FIGURE 7-6 Distribution of study-specific estimates of ERR/Gy for stomach cancer according to level of average dose to the stomach.

vascular system following irradiation. These changes are associated with atherosclerosis and the normal aging process, although irradiation may accelerate the development of these conditions (Trivedi and Hannan 2004).

Although the dose required to produce specific conditions or vascular effects is uncertain, it appears that over extended periods, the nature of the changes induced are similar for low doses (on the order of 5 Gy) and for high doses (in the region of 40 Gy). There is a broad spectrum and severity of cardiovascular diseases, with radiation being only one of many possible risk factors that may act directly or indirectly on the vasculature. To clarify the role of radiation in the etiology of cardiovascular diseases, further studies involving long-term, low-level exposures are needed, taking into account all of the known risk factors for cardiovascular outcomes.

Excess heart disease mortality has been observed among women with breast cancer who were irradiated with cobalt-



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