Wadsten C, et al. - Researchers assessed the frequency of ischemic heart disease (IHD) in a population-based cohort of women with ductal carcinoma in situ (DCIS). Data on comorbidity, socioeconomic status and incidence of IHD was attained via linkage with population-based registers. Analysis of hazard ratios (HR) for IHD with 95% confidence intervals (CI) was carried out. After a median follow-up of 8.8 years, relative to non-irradiated women and to the comparison cohort, women with DCIS allocated to radiotherapy (RT) had lower risk of IHD, most likely owing to patient selection. Any over-risk for irradiation of the left breast was not demonstrated in comparison of RT by laterality.