February 08, 2017
2 min read

Higher cardiac radiation exposure may increase HF risk in women with breast cancer

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Cardiac radiation exposure from contemporary conformal breast cancer radiotherapy was found to increase the risk for HF with preserved ejection fraction, according to data recently published in Circulation.

“The odds of incident HF after radiotherapy increased with higher mean cardiac radiation dose,” Hirofumi Saiki, MD, PhD, from the department of cardiovascular disease at the Mayo Clinic in Rochester, Minnesota, and colleagues wrote.

In a population-based case-control study, researchers evaluated incident HF in women who underwent contemporary radiotherapy for breast cancer from 1998 to 2013. There were 170 women from Olmsted County, Minnesota, included in the study, all of whom underwent contemporary CT-assisted radiotherapy. The researchers matched 59 women who developed HF with 111 controls who did not by age, tumor side, use of chemotherapy and presence of diabetes and/or hypertension.

The mean age of the patients at radiotherapy was 69 years, and the mean cardiac radiation dose was determined from each patient’s CT images and radiotherapy plan.

The incidence of HF compared with controls increased with higher mean cardiac radiation dose, the researchers wrote. The odds of any incident HF as well as of incident HFpEF was greater with higher mean cardiac radiation dose (OR for HF per log mean cardiac radiation dose = 9.1; 95% CI, 3.4-24.4; OR for HFpEF per log mean cardiac radiation dose = 16.9; 95% CI, 3.9-73.7). This increase remained statistically significant even after adjusting for HF risk factors.

HF with reduced EF increased with higher mean cardiac radiation dose, but the increase was not statistically significant (OR for HFrEF per log mean cardiac radiation dose = 3.17; 95% CI, 0.8-13), Saiki and colleagues wrote.

Among all patients with HF, 64% had HFpEF (EF ≥ 50%); 31% had HFrEF (EF ≤ 50%); and 5% of patients did not have an EF measurement, the researchers wrote.

Among the 56 women with HF that had an EF measurement, the EF was ≥ 40% in 89% (n = 50) of the patients. From the time of radiotherapy to incident HF, the mean interval was 5.8 years. Patients with a prior history of ischemic heart disease or atrial fibrillation had greater odds of incident HF, according to the findings.

New or recurrent ischemic events occurred in 18.6% of patients between radiotherapy and HF onset, Saiki and colleagues wrote.

“In older women, undergoing contemporary breast cancer radiotherapy, the [RR] of HFpEF increases in proportion to calculated [mean cardiac radiation dose], begins within a few years after radiotherapy and is not mediated solely by coronary events. These data suggest that cardiac dose and HF risk factors should be considered in decisions regarding breast cancer radiotherapy and underscore the importance of techniques to reduce cardiac dose. Moreover, these data provide further support for the importance of coronary microvascular compromise in the pathophysiology of HFpEF,” Saiki and colleagues wrote. by Suzanne Reist

Disclosure: The researchers report no relevant financial disclosures.