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

Plaque Rupture in a Hodgkin Lymphoma Survivor without Cardiovascular Risk Factors 20 Years after Thoracic Radiotherapy: A Case Report

BACKGROUND

Major improvements in cancer therapies have significantly contributed to increased survival rates of Hodgkin lymphoma (HL) survivors, outweighing cardiovascular side effects and the risks of radiation-induced heart disease. Non-invasive screening for coronary artery disease (CAD) starting five years after irradiation is recommended, as plaque development and morphology may differ in this high-risk population. Due to rapid plaque progression and a possibly higher incidence of non-calcified plaques, coronary artery calcium scoring may not be sufficient as a screening modality in HL survivors treated with thoracic radiotherapy.

CASE SUMMARY

A 42-year-old man with a history of HL treated with thoracic radiotherapy presented at the emergency department 20 years after cancer treatment with an ST-elevation myocardial infarction, in the absence of cardiovascular risk factors, for which primary percutaneous coronary intervention of the left anterior descending artery was performed. Four months prior to acute myocardial infarction, invasive coronary angiography only showed wall irregularities. Two years earlier, the Agatston calcium score was zero.

DISCUSSION

In HL survivors treated with thoracic radiotherapy, a calcium score of zero may not give the same warranty period for cardiac event-free survival compared to the general population. Coronary computed tomography angiography can be a proper diagnostic tool to detect CAD at an early stage after mediastinal irradiation, as performing calcium scoring may not be sufficient in this population to detect non-calcified plaques, which may show rapid progression and lead to acute coronary syndrome. Also, intensive lipid-lowering therapy should be considered in the presence of atherosclerosis in this patient population.

Dose rate effect on mortality from ischemic heart disease in the cohort of Russian Mayak Production Association workers

For improvement of the radiation protection system it is crucial to know the factors that modify the radiation dose-response relationship. One of such key factors is the ionizing radiation dose rate. There are, however, very few studies that examine the impact of the dose rate on radiogenic risks observed in human cohorts exposed to radiation at various dose rates. Here we investigated the impact of the dose rate (in terms of the recorded annual dose) on ischemic heart disease (IHD) mortality among Russian nuclear workers chronically exposed to radiation. We observed significantly increased excess relative risks (ERR) of IHD mortality per unit of external gamma-ray absorbed dose accumulated at higher dose rates (0.005-0.050 Gy/year). The present findings provide evidence for the association between radiation dose rate and ERRs of IHD mortality in occupationally chronically exposed workers per unit total dose. IHD mortality risk estimates considerably increased with increasing duration of uninterrupted radiation exposure at high rates. The present findings are consistent with other studies and can contribute to the scientific basis for recommendations on the radiation protection system.

Effect of Radiation Dose Rate on Circulatory Disease Mortality among Nuclear Workers: Reanalysis of Hanford Data

The excess relative risk (ERR) of mortality for circulatory disease among nuclear workers was reanalyzed by taking into consideration the annual dose as the dose rate using publicly available epidemiological data of the Hanford site dedicated to the cohort study of nuclear workers in the US, the UK, and Canada. Values of the dose rate (cut-points) were chosen at 2 mSv y intervals from 2 to 40 mSv y, and risk estimates were made for 32,988 workers, considering the doses accumulated below and above each cut-point to have different effects. Similarly to that in the previous study for cancer by Sasaki et al., examinations of sensitivity analysis were also carried out for different risk models, lag periods, and impacts of adjusting the monitoring period to find the effect of the dose rate. As a result, emergence of a statistically significant difference between βL1, which is the ERR for the doses accumulated below the specified cut-point, and βH1, which is the ERR for that above the specified cut-point, was observed for cut-point of the dose rate of 4, 6, 34, 36, and 38 mSv y. While statistically negative values were estimated for βL1 (4 and 6 mSv y) and for βH1 (34, 36, and 38 mSv y), the overall relationship between the ERR and the cut-point of the dose rate was found to be similar to that obtained by the analysis of the mortality for all cancers excluding leukemia.

Radiotherapy Is Associated with an Accelerated Risk of Ischemic Stroke in Oral Cavity Cancer Survivors after Primary Surgery

The number of oral cavity carcinoma (OCC) survivors continues to increase due to advances in definitive surgery and radiation therapy (RT), however the risk of ischemic stroke is unclear in long-term survivors. In this study, survivors are defined as those who survived for >5 years after a diagnosis of OCC. They were matched at a 1:5 ratio with normal controls. Those who received surgery alone versus surgery+RT were also matched at a 1:1 ratio. From 2000 to 2005, 5172 OCC survivors who received surgery alone (n = 3205) or surgery+RT (n = 1967), and 25,860 matched normal controls were analyzed using stratified Cox regression models. Adjusted HRs (aHR) revealed that the surgery+RT group (aHR = 1.68, p < 0.001) had an elevated risk of stroke, but this was not seen in the surgery alone group (aHR = 0.99, p = 0.953). Furthermore, the age at stroke onset was at least 10 years earlier in the surgery+RT group than in the controls. In conclusion, radiotherapy increased the risk of ischemic stroke by 68% and also accelerated the onset of stroke in long-term OCC survivors after primary surgery compared with matched normal controls. Secondary prevention should include stroke as a late complication in OCC survivorship programs.

Prevalence of carotid stenosis following radiotherapy for head and neck cancer: A systematic review and meta-analysis

BACKGROUND

Radiation to the head and neck is a well-established risk factor for the development of carotid artery stenosis. Our objective was to identify the prevalence, incidence, and degree of carotid stenosis in patients with a history of head and neck irradiation.

METHODS

This study was performed according to the PRISMA guidelines. A random effects model meta-analysis was conducted.

RESULTS

Nineteen studies comprising 1479 patients were included. The prevalence of carotid stenosis >50%, >70%, and carotid occlusion was 25% (95% CI: 19%-32%), 12% (95% CI: 7%-17%), and 4% (95% CI: 2%-8%), respectively. The cumulative 12-month incidence of carotid stenosis >50% was 4% (95% CI: 2%-5%), the 24-month was 12% (95% CI: 9%-15%), and the 36-month was 21% (95% CI: 9%-36%).

CONCLUSIONS

The yearly incidence of carotid stenosis >50% increased every year during the first 3 years following radiotherapy. We propose routine yearly Doppler ultrasound screening beginning 1 year after head and neck radiotherapy.

Accelerated Risk of Premature Ischemic Stroke in 5-Year Survivors of Nasopharyngeal Carcinoma

BACKGROUND

Research on cancer survivorship associated with nasopharyngeal carcinoma (NPC) is rare. We aimed to elucidate the risk of ischemic stroke in 5-year survivors of NPC following radiotherapy (RT) or concurrent chemoradiation therapy (CCRT).

SUBJECTS, MATERIALS, AND METHODS

NPC survivors, defined as those who survived longer than 5 years after diagnosis, were identified and matched at a 1:5 ratio with normal controls from the Longitudinal Health Insurance Database 2005 of Taiwan. The stratified Cox regression models were used to access the risk of ischemic stroke, with adjustment for age, treatment modality, comorbidities, and socioeconomic characteristics.

RESULTS

From 2000 to 2005, a total of 3,016 NPC survivors who had received RT (n = 959) or CCRT (n = 2,057) and 15,080 controls were matched for age, sex, income, and urbanization level. The risk of ischemic stroke was significantly higher in the NPC survivor cohort than in the control cohort. Stroke was positively related to death. Moreover, the age onset of stroke for NPC survivors was 10 years earlier than that for the general population.

CONCLUSION

Not only was the stroke risk in NPC survivors higher than that in the general population, but the onset age was also 10 years earlier. Future survivorship care should include ischemic stroke as a late complication, for its proper prevention and management.

IMPLICATIONS FOR PRACTICE

Nasopharyngeal carcinoma (NPC) is endemic in Taiwan, and its 5-year survival is 65.2%. With the increased 5-year cancer survivors, survivorship has become an important issue. However, research on NPC survivorship is very rare. To the authors' knowledge, this is the first population-based study on long-term NPC survivors. This study's results indicated that not only was the risk of ischemic stroke in NPC survivors at least triple that of the general population, but the onset age was also 10 years earlier. These results may provide solid evidence that survivorship care guidelines should include stroke as a late complication in 5-year NPC survivors, for its proper prevention and management.