Dutch Study Finds No Increased Risk of Cardiovascular Mortality in 5-Year Survivors of DCIS
In a Dutch study reported in the Journal of the National Cancer Institute, Boekel et al found no increase in risk of cardiovascular mortality among 5-year survivors of ductal carcinoma in situ (DCIS) compared with the general population. Among DCIS patients, risk of cardiovascular events did not differ according to surgery vs radiotherapy or according to left- vs right-sided radiotherapy.
Study Details
The study included data on all DCIS patients in the Netherlands between 1989 and 2004 diagnosed at age < 75 years (N = 10,444). Cardiovascular disease data were obtained through linkage with population-based registries. Standardized mortality ratios (SMRs) were calculated by comparing mortality vs that in the Dutch female population, adjusting for person-years of observation.
In total, 54% of patients had left-sided DCIS, 28% received radiotherapy, and 2% had a history of cardiovascular disease prior to DCIS diagnosis. Median follow-up was 10 years among all patients and 8 years among those receiving radiotherapy.
In total, 950 patients (9%) experienced a cardiovascular event, with 814 admitted to the hospital, 255 undergoing a cardiovascular intervention, and 282 dying from cardiovascular disease.
Mortality Rates
Among 5-year survivors of DCIS, risk of all-cause mortality (SMR = 1.04, 95% confidence interval [CI] = 0.97–1.11) was similar and risk of death due to cardiovascular disease (SMR = 0.77, 95% CI = 0.67–0.89) was significantly reduced compared with the general population. SMRs did not differ by age at diagnosis, treatment period, follow-up interval, or treatment, or for all cardiovascular deaths combined or death due to myocardial infarction, other ischemic heart disease, or other heart disease analyzed separately.
Risk of Events
Among 5-year survivors, there were no significant increases in risk for a cardiovascular event among patients receiving right-sided radiotherapy (hazard ratio [HR] = 1.08, 95% CI = 0.83–1.41) or left-sided radiotherapy (HR = 1.01, 95% CI = 0.79–1.30) vs surgery alone or between left- vs right-sided radiotherapy (HR = 0.94, 95% CI = 0.67–1.32). There were no significant increases in risk for cardiovascular death among patients receiving right-sided radiotherapy (HR = 1.29, 95% CI = 0.72–2.31) or left-sided radiotherapy (HR = 0.89, 95% CI = 0.48–1.66) vs surgery alone or between left- vs right-sided radiotherapy (HR = 0.70, 95% CI = 0.31–1.56).
In an analysis of DCIS patients diagnosed between 1997 and 2005 that assessed risk from directly after DCIS diagnosis and adjusted for history of cardiovascular disease, there was no significant difference in risk for cardiovascular events between patients receiving left- vs right-sided radiotherapy (HR = 0.94, 95% CI = 0.68–1.29).
The investigators concluded: “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.”
Flora E. van Leeuwen, PhD, of the Netherlands Cancer Institute, is the corresponding author for the Journal of the National Cancer Institute article.
The study was supported by the Dutch Cancer Society. The study authors reported no potential conflicts of interest.
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