Radiation exposure and circulatory disease risk: Hiroshima and Nagasaki atomic bomb survivor data, 1950-2003

Abstract

Objective To investigate the degree to which ionising radiation confers risk of mortality from heart disease and stroke. Design Prospective cohort study with more than 50 years of follow-up. Setting Atomic bomb survivors in Hiroshima and Nagasaki, Japan. Participants 86 611 Life Span Study cohort members with individually estimated radiation doses from 0 to >3 Gy (86% received <0.2 Gy). Main outcome measures Mortality from stroke or heart disease as the underlying cause of death and doseresponse relations with atomic bomb radiation. Results About 9600 participants died of stroke and 8400 died of heart disease between 1950 and 2003. For stroke, the estimated excess relative risk per gray was 9% (95% confidence interval 1% to 17%, P=0.02) on the basis of a linear dose-response model, but an indication of possible upward curvature suggested relatively little risk at low doses. For heart disease, the estimated excess relative risk per gray was 14% (6% to 23%, P<0.001); a linear model provided the best fit, suggesting excess risk even at lower doses. However, the dose-response effect over the restricted dose range of 0 to 0.5 Gy was not significant. Prospective data on smoking, alcohol intake, education, occupation, obesity, and diabetes had almost no impact on the radiation risk estimates for either stroke or heart disease, and misdiagnosis of cancers as circulatory diseases could not account for the associations seen. Conclusion Doses above 0.5 Gy are associated with an elevated risk of both stroke and heart disease, but the degree of risk at lower doses is unclear. Stroke and heart disease together account for about one third as many radiation associated excess deaths as do cancers among atomic bomb survivors.

Circulatory disease mortality in the Massachusetts tuberculosis fluoroscopy cohort study

“…Many studies lack this information on lifestyle factors. Of the studies considered in Table 7 only those of the Japanese atomic-bomb survivors [7,48], Mayak workers [49,50], and Canadian fluoroscopy patients [15] had such information. Some lifestyle factors were included in the Nordic breast cancer case-control study [4], and specific medical factors (surgery, thoracoplasty, pneumolobectomy), alcohol consumption, and cigarette smoking were included in the cohort considered here.…”

“…However, the importance of these findings is unclear, and they may best be interpreted as the effects of chance. In all other radiation-exposed groups with such information there is no evidence that lifestyle factors interacted with radiation risk [4,7,[48][49][50].…”

“…Therapeutic doses of ionizing radiation to the heart and large arteries are associated with various types of circulatory disease [3][4][5][6]. More recently, and controversially, studies on several groups exposed to low-to-moderate doses of radiation have reported excess mortality and morbidity from circulatory diseases, in particular the Life Span Study (LSS) of Japanese atomic bomb survivors [7] and several occupationally exposed cohorts [8]. There is biological data suggesting there might be a variant response for circulatory disease below vs above about 0.5 Gy [9].…”

Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer

“…4 Nevertheless, in most women, the heart still receives doses of 1 to 5 Gy. [5][6][7][8][9][10][11] Several studies have suggested that exposures at this level can cause is che mic heart disease, [12][13][14] but the magnitude of the risk after any given dose to the heart is uncertain, as are the time to the development of any radiation-related disease and the influence of other cardiac risk factors. We therefore conducted a study relating the risk of is chemic heart disease after radiotherapy to each woman's radiation dose to the heart and to any cardiac risk factors she had at the time of radiotherapy.…”

From heart to heart for breast cancer patients—cardiovascular toxicities in breast cancer radiotherapy

“…High total doses to the coronary arteries may cause myocardial infarctions 5-20 years after irradiation. There is no evidence that low doses to large volumes of the myocardium may cause myocardial infarction (Abomb survivor studies) [9].…”