HF, arrythmias more common after radiation-treated breast cancer vs. matched controls
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Key takeaways:
- In the decade after radiation for breast cancer, cardiovascular death was second to cancer mortality.
- Heart failure and arrhythmias were more common among those with breast cancer vs. risk-matched controls.
In the 10 years after radiotherapy for breast cancer, the rate of CV mortality remained second to cancer mortality; however, patients had increased incidence of HF and arrhythmias compared with matched controls, researchers reported.
“Little is known about cardiac side effects in the first 10 years after radiotherapy,” Johanna E. J. Jacobs, MD, resident and PhD candidate in the department of cardiovascular diseases at University Hospitals Leuven, Belgium, and colleagues wrote. “Our objective was to compare the rates of mortality and major adverse cardiac events in the first decade following contemporary radiation therapy as part of the curative treatment regimen for unilateral breast cancer with those observed in age- and risk factor-matched controls.”
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For this analysis, researchers matched 1,095 women with unilateral breast cancer (mean age, 56 years) to 904 risk-matched women who participated in the Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO).
Risk for mortality and CV events
In the first 10 years after radiotherapy for breast cancer, 19.9% of women died, of which 49.1% of deaths were cancer-related and 10.1% were CV-related.
CV mortality was lower among patients with breast cancer compared with matched controls (RR = 0.3; 95% CI, 0.17-0.55; P < .0001), yet both non-CV mortality (RR = 2.46; 95% CI, 1.88-3.2; P < .0001) and cancer mortality (RR = 1.79; 95% CI, 1.29-2.48; P = .0005) were more common among those with breast cancer.
CAD incidence was similar between the two groups (RR = 0.75; 95% CI, 0.48-1.18; P = .2115); however, the incidence of HF (RR = 1.97; 95% CI, 1.19-3.25; P = .0081), nonfatal HF (RR = 2.3; 95% CI, 1.35-3.94; P = .0023) and atrial fibrillation/flutter (RR = 1.82; 95% CI, 1.07-3.08; P = .0259) were more common among women with breast cancer compared with matched controls with a similar risk profile.
Factors tied to mortality and CV event risk
During the 10 years after radiotherapy, the researchers reported that elevated age (HR = 1.033; 95% CI, 1.006-1.061; P = .016), tumor grade (HR = 1.739; 95% CI, 1.166-2.591; P = .007) and neoadjuvant treatment setting (HR = 2.782; 95% CI, 1.304-5.936; P = .008) were each risk factors for mortality within the breast cancer cohort.
Moreover, risk factors for major adverse cardiac events among patients with breast cancer included:
- age (HR = 1.053; 95% CI, 1.013-1.093; P = .008);
- mean heart dose of radiation (HR = 1.093; 95% CI, 1.025-1.167; P = .007);
- prior CVD (HR = 2.386; 95% CI, 1.096-6.197; P = .029); and
- Mayo Clinic Cardiotoxicity Risk score (HR = 2.664; 95% CI, 1.625-4.367; P < .001).
“Mortality within 10 years following curative treatment including radiation therapy for unilateral breast cancer was mainly attributable to cancer death,” the researchers wrote. “Despite the competing risk of cancer death, HF and AF were already common within the first decade of follow-up. This should encourage early dedicated cardiological surveillance and timely introduction of targeted anticoagulant, anti-arrhythmic and evidence-based HF therapies.”
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