Coronary heart disease after mediastinal irradiation for Hodgkin's disease

All for one, though not one for all: team players in normal tissue radiobiology

PURPOSE

As part of the special issue on 'Women in Science', this review offers a perspective on past and ongoing work in the field of normal (non-cancer) tissue radiation biology, highlighting the work of many of the leading contributors to this field of research. We discuss some of the hypotheses that have guided investigations, with a focus on some of the critical organs considered dose-limiting with respect to radiation therapy, and speculate on where the field needs to go in the future.

CONCLUSIONS

The scope of work that makes up normal tissue radiation biology has and continues to play a pivotal role in the radiation sciences, ensuring the most effective application of radiation in imaging and therapy, as well as contributing to radiation protection efforts. However, despite the proven historical value of preclinical findings, recent decades have seen clinical practice move ahead with altered fractionation scheduling based on empirical observations, with little to no (or even negative) supporting scientific data. Given our current appreciation of the complexity of normal tissue radiation responses and their temporal variability, with tissue- and/or organ-specific mechanisms that include intra-, inter- and extracellular messaging, as well as contributions from systemic compartments, such as the immune system, the need to maintain a positive therapeutic ratio has never been more urgent. Importantly, mitigation and treatment strategies, whether for the clinic, emergency use following accidental or deliberate releases, or reducing occupational risk, will likely require multi-targeted approaches that involve both local and systemic intervention. From our personal perspective as five 'Women in Science', we would like to acknowledge and applaud the role that many female scientists have played in this field. We stand on the shoulders of those who have gone before, some of whom are fellow contributors to this special issue.

Dose to the cardio-pulmonary system and treatment-induced electrocardiogram abnormalities in locally advanced non-small cell lung cancer

•

ECG abnormalities after chemo-RT in LA-NSCLC are common (35%–67%).

•

Non-specific ECG abnormalities are associated with a high superior vena cava dose.

•

Reducing cardiopulmonary dose is likely to lead to less radiation-induced cardiac toxicity.

Introduction

High dose radiotherapy (RT) has been associated with unexpectedly short survival times for locally advanced Non-Small Cell Lung Cancer (LA-NSCLC) patients. Here we tested the hypothesis that cardiac substructure dose is associated with electrocardiography (ECG) assessed abnormalities after RT for LA-NSCLC.

Materials and methods

Pre- and post-RT ECGs were analyzed for 155 LA-NSCLC patients treated to a median of 64 Gy in 1.8–2.0 Gy fractions using intensity-modulated RT plus chemotherapy (concurrent/sequential: 64%/36%) between 2004 and 2014. ECG abnormalities were classified as new Arrhythmic, Ischemic/Pericardial, or Non-specific (A_ΔECG, I/P_ΔECG, or NS_ΔECG) events. Abnormalities were modeled as time to ECG events considering death a competing risk, and the variables considered for analysis were fractionation-corrected dose-volume metrics (α/β = 3 Gy) of ten cardio-pulmonary structures (aorta, heart, heart chambers, inferior and superior vena cava, lung, pulmonary artery) and 15 disease, patient and treatment characteristics. Each abnormality was modelled using bootstrapping and a candidate predictor was suggested by a median multiple testing-adjusted p-value ≤0.05 across the 1000 generated samples. Forward-stepwise multivariate analysis was conducted in case of more than one candidate.

Results

At a median of eight months post-RT, the rate of A_ΔECG, I/P_ΔECG, and NS_ΔECG was 66%, 35%, and 67%. Both A_ΔECG and I/P_ΔECG were associated with worse performance status (p = 0.007, 0.03), while a higher superior vena cava minimum dose was associated with NS_ΔECG (p = 0.002).

Conclusion

This study suggests that higher radiation doses to the cardio-pulmonary system lead to non-specific ECG abnormalities. Reducing dose to this system, along with effective tumor control, is likely to decrease radiation-induced cardiac toxicity.

Coronary Artery Stenosis following Mediastinal Radiation Therapy. Case Report and Review of the Literature

A case of coronary artery stenosis following mediastinal radiation therapy in a young woman and a review of the literature offer indications on the criteria to follow in the diagnosis of coronary artery disease secondary to mediastinal radiation therapy.

Radiation Matters of the Heart: A Mini Review

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

Radiation Therapy Induced Cardiovascular Disease

Contemporary treatment modalities for malignancy including radiation therapy have led to improved survival. However treatment related complications manifesting later in life including cardiovascular disease has led to survivors exhibiting a lower long term survival rate, when compared to age matched controls. This narrative review will discuss the pathophysiology, risk factors, clinical presentation, management and preventative techniques related to radiotherapy-induced cardiotoxicity.

Chronic Internal Exposure to Low Dose 137Cs Induces Positive Impact on the Stability of Atherosclerotic Plaques by Reducing Inflammation in ApoE-/- Mice

After Chernobyl and Fukushima Daï Chi, two major nuclear accidents, large amounts of radionuclides were released in the environment, mostly caesium 137 (137Cs). Populations living in contaminated territories are chronically exposed to radionuclides by ingestion of contaminated food. However, questions still remain regarding the effects of low dose ionizing radiation exposure on the development and progression of cardiovascular diseases. We therefore investigated the effects of a chronic internal exposure to 137Cs on atherosclerosis in predisposed ApoE-/- mice. Mice were exposed daily to 0, 4, 20 or 100 kBq/l 137Cs in drinking water, corresponding to range of concentrations found in contaminated territories, for 6 or 9 months. We evaluated plaque size and phenotype, inflammatory profile, and oxidative stress status in different experimental groups. Results did not show any differences in atherosclerosis progression between mice exposed to 137Cs and unexposed controls. However, 137Cs exposed mice developed more stable plaques with decreased macrophage content, associated with reduced aortic expression of pro-inflammatory factors (CRP, TNFα, MCP-1, IFNγ) and adhesion molecules (ICAM-1, VCAM-1 and E-selectin). Lesions of mice exposed to 137Cs were also characterized by enhanced collagen and smooth muscle cell content, concurrent with reduced matrix metalloproteinase MMP8 and MMP13 expression. These results suggest that low dose chronic exposure of 137Cs in ApoE-/- mice enhances atherosclerotic lesion stability by inhibiting pro-inflammatory cytokine and MMP production, resulting in collagen-rich plaques with greater smooth muscle cell and less macrophage content.

Vascular injury in cancer survivors

With an increase in the number of patients surviving many years following successful cancer treatment, has come an improved understanding of the long-term effects of cancer therapy and its implications on future health. Premature cardiovascular disease is a significant cause of early morbidity and the leading non-cancer cause of death in this population. Chemotherapeutic agents and radiation therapy are known to be cardiotoxic. However, numerous vascular-related toxicities have also been observed among cancer survivors, such as myocardial ischemia, transient ischemic attacks, and stroke, suggesting a degree of chronic endothelial injury and dysfunction leading to premature atherosclerotic disease. Vascular health in cancer survivors may be further compromised by metabolic abnormalities such as obesity, insulin resistance, and dyslipidemias which have also been reported following cancer therapy. Furthermore, some survivors experience gonadal dysfunction and loss of potentially protective sex steroids or undergo hormonal therapies that induce additional metabolic abnormalities. The effects of cancer therapies upon the endothelial monolayer have not been fully explored. An understanding of potential injury to and dysfunction of the circulatory system among cancer survivors is essential for identifying preventive strategies and therapeutic targets.

Coronary heart disease--a possible risk in megavoltage therapy?

A 21-year old man died of an extensive anteroseptal myocardial infarction 16 months after receiving megavoltage radiotherapy to a mantle field for Hodgkin's disease stage PS IA confined to the midcervical lymph nodes on the left side of the neck. Post mortem findings revealed severe atherosclerotic changes in the coronary arteries. This case and a review of the literature suggest that irradiation to the heart may induce or accelerate atherosclerosis of the epicardial vessels. This should be taken into consideration when starting prophylactic irradiation to the mantle field in patients with Hodgkin's disease stage IA without obvious involvement of the mediastinun. Histologic examination of the heart and coronary vessels should be performed in any fatal case after megavoltage therapy involving the heart.

Neoplasms involving the heart, their simulators, and adverse consequences of their therapy

Primary cardiac tumors involving the heart may be either benign or malignant. Most of the benign tumors are myxomas, which are most commonly located in the left atrium. Primary malignant neoplasms usually involve the myocardium and the interior of the cardiac cavities, whereas neoplasms metastatic to the heart most commonly involve pericardium, and pericardial effusion and constriction are the most common consequences. Computed tomography and magnetic resonance imaging are becoming the most useful instruments of precision for the diagnosis of cardiac tumors. Pericardial cysts, teratomas, lipomatous hypertrophy of the atrial septum, papillary fibroelastomas, thrombi, and sarcoid are frequently mistaken for cardiac neoplasms. There are a number of cardiac consequences of malignancy, including radiation heart disease, cardiac hemorrhages, cardiac infection, cardiac adiposity or the corticosteroid-treated heart, cardiac hemosiderosis, and toxicity due to anthracycline chemotherapy.

Acute myocardial infarction after bone marrow transplantation: an unsuspected late complication

Acute myocardial infarction is a common disease rarely seen as a complication of bone marrow transplantation in young patients. We report on a 25-year-old patient 3.5 years after bone marrow transplantation who suffered an acute anterior wall myocardial infarction complicated by cardiogenic shock. The patient was treated with thrombolysis and emergent coronary angioplasty but died a few hours following admission. We suggest that the combination of low-dose chest irradiation and prolonged immunosuppression with graft-versus-host disease contributed to the development of the coronary artery disease in this patient. Though rarely encountered, physicians caring for young patients after bone marrow transplantation should be aware of potential ischemic complications.

Radiation-associated cardiovascular disease

As the number of cancer survivors grows because of advances in therapy, it has become more important to understand the long-term complications of these treatments. This article presents the current knowledge of adverse cardiovascular effects of radiotherapy to the chest. Emphasis is on clinical presentations, recommendations for follow-up, and treatment of patients previously exposed to irradiation. Medline literature searches were performed, and abstracts related to this topic from oncology and cardiology meetings were reviewed. Potential adverse effects of mediastinal irradiation are numerous and can include coronary artery disease, pericarditis, cardiomyopathy, valvular disease and conduction abnormalities. Damage appears to be related to dose, volume and technique of chest irradiation. Effects may initially present as subclinical abnormalities on screening tests or as catastrophic clinical events. Estimates of relative risk of fatal cardiovascular events after mediastinal irradiation for Hodgkin's disease ranges between 2.2 and 7.2 and after irradiation for left-sided breast cancer from 1.0 to 2.2. Risk is life long, and absolute risk appears to increase with length of time since exposure. Radiation-associated cardiovascular toxicity may in fact be progressive. Long-term cardiac follow-up of these patients is therefore essential, and the range of appropriate cardiac screening is discussed, although no specific, evidence-based screening regimen was found in the literature.

Pathophysiological effects of radiation on atherosclerosis development and progression, and the incidence of cardiovascular complications

Radiation therapy while important in the management of several diseases, is implicated in the causation of atherosclerosis and other cardiovascular complications. Cancer and atherosclerosis go through the same stages of initiation, promotion, and complication, beginning with a mutation in a single cell. Clinical observations before the 1960s lead to the belief that the heart is relatively resistant to the doses of radiation used in radiotherapy. Subsequently, it was discovered that the heart is sensitive to radiation and many cardiac structures may be damaged by radiation exposure. A significantly higher risk of death due to ischemic heart disease has been reported for patients treated with radiation for Hodgkin's disease and breast cancer. Certain cytokines and growth factors, such as TGF-beta1 and IL-1 beta, may stimulate radiation-induced endothelial proliferation, fibroblast proliferation, collagen deposition, and fibrosis leading to advanced lesions of atherosclerosis. The treatment for radiation-induced ischemic heart disease includes conventional pharmacological therapy, balloon angioplasty, and bypass surgery. Endovascular irradiation has been shown to be effective in reducing restenosis-like response to balloon-catheter injury in animal models. Caution must be exercised when radiation therapy is combined with doxorubicin because there appears to be a synergistic toxic effect on the myocardium. Damage to endothelial cells is a central event in the pathogenesis of damage to the coronary arteries. Certain growth factors that interfere with the apoptotic pathway may provide new therapeutic strategies for reducing the risk of radiation-induced damage to the heart. Exposure to low level occupational or environmental radiation appears to pose no undue risk of atherosclerosis development or cardiovascular mortality. But, other radiation-induced processes such as the bystander effects, abscopal effects, hormesis, and individual variations in radiosensitivity may be important in certain circumstances.

Cardiac Neoplasms

Surgical resection is usually the only form of curative therapy available for primary cardiac neoplasms. Benign tumors can often be completely removed with few complications and a low mortality rate, but complete resection is possible for fewer than half of primary malignant tumors. Radiation therapy plays an adjunct and palliative role in treatment. The outcome of chemotherapy, the dominant treatment method, is poor. Sarcomas are inherently chemoresistant and show a response rate of less than 50%. Lymphomas present late and respond poorly. Cardiectomy and cardiac transplantation may cure unresectable benign cardiac tumors or, rarely, malignant ones.

Vasculopathy of small muscular arteries in pediatric patients after bone marrow transplantation

Bone Marrow Transplant (BMT) is a critical therapeutic intervention for a variety of diseases occurring in the pediatric patient. Complications of allogeneic BMT include graft-versus-host disease (GVHD), infection, drug toxicity, thrombotic microangiopathy, and veno-occlusive disease. With solid organ transplantation, chronic vascular rejection has emerged as a major factor limiting long-term survival of the graft. We present a vasculopathy of small muscular arteries in 6 patients after allogeneic BMT. Cases include 4 boys and 2 girls ranging in age from 4 months to 13 years with full or partial human leukocyte antigen matching. Five of the 6 transplants were from related donors. The vasculopathy occurred 13 to 418 days after transplant and was noted in surgical specimens (2) and at autopsy (4). It was seen in the gastrointestinal tract and lung in 3 cases each. Vascular changes in small muscular arteries include concentric intimal or medial hyperplasia with luminal narrowing, prominent myxoid change, extravasated red blood cells, and presence of some foamy histiocytes with no evidence of thrombotic microangiopathy. Vasculopathy contributed to intestinal compromise requiring surgical intervention 3 times in 1 patient, and diffuse alveolar damage with hemorrhage in another. All 6 patients are dead. The cause of this unusual vasculopathy present in patients after BMT is likely to be multifactorial, involving effects of irradiation, chemotherapy, cyclosporine, and GVHD. Together these may create a negative synergy which produces an obliterative arteriopathy that should be recognized as a pathological entity and may be a harbinger of a poor prognosis.

Endovascular brachytherapy--treatment planning and radiation protection

The risk of restenosis, main late effect limiting the success of percutaneous transluminal coronary artery angioplasty, can be reduced significantly by vascular radiotherapy, subsequent to PTCA. This discovery lead to the development of new irradiation techniques. Endovascular brachytherapy is the choice in treatment of coronary artery stenosis. Successful irradiation, however, requires precise treatment planning. This review addresses the physical possibilities and problems of intravascular brachytherapy planning, and the radiobiologically based definition of the target volume and of structures at risk. Recommendations for dose specification, recording and reporting are given. The criteria for selecting a vascular radiotherapy technique are discussed as well as the possibilities of dosimetric treatment planning and quality assurance based on precise plastic scintillator dosimetry and intravascular ultrasound. Radiation protection and safety must be reconsidered prior to the usage of therapeutic radiation sources in the catheter laboratory and for the decision about emergency plans. Finally, the design of clinical trials, the role of medical physicists, and the future of irradiation treatment of stenosis is discussed.

Surgical management of radiation-induced heart disease

BACKGROUND

With the increasing population of patients with prior mediastinal irradiation, cardiac surgeons will encounter patients with radiation-induced damage to the heart and the great vessels. Awareness of the pathology and the surgical management is essential to provide optimal care for these patients.

METHODS

Eight patients with radiation-induced heart disease were encountered in the last 10 years. After a brief clinical presentation, the surgical management of radiation-induced heart disease is reviewed.

RESULTS

Radiation can affect all the structures in the heart, including the coronary arteries, the valves, and the conduction system. The pericardium is the most commonly involved, and the conduction system is the least involved. Pericardiectomy is quite effective in patients with symptomatic pericardial effusion or constriction. The coronary lesions are located predominantly in the ostial or proximal regions of the epicardial vessels. Percutaneous transluminal coronary angioplasty alone appears to have a high rate of restenosis. Surgical revascularization has good long-term results, and the internal mammary artery should be used if it is satisfactory. The aortic and mitral valves are more commonly involved than the tricuspid and pulmonary valves. Myocardial dysfunction predominantly affects the right ventricle and requires particular attention during cardiopulmonary bypass and in the postoperative period. Restoration of sinus rhythm is essential in view of stiffness of the ventricles. Flexibility in the surgical approach with selective use of thoracotomy will facilitate the surgical procedure in certain patients.

CONCLUSIONS

Surgeons should be well versed in all the manifestations and the management of radiation-induced heart disease.

[Intravascular irradiation in the combined therapy and prevention of restenosis. Overview]

Despite numerous efforts in catheter technology and procedural approaches the problem of restenosis in interventional cardiology persists. Although the implantation of coronary stents has significantly reduced restenosis rates based on the inhibition of elastic recoil, intimal proliferation as the second major mechanism for postinterventional restenosis could not effectively be suppressed. Intimal proliferation is the response to vessel injury following interventional procedure, e.g. balloon angioplasty. It results in the adhesion of mono- and lymphocytes which themselves trigger the colonisation of myofibroblasts. Intracoronary irradiation seeks to prevent this proliferative process as it destroys or irreversibly alters DNA structures of cells at the site of balloon injury. The antiproliferative effect depends on the irradiation dosis, the timing and the cell cycle phase. Mainly beta- and gamma-radiation is used for intracoronary irradiation. Beta-emitters are characterized by a sharp decline of dose rate within millimeters from the actual source. The exposure to surrounding tissue as well the catheter staff can be kept to a minimum. The high intensity of beta-emitters allow a short treatment period of minutes to gain an effective radiation dose to the target. In contrast, gamma-emitters have a low radial dose distribution resulting in high dosage even centimeters away from the source. These emitters require additional shielding in the catheter laboratory and lead to excessive whole body doses. To achieve a sufficient dose in the target tissue, irradiation times of more than 20 minutes are necessary which prolongs the interventional procedure substantially. At present, catheter based systems or radioactive implantable stents are available to deliver the required dose. Catheter based systems seem more flexible in a number of considerations. On the other hand they require a substantial amount of hardware. Beta-emitting stents are implanted via a conventional stent delivery system with small shielding modifications. However, stents emit an inhomogeneous radiation profile due to the mesh-like structure. In addition, not every lesion can be reached by a stent nor does every lesion require a stent solely to deliver radiation. External irradiation is presently not recommended due to its ineffectiveness and the high rate of side effects. In the experimental setting the porcine model comes closest to the clinical situation in man. Animal experiments have demonstrated the effective reduction of intimal proliferation using beta- and gamma-sources in a wide dose range of 3 to 56 Gy. Although the initial and early results are convincing little is know about the long term results. Only few studies have been and are currently performed in patients. Some of these investigations demonstrate a significant reduction of restenosis rate after 6 months. Again, information on long-term results are lacking. It has to be considered that perivascular fibrosis, which may occur with a delay of 5 to 10 years depending on the dosage, could curtail the initial success. Intracoronary irradiation is a promising method for the prevention of restenosis. The dose finding with respect to the dose effect relation, the determination of the therapeutic window and the timing of irradiation have to be further defined in the clinical setting. Nevertheless, intracoronary irradiation remains high on the priority list in fighting restenosis.

Complete AV block following mediastinal radiation therapy: electrocardiographic and pathologic correlation and review of the world literature

The clinical, features, serial electrocardiograms, and autopsy findings of a patient with symptomatic complete AV block, who had received mediastinal radiation therapy 8 1/2 years previously, are presented. The cardiac histopathology disclosed immense fibrosis of the conduction system and of the atria and ventricles. The enormous amount of fibrosis was similar in location and intensity to that observed in our previously reported patient (Cohen et al., Arch Intern Med 1981; 141:676-679) who had undergone mediastinal radiation. We conclude that the severe fibrosis was primarily due to radiation, rather than secondary to atherosclerotic coronary artery disease, which also has been described as a consequence of mediastinal radiotherapy. This patient's serial electrocardiograms disclosed evidence of complete block both in the AV nodal area and infra His system, which correlated well with the histopathology. The characteristic clinical features of patients with symptomatic complete AV block post mediastinal radiation therapy are presented, along with a review of the world literature.

Directional coronary atherectomy for the diagnosis and treatment of radiation-induced coronary artery stenosis

While radiation therapy has been known to cause myocardial and pericardial damage, its role in accentuating coronary artery disease in the absence of traditional cardiovascular risk factors has been controversial. As younger patients with treatable cancers are being treated with mediastinal radiation, coronary artery disease as a cause for severe chest pain should be entertained as a possible diagnosis. We describe a 25-year-old male who presented with an inferior wall myocardial infarction 6 years after receiving mediastinal radiation and chemotherapy for Hodgkin's disease. He was subsequently treated by directional atherectomy to a 95% lesion in the right coronary artery. Histological examination of the atherectomy specimen revealed evidence of radiation-induced endothelial damage that had resulted in plaque formation and subsequent ischemia. Possible mechanisms for radiation-induced coronary artery disease and treatment options are discussed.

Late cardiac effects after treatment for childhood Hodgkin's disease with chemotherapy and low-dose radiotherapy

Twenty-four patients under 18 years when treated for Hodgkin's disease (20 male, four female) were examined no less than five years after the completion of the treatment. The mean age was 17 years (range 9.5-25.0 years) at the time of study. All patients received six courses of cyclophosphamide-oncovin-procarbazine-prednisolone chemotherapy; in addition, nine patients received low-dose radiotherapy excluding the mediastinum and eight of 24 patients received mediastinal radiotherapy; the dose was between 20-30 Gy. All patients had normal cardiovascular findings on clinical examination. ECG and chest radiography were within normal limits in all patients. Resting left ventricular ejection fraction and fractional shortening were decreased in only one patient (4%), but there was no significant difference between the patient group and a control group for left ventricular systolic function (p > 0.05). In the patient group, early diastolic peak velocity, peak velocity at atrial contraction, left ventricular isovolumic relaxation time, and the rate of decrease of flow velocity in early diastole were significantly different from that of the control group (p < 0.05). In conclusion, the late effects of our treatment protocol for Hodgkin's disease appear to be minimal. These observations support combined modality, low-dose irradiation regimens in children and adolescents and suggest the need for careful cardiac screening of treated patients.

Endovascular low-dose irradiation inhibits neointima formation after coronary artery balloon injury in swine. A possible role for radiation therapy in restenosis prevention

BACKGROUND

Restenosis after percutaneous transluminal coronary angioplasty remains a major limitation of the long-term success of this procedure. Restenosis is a form of wound healing. Low-dose ionizing radiation has been effective in inhibiting exuberant wound healing responses in a variety of clinical situations.

METHODS AND RESULTS

Vascular neointimal lesions resembling human restenosis were created in the coronary arteries of normal pigs by overstretch balloon angioplasty injury. To test the effect of low-dose endovascular gamma radiation on lesion formation, a high-activity 192Ir source was introduced into one of the injured arteries in each animal and left in place for a period sufficient to deliver one of three doses: 350, 700, or 1400 cGy. To test potential benefits of delayed irradiation, 700 cGy was given in another group 2 days after injury. Animals were killed 14 days after balloon injury and the coronary vasculature was pressure-perfusion fixed. To test the late effect and safety of endovascular low-dose irradiation, 700 or 1400 cGy was given in miniswine coronary arteries after injury as well as in noninjured carotid arteries; this group was followed up for 6 months. Tissue sections were measured by computer-assisted planimetry. All arteries treated with radiation demonstrated significantly decreased neointima formation compared with control arteries. The ratio of intimal area-to-medial fracture length (IA/FL) was inversely correlated with the different radiation doses: control, 0.59; 350 cGy, 0.38; 700 cGy, 0.42; and 1400 cGy, 0.17 (r = -0.75, P < .0001). Delay of 700-cGy irradiation for 2 days after injury significantly decreased neointima formation compared with the same dose given immediately after injury. Analysis of long-term specimens showed reduction of IA/FL in the arteries irradiated with 700 cGy (0.3, P = .009) and 1400 cGy (0.31, P = .001) compared with control arteries (0.50). There was no excess fibrosis in the media, adventitia, or perivascular space of the coronary arteries or adjacent myocardium in pigs that received radiation compared with control animals.

CONCLUSIONS

Low-dose intracoronary irradiation delivered to the site of coronary arterial overstretch balloon injury in pigs inhibited subsequent intimal thickening (hyperplasia). A dose-response relationship was demonstrated, and delay of treatment for 48 hours appeared to augment the inhibitory effect. Six months of follow-up without fibrosis or arteriosclerosis demonstrated the durability of the beneficial effect in the treated group. These data suggest that intracoronary irradiation therapy may aid in preventing clinical restenosis.

Effects of ionizing irradiation on endothelial cell transglutaminase

The activity of transglutaminase (TG) was measured in cultures of bovine aortic and capillary endothelial cells (EC) following exposure to gamma-irradiation. Resting confluent EC express significant TG activity which fluctuates in growing cells. This activity was increased by 2-fold following non-lethal irradiation. The increase in TG activity was dose dependent up to 20 Gy and reached a plateau at 24-36 h after irradiation. Immunohistochemical studies showed a prominent increase in cytoplasmic TG following irradiation. Western blot analysis of whole cell extracts showed no increase in total cellular TG. Kinetic studies demonstrated that the affinity of the enzyme to its substrate was not altered, but the Vmax was increased. TG has previously been shown to be stored in an inactive form in EC membranes. This activity could be recovered in normal EC, but not in irradiated EC, by the addition of potassium thiocyanate and dithiothreitol or 0.8 M NaCl. An inhibitor of TG was previously demonstrated in the 100,000 x g particulate fraction of EC. Following irradiation, a significant decrease in this inhibitory activity was demonstrated. These results imply that the post-irradiation enhancement of TG activity may be caused by activation of a latent cellular enzyme. This elevated TG activity may cross-link adjacent cytoplasmic and membrane proteins and may thus play an active role in the enhanced apoptosis observed following irradiation of EC.

Radiation-induced stenosis of the left main coronary artery

Isolated left main coronary artery stenosis induced by mediastinal radiation is a well-documented but rare entity. Its clinical manifestations can be latent for many years, but its ominous sequela cannot be ignored. We report here such a patient presenting 16 yr postmediastinal radiation, the longest documented latency to date.

Myocardial infarction in young patients with Hodgkin's disease--potential pathogenic role of radiotherapy, chemotherapy, and splenectomy

Among a total of 2147 patients admitted to our hospital for acute myocardial infarction between 1978 and 1987, three young patients aged 24, 29, and 39 years had previously been treated for Hodgkin's disease. Staging laparotomy, including splenectomy, had been performed in all three patients. Two patients had both mediastinal irradiation (21 and 27 months before infarction) and chemotherapy. In the first patient, postmortem histologic examination of the coronary arteries revealed fibrotic changes, which were probably induced by radiotherapy. In our second patient, myocardial infarction developed 5 days after vinblastine treatment; early angiography showed thrombotic occlusion of the proximal right coronary artery, which was recanalized using the diagnostic Sones catheter. Subsequent angiography revealed normal coronary arteries. This is, to our knowledge, the first case of documented coronary artery thrombosis after treatment with vinca-alkaloids. In our third patient, neither mediastinal irradiation nor chemotherapy had been performed prior to myocardial infarction. However, a marked increase in platelet counts following splenectomy was observed in this patient. The role of radiotherapy, chemotherapy, and splenectomy with consecutive thrombocytosis as a third possible pathogenic factor for subsequent development of myocardial infarction is discussed.

Radiation-induced coronary artery disease

Excessive unprotected radiation to the heart appears to lead to the development of CAD, even in the absence of significant cardiovascular risk factors. The coexistence of such factors may enhance the probability of CAD. The presence of hypercholesterolemia and concomitant or sequential use of chemotherapeutic agents (especially doxorubicin) could further increase this risk. Therapeutic decisions, as with any other manifestation of CAD, relate to the extent of myocardium at jeopardy and to the overall diffuseness of CAD. Management options possible are PTCA or coronary artery bypass surgery. The latter may be required in left main artery stenosis and complicated ostial lesions. Use of shielding should decrease the associated risk of radiation-induced CAD in future years. However, clinicians should continue to have a high degree of suspicion of CAD in patients treated with thoracic radiation without cardiac shielding.

Increase in plasma thrombomodulin and decrease in plasma von Willebrand factor after regular radiotherapy of patients with cancer

In this study, we investigated plasma levels of thrombomodulin (TM) and von Willebrand factor (vWF) in 51 patients suffering from cancer or tumor undergoing 60 cobalt radiotherapy. Plasma TM and vWF antigen were measured by immunoradiometric assay and ELISA, respectively. During radiotherapy, an increase in plasma TM in patients was observed, which was radiation-dose dependent and there was a positive correlation between plasma TM level and radiation doses. However, the level of plasma vWF in the patients was decreased during radiotherapy and there was an inverse correlation between the amount of plasma vWF and radiation doses. Our data indicate that plasma TM is an useful molecular marker for early detection of radiation injury to endothelial cells in patients undergoing radiotherapy.

Late cardiopulmonary toxicity after treatment for Hodgkin's disease

Cardiac and pulmonary functions were evaluated in 75 patients aged 50 years or under, treated for Hodgkin's disease by mantle radiotherapy at least 3 years earlier; all received the same mantle field radiotherapy: radiotherapy alone, MOPP chemotherapy plus radiotherapy, MOPP and ABVD chemotherapy plus radiotherapy. No patient had any symptom of heart disease. Only borderline abnormalities of ECG or echocardiogram were observed in 12 patients. One of them showed a moderate aortic stenosis which was known before the treatment; apical or septum hypokinesia were present in four patients and one patient had a slightly right ventricular dilatation. Twelve (16%) chest radiographs showed moderate or severe abnormalities, but there was no significant correlation between the results of pulmonary function tests and Xenon ventilation/perfusion scintigraphy, the clinical examination and the intensity of the radiological sequelae. Twenty-nine (64%) Xenon scintigraphies showed a reduction of lung perfusion in the irradiated areas without any symptom. The resting mean pulmonary function test was significantly lower for the patients than for the control group with regard to Total Capacity and Vital Capacity. The exercise tolerance, as indicated by analysis of blood gases, was below the one expected for only two patients who were dyspneic during the low level of exercise. We did not find any significant difference between the three treatment groups. We conclude that the treatment with mantle field under good technical conditions (high energy photons, moderate doses...) can result in minimal cardiopulmonary dysfunction.

An updated dose-response analysis in Hodgkin's disease

Although radiotherapy cures a very high percentage of early stage patients with Hodgkin's disease (HD), there is a controversial dichotomy in the dose recommendations believed necessary to achieve greater than 95% local control: Whereas one school of thought is to administer 40-44 Gy, other reports claim equal results with about 36 Gy. It is also not clear what doses are required for various tumor cell burdens. The original recommendation of 40-44 Gy was derived from a retrospective analysis of in-field control of disease from mostly kilovoltage data three decades ago. However, there have been many advances in the evaluation of the extent of the disease and in the practice of radiotherapy since the 1960s. Many more dose-control studies have been published in recent years, necessitating a revisit to the dose-response question in HD. Here we have compiled the dose-control data from the 60s to the 90s and analyzed the original and the updated data with the same statistical method to see any differences. We also have performed similar analysis of dose-control information for subclinical disease, less than 6 cm and greater than 6 cm disease. Whereas original analysis (1040 sites at risk) suggested 98% in-field control with 44 Gy, our re-analysis including modern megavoltage data (4117 sites at risk) shows that similar in-field control rates could be achieved with 37.5 Gy. With megavoltage radiotherapy, the doses required for 98% in-field control for subclinical disease and disease of less than 6 cm and greater than 6 cm are, 32.4 Gy (1426 sites at risk), 36.9 Gy (1005 sites at risk) and 37.4 Gy (98 sites at risk), respectively. The results of current updated analysis will provide in-field disease control probabilities for different disease burdens and can serve as a guide in deciding dose prescriptions for practicing radiation oncologists.

Coronary artery operation in radiation-associated atherosclerosis: long-term follow-up

Radiation-associated coronary atherosclerosis is a potential problem for patients who have had mediastinal irradiation for malignant tumors. This study identified 14 patients with radiation-associated coronary atherosclerosis, defines unique population characteristics, and analyses postsurgical problems and long-term outcome. Fourteen patients with radiation-associated coronary atherosclerosis and class III and IV New York Heart Association symptoms were identified because of mediastinal or chest wall irradiation (30 Gy) associated with anterior epicardial discoloration or fibrosis, aortitis with adventitial thickening, and inflammatory process over a proximal coronary artery. Two distinct treatment groups were analyzed. Coronary artery operation resulted in one hospital death, with vein grafts being used predominantly. The internal mammary artery could only be used in 3 patients because of vessel friability and mediastinal fibrosis. Postoperative right ventricular dysfunction and pulmonary problems were frequent. Severe pericardial inflammatory complications (fibrosis with graft closure, and constrictive pericarditis) present in 2 early patients resulted in routine anterior pericardiectomy after coronary artery operation without further problems. Long-term follow-up (100%) (range, 11 to 74 months) revealed that 1 patient died late and of the remainder (12 patients), 11 were in New York Heart Association class I and 1 in class II, experiencing three myocardial events. Thus, patients with radiation-associated coronary atherosclerosis have a low operative mortality but have risk of early right ventricular and pulmonary dysfunction. The routine use of internal mammary artery may not be possible and anterior pericardiectomy is recommended. Long-term results are excellent and no evidence of accelerated disease has been noted.

Effect of external beam irradiation on neointimal hyperplasia after experimental coronary artery injury

Human coronary artery restenosis after percutaneous revascularization is a response to mechanical injury. Smooth muscle cell proliferation is a major component of restenosis, resulting in obstructive neointimal hyperplasia. Because ionizing radiation inhibits cellular proliferation, this study tested in a porcine coronary injury model the hypothesis that the hyperplastic response to coronary artery injury would be attenuated by X-irradiation. Deep arterial injury was produced in 37 porcine left anterior descending coronary artery segments with overexpanded, percutaneously delivered tantalum wire coils. Three groups of pigs were irradiated with 300-kV X-rays after coil injury: Group I (n = 10), 400 cGy at 1 day; Group II (n = 10), 400 cGy at 1 day and 400 cGy at 4 days and Group III (n = 9), 800 cGy at 1 day. Eight pigs in the control group underwent identical injury but received no radiation. Treatment efficacy was histologically assessed by measuring neointimal thickness and percent area stenosis. Mean neointimal thickness in all irradiated groups was significantly higher than in the control groups and thickness was proportional to X-ray dose. X-irradiation delivered at these doses and times did not inhibit proliferative neointima. Rather, it accentuated the neointimal response to acute arterial injury and may have potentiated that injury.

Irradiation-induced atherosclerosis: a factor in therapeutic planning

Early primary head and neck cancers (stages I and II) and occult metastatic neck disease have caused debate regarding the choice between surgery and irradiation. The arguments for each are reviewed with a new consideration: the acceleration and/or induction of carotid atherosclerosis in irradiated patients. We present clinical case reports (n = 9), a retrospective clinical evaluation for the occurrence of carotid atherosclerosis in irradiated head and neck cancer patients (n = 57) and a comparison study of the extent and distribution of atherosclerosis in irradiated (n = 29) and nonirradiated head and neck cancer patients controlled for age, blood pressure, and tobacco use. The results show that carotid atherosclerosis is found in a wider anatomic distribution and to a greater extent in irradiated than in nonirradiated patients. We conclude that carotid atherosclerosis is induced and/or accelerated by neck irradiation. The implications as they relate to choice of treatment, to pretreatment evaluations, and to long-term follow-up are discussed.

Chemotherapy-induced myocardial infarction in a young man with hodgkin's disease

A 32-year-old male with stage IIIA nodular sclerosing Hodgkin's disease and no cardiac risk factors presented with chest pain after receiving chemotherapy consisting of multiple drugs, including vinca alkaloids. He completed an uncomplicated anterior wall myocardial infarction. Coronary angiography documented the absence of significant coronary artery disease. Exercise stress testing with gated scan confirmed loss of anterior wall motion and a decreased left ventricular ejection fraction. Vascular toxicity, including, rarely, myocardial infarction, has been reported following antineoplastic regimens containing vinca alkaloids. Hypercoagulable states, cardiac invasion by tumor, and coronary artery spasm are possible etiologies. Of these, coronary artery spasm appears most likely. Management should include discontinuation of the offending drug and supportive care.

Heart disease after mediastinal radiotherapy

The greatest risk for most cancer patients is inadequate treatment of their disease. Although mediastinal radiotherapy is a safer procedure than it was 20 years ago, it still may damage the thoracic viscera, including the heart. Cardiovascular problems tend to present subtly years later, when the patient may not recall the prior radiation or may not deem it significant. An awareness of this long latency period and of the wide spectrum of heart disease that may result from radiotherapy is essential for management of these patients.

Long-term sequelae of autologous bone marrow or peripheral stem cell transplantation for lymphoid malignancies

The study was made to evaluate the long-term physical and psychosocial changes after high-dose therapy and autologous bone marrow or peripheral stem transplantation for recurrent lymphoid malignancies. Patients who had undergone high dose therapy and autologous bone marrow or peripheral stem cell transplantation for recurrent lymphoid malignancies at least 1 year previously were contacted by phone interview regarding their status after the transplant. The patients' comments were confirmed by checking medical records when possible. Fifty patients who had undergone transplantation at the University of Nebraska Medical Center at least 1 year before the interview were available for interview and willing to answer questions. After transplant, many patients noticed temporary changes in their appearance, which usually returned to normal within 1 year. Few patients reported remarkable cardiovascular, gastrointestinal, or pulmonary changes after transplantation. However, up to one-third of the patients reported changes in sexual function or desire. The most common infectious problem after transplant was Herpes zoster, which occurred in 25% of the patients. Overall, the patients had a positive outlook after high-dose therapy and transplantation, with most being able to return to work and enjoy a normal life style. Ninety-six percent of the patients stated that they would be willing to undergo high-dose therapy and transplantation again under the same circumstances.