Cardiac Morbidity and Mortality After Breast Conservation Treatment in Early-stage Breast Cancer Patients With Pre-existing Cardiac Disease

Reviewer: Charles Wood, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: November 13, 2006

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Presenter: R. Gutt
Presenter's Affiliation: University of Maryland
Type of Session: Scientific

Background

  • Patients with left-sided breast cancer have been shown to have an increase in the subsequent development of coronary artery disease (CAD) and myocardial infarction (MI), but no increase in mortality versus patients with right-sided breast cancers up to 20 years following contemporary radiotherapy
  • Few data exist that evaluate cardiac events in breast cancer patients with a prior history of cardiac disease managed with breast conservation
  • This study sought to determine the risk of cardiac morbidity and mortality in this subset of breast cancer patients

Materials and Methods

  • Early stage breast cancer patients with a pre-existing history of MI, congestive heart failure (CHF), or CAD and receiving radiotherapy as part of breast conservation treatment at the University of Pennsylvania between 1980 and 1994 were included in this retrospective analysis
  • All patients were treated with megavoltage therapy (6 - 15MV) to tangential coplanar fields followed by a boost to the tumor bed
  • Patients were stratified by laterality of disease (right- or left-sided), and data were collected on patient and tumor characteristics, treatment, baseline cardiac status, acute and late cardiac morbidity, and survival status
  • End-points included development of CAD, CHF, MI, arrhythmias, and valvular disease; other end-points included overall survival, cardiac deaths, breast cancer deaths, and deaths due to other causes

Results

  • 41 patients were included in the analysis
    • 42% (N=15) had left-sided disease
      • 87% (N=13) of left-sided disease patients received radiotherapy with tangents only
      • 13% (N=2) of left-sided disease patients received nodal radiotherapy (anterior supraclavicular field with or without a posterior axillary field)
      • 20% (N=3) of left-sided disease patients received radiation to the internal mammary nodes
    • 58% (N=26) had right-sided disease
      • 58% (N=15) of right-sided disease patients received radiotherapy with tangents only
      • 42% (N=11) of right-sided disease patients received nodal radiotherapy (anterior supraclavicular field with or without a posterior axillary field)
      • 19% (N=5) of right-sided disease patients received radiation to the internal mammary nodes
  • The median follow-up was 11.3 years for left-sided patients and 7.9 years for right-sided patients
  • The median radiation dose was 64 Gy (range 60 to 72.4)
  • other than a significantly increased age of right-sided patients, the left- and right-sided groups were similar with respect to patient and tumor characteristics, treatment, pre-existing cardiac risk factors, and pre-existing cardiac status
  • There was no difference between the 2 groups regarding development of new cardiac disease (CAD, CHF, MI, arrhythmias, valvular disease) following radiation (p=0.6)
  • There was no difference between the 2 groups in 15-year overall survival (p=0.186)
  • There was a trend toward a significantly higher proportion of cardiac deaths in the left-sided group (49% vs. 9%, p=0.08) including those secondary to MI, CHF, or CAD
  • There was a higher proportion in the right-sided group of both breast cancer deaths (31% vs. 13%) and deaths due to other causes (27% vs. 7%)

Author's Conclusions

Though overall survival was not different between the 2 patient groups, radiation treatment was associated with a higher proportion of cardiac deaths in patients with left-sided breast cancers

Clinical/Scientific Implications

Though somewhat small, this study is one of the few that have evaluated long-term morbidity and mortality in breast cancer patients with a prior history of cardiac disease undergoing radiation treatment as part of breast conservation therapy. Cardiac deaths were found to be higher in the left-sided patients, although overall survival was similar between the 2 groups. The fact that the right-sided patients were significantly older than the left-sided patients may potentially obscure any potential detriment to overall survival in left-sided patients treated with radiotherapy. Additionally, the older age of the right-sided patients could reflect a selection bias, as older patients with left-sided disease may have been steered away from radiotherapy due to concerns over cardiac complications. As this study is retrospective, it is hypothesis-generating only, and prospective data would be helpful in reducing systematic biases and allowing for more definitive conclusions.


News
Trastuzumab Ups Cardiac Risk for Older Women With Breast Cancer

Nov 16, 2012 - For older women with early-stage breast cancer, treatment with trastuzumab correlates with increased rates of heart failure and cardiomyopathy, according to a study published online Nov. 14 in the Journal of the American College of Cardiology.



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