Myocardial perfusion changes in patients irradiated for left-sided breast cancer and correlation with coronary artery distribution.
OBJECTIVE
To evaluate postradiation regional heart perfusion changes with single photon emission tomography (SPECT) myocardial perfusion imaging in 69 patients treated with tangential photon beams radiation therapy (RT) for left-sided breast cancer. To correlate SPECT changes with percent irradiated left ventricle (LV) volume and risk factors for coronary artery disease (CAD).


METHODS
Rest SPECT of the LV was acquired pre-RT and at 6-month intervals post-RT. The extent of defects (%) with a severity > 1.5 standard deviations below the mean was quantitatively analyzed for the distributions of the left anterior descending (LAD) artery, left circumflex (LCX) artery, and right coronary artery (RCA) based on computer assisted polar map reconstruction (i.e., bull's-eye-view). Changes in perfusion were correlated with percent irradiated LV receiving > 25 Gy (range 0-32%). Data on patient- and treatment-related factors were collected prospectively (e.g., cardiac premorbidity, risk factors for CAD, chemotherapy, and hormonal treatment).


RESULTS
In the LAD distribution, there were increased perfusion defects at 6 months (median 11%; interquartile range 2-23) compared with baseline (median 5%; interquartile range 1-14) (p < 0.001). There were no increases in perfusion defects in the LCX or RCA distributions. In multivariate analysis, the SPECT perfusion changes in the LAD distribution at 6 months were independently associated with percent irradiated LV (p < 0.001), hormonal therapy (p = 0.005), and pre-RT hypercholesterolemia (p = 0.006). The SPECT defects in the LAD distribution at 12 and 18 months were not statistically different from those at 6 months. The perfusion defects in the LAD distribution were limited essentially to the regions of irradiated myocardium.


CONCLUSIONS
Tangential photon beam RT in patients with left-sided breast cancer was associated with short-term SPECT defects in the vascular distribution corresponding to the radiation portals. Factors related to the extent of perfusion defects included the percent irradiated LV, hormonal treatment, and pre-RT hypercholesterolemia.
Lind
Pehr A
PA
Departmentsof Radiation Oncology, Duke University, Durham, NC, USA. Pehr.Lind@abc.se
Pagnanelli
Robert
R
Marks
Lawrence B
LB
Borges-Neto
Salvador
S
Hu
Caroline
C
Zhou
Su Min
SM
Light
Kim
K
Hardenbergh
Patricia H
PH
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D003326:Coronary Circulation / Q000502:physiology / Q000528:radiation effects*; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D003331:Coronary Vessels / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008297:Male; D015412:Mastectomy, Segmental; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D015899:Tomography, Emission-Computed, Single-Photon; D016277:Ventricular Function, Left