Modern Radiation Therapy and Cardiac Outcomes in Breast Cancer

Int J Radiat Oncol Biol Phys. 2016 Mar 15;94(4):700-8. doi: 10.1016/j.ijrobp.2015.12.018. Epub 2015 Dec 17.


Purpose: Adjuvant radiation therapy, which has proven benefit against breast cancer, has historically been associated with an increased incidence of ischemic heart disease. Modern techniques have reduced this risk, but a detailed evaluation has not recently been conducted. The present study evaluated the effect of current radiation practices on ischemia-related cardiac events and procedures in a population-based study of older women with nonmetastatic breast cancer.

Methods and materials: A total of 29,102 patients diagnosed from 2000 to 2009 were identified from the Surveillance, Epidemiology, and End Results-Medicare database. Medicare claims were used to identify the radiation therapy and cardiac outcomes. Competing risk models were used to assess the effect of radiation on these outcomes.

Results: Patients with left-sided breast cancer had a small increase in their risk of percutaneous coronary intervention (PCI) after radiation therapy-the 10-year cumulative incidence for these patients was 5.5% (95% confidence interval [CI] 4.9%-6.2%) and 4.5% (95% CI 4.0%-5.0%) for right-sided patients. This risk was limited to women with previous cardiac disease. For patients who underwent PCI, those with left-sided breast cancer had a significantly increased risk of cardiac mortality with a subdistribution hazard ratio of 2.02 (95% CI 1.23-3.34). No other outcome, including cardiac mortality for the entire cohort, showed a significant relationship with tumor laterality.

Conclusions: For women with a history of cardiac disease, those with left-sided breast cancer who underwent radiation therapy had increased rates of PCI and a survival decrement if treated with PCI. The results of the present study could help cardiologists and radiation oncologists better stratify patients who need more aggressive cardioprotective techniques.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arrhythmias, Cardiac / diagnosis
  • Arrhythmias, Cardiac / epidemiology
  • Confidence Intervals
  • Female
  • Heart / radiation effects
  • Heart Diseases / mortality
  • Heart Diseases / therapy*
  • Humans
  • Medicare / statistics & numerical data
  • Myocardial Ischemia / complications
  • Myocardial Ischemia / etiology
  • Myocardial Ischemia / mortality
  • Percutaneous Coronary Intervention / statistics & numerical data*
  • SEER Program
  • Unilateral Breast Neoplasms / complications
  • Unilateral Breast Neoplasms / mortality
  • Unilateral Breast Neoplasms / radiotherapy*
  • United States