A systematic review 1 including 14 retrospective studies with a total of 14,417 subjects was abstracted in DARE. Four studies showed significantly increased standardized mortality ratios (SMRs) after radiotherapy in comparison with the general population. The pooled SMR of 28.4 was based on 4 studies. The absolute excess risk ranged from -0.4 to +17.7 excess cardiac deaths per 10,000 person-years adjusted for age, gender, race and calendar period (4 studies). The actuarial risk for CVM increased from 0.3% at 10 years to 10.2% after 25 years (2 studies). The RR of cardiovascular disease (both cardiovascular events and CVM) following radiation was reported in 3 studies. Two of the 3 studies showed a significantly increased risk with radiation compared with no radiation.
Comment: The quality of evidence is downgraded by retrospective study settings and upgraded by consistency of results.
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