Re: Coronary Artery Findings After Left-Sided Compared With Right-Sided Radiation Treatment for Early-Stage Breast Cancer

Intl J Rad Oncol Biol Phys, Volume 63, Issue 1, Pages 214-223 (1
September 2005)

The incidence and functional consequences of RT-associated cardiac
perfusion defects

Portions of this work were presented at the 44th Annual Meeting of the
American Society for Therapeutic Radiology and Oncology, New Orleans,
LA, October 6-10, 2002, and at the 45th Annual Meeting of American
Society for Therapeutic Radiology and Oncology, Salt Lake City, UT,
October 18-23, 2003.

Lawrence B. Marks, M.D. , Xiaoli Yu, M.D. , Robert G. Prosnitz, M.D. ,
Su-Min Zhou, Ph.D. , Patricia H. Hardenbergh, M.D. , Michael Blazing,
M.D.?, Donna Hollis, M.S.?, Pehr Lind, M.D., Ph.D. , Andrea Tisch,
B.A. , Terence Z. Wong, M.D., Ph.D.§, Salvador Borges-Neto, M.D.§

Received 24 August 2004; received in revised form 10 January 2005;
accepted 18 January 2005. published online 31 March 2005.

Purpose: Radiation therapy (RT) for left-sided breast cancer has been
associated with cardiac dysfunction. We herein assess the temporal
nature and volume dependence of RT-induced left ventricular perfusion
defects and whether these perfusion defects are related to changes in
cardiac wall motion or alterations in ejection fraction.

Methods: From 1998 to 2001, 114 patients were enrolled onto an IRB-
approved prospective clinical study to assess changes in regional and
global cardiac function after RT for left-sided breast cancer.
Patients were imaged 30 to 60 minutes after injection of technetium
99m sestamibi or tetrofosmin. Post-RT perfusion scans were compared
with the pre-RT studies to assess for RT-induced perfusion defects as
well as functional changes in wall motion and ejection fraction. Two-
tailed Fisher's exact test and the Cochran-Armitage test for linear
trends were used for statistical analysis.

Results: The incidence of new perfusion defects 6, 12, 18, and 24
months after RT was 27%, 29%, 38%, and 42%, respectively. New defects
occurred in approximately 10% to 20% and 50% to 60% of patients with
less than 5%, and greater than 5%, of their left ventricle included
within the RT fields, respectively (p = 0.33 to 0.00008). The rates of
wall motion abnormalities in patients with and without perfusion
defects were 12% to 40% versus 0% to 9%, respectively; p values were
0.007 to 0.16, depending on the post-RT interval.

Conclusions: Radiation therapy causes volume-dependent perfusion
defects in approximately 40% of patients within 2 years of RT. These
perfusion defects are associated with corresponding wall-motion
abnormalities. Additional study is necessary to better define the long-
term functional consequences of RT-induced perfusion defects.

Keywords: Radiotherapy, Breast cancer, Myocardial perfusion, SPECT
Department of Radiation Oncology, Duke University Medical Center,
Durham, North Carolina, USA

? Department of Cardiology, Duke University Medical Center, Durham,
North Carolina, USA

? Department of Biostatistics, Duke University Medical Center, Durham,
North Carolina, USA

§ Department of Radiology, Duke University Medical Center, Durham, NC

Reprint requests to: Lawrence B. Marks, M.D., Department of Radiation
Oncology, Box 3085

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