Cardiovascular Morbidity and Mortality After Treatment for Ductal Carcinoma In Situ of the Breast

BACKGROUND Recent concerns about potential overdiagnosis and overtreatment of ductal carcinoma in situ of the breast (DCIS) render evaluation of late effects of treatment, such as cardiovascular disease (CVD), of great importance. We studied cardiovascular morbidity and mortality in a large population-based cohort of DCIS patients. METHODS Data on all incident DCIS case patients in the Netherlands between 1989 and 2004 who were diagnosed before the age of 75 years were obtained (n = 10468). CVD data was acquired through linkage with population-based registries. Standardized mortality ratios were calculated by comparing mortality in our cohort with that in the Dutch female population, taking into account person-years of observation. Within-cohort comparisons were based on multivariable competing-risk regression. RESULTS Compared with the general population, 5-year survivors of DCIS had a similar risk of dying due to any cause (standardized mortality ratio [SMR] = 1.04; 95% confidence interval [CI] = 0.97 to 1.11) but a lower risk of dying of CVD (SMR = 0.77; 95% CI = 0.67 to 0.89). No difference in CVD risk was found when comparing 5-year survivors treated with radiotherapy with those treated with surgery only. Left-sided vs right-sided radiotherapy also did not increase this risk (hazard ratio [HR] = 0.94; 95% CI = 0.67 to 1.32). In a subgroup analysis of all DCIS patients diagnosed between 1997 and 2005, we were able to account for history of CVD and did not observe a risk difference between treatment groups (left-sided vs right-sided radiotherapy: HR = 0.94; 95% CI = 0.68 to 1.29). CONCLUSIONS After a median follow-up of 10 years, we did not find an increased risk for cardiovascular morbidity or mortality after radiotherapy for DCIS when comparing surgery and radiotherapy vs surgery only, nor when comparing radiotherapy for left-sided vs right-sided DCIS. Compared with the general population, DCIS patients have a decreased risk of cardiovascular death, independent of treatment.