Our results indicate that T cells are not uniformly required for RIHD in this model, nor do they account for our previously reported differences in cardiac RT sensitivity between SS and SS.BN3 rats. The increasing use of immunotherapies in conjunction with traditional cancer treatments demands better models to study the interactions between immunity and RT for effective therapy. We present a model that reveals complex roles for adaptive immune cells in cardiac injury that vary depending on clinically relevant factors, including RT dose/fractionation, sex, and genetic background.