Myocardial perfusion imaging in breast cancer patients treated with or without post-mastectomy radiotherapy
Introduction
Radiotherapy in breast cancer has, in some studies, been associated with an increased risk of cardiovascular mortality, which has been suggested to be caused by accelerated atherosclerosis in irradiated coronary arteries [6], [18], [20], [23], [34], [35]. Some of this mortality is believed to be a result of sub-optimal radiotherapy techniques [27]. Nevertheless, even contemporary techniques include anterior parts of the heart, such as the anterior interventricular branch of left coronary artery, in the treatment volume [9], [22]. The clinical impact of this is difficult to assess, partly because the morphology of coronary artery disease following radiation is no different from that of spontaneous atherosclerosis and, therefore, can not be diagnosed specifically [38].
Myocardial perfusion scintigraphy is recognized as a reliable non-invasive approach for the assessment of regional myocardial perfusion [24], [25], and has previously been used to evaluate the relation between radiotherapy and coronary artery disease [4], [5], [10], [11], [13], [14], [15], [28], [29], [37]. If a given radiotherapy technique causes damage to the coronary vessels, one would expect an increased prevalence of perfusion defects in irradiated patients compared with non-irradiated patients, and these defects would be located in the irradiated region of the heart.
The aim of this study was to assess the occurrence and location of abnormal regional myocardial perfusion at rest and during stress in left-sided mastectomized patients, randomized to treatment with or without postoperative radiotherapy according to the guidelines from the Danish Breast Cancer Cooperative Group (DBCG).
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Patients
This study includes 17 recurrence-free patients, who had been randomized in the DBCG 82b and 82c trials, conducted from 1982 to 1990. The design and results of the trial have been described previously [2], [8], [30], [31], [32]. In brief, mastectomized high-risk breast cancer patients were randomized to adjuvant systemic treatment, with or without postoperative irradiation. Pre- and peri-menopausal women were randomized to post-mastectomy radiotherapy plus 600 mg/m2 cyclophosphamide, 40 mg/m2
Medical history
The median age was 59 years (range, 47–75 years), and the patients had been followed for a median of 7.9 years (range, 6.0–12.2 years). Ten patients received systemic treatment plus radiotherapy (RT-group), and seven received systemic treatment alone (no-RT group). The systemic treatment, age at scintigraphy and length of follow-up for the individual patients are given in Table 1. One patient (no. 13) had known paroxystic tachycardia not requiring treatment, and another patient (no. 12) was on
Discussion
Several studies have evaluated late cardiac complications after radiotherapy using myocardial scintigraphy. Most of these studies are dealing with patients irradiated for Hodgkin's disease using treatment techniques that include a large part of the heart to a total dose of 30 Gy or more, and the results are contradictory [4], [10], [11], [13], [28], [29], [37]. Irradiation for breast cancer differs substantially from irradiation in Hodgkin's disease, as the clinical target in breast cancer only
Conclusion
The present study does not indicate that the radiotherapy technique used in the DBCG 82b and 82c trials causes IHD. However, the small number of patients does not allow strong conclusions to be drawn.
Acknowledgements
Inger Højris was supported by grants from the Danish Cancer Society, Dr Agnethe Løvgreens Legat and the Clinical Research Unit at the Oncology Center, Aarhus University Hospital. Niels Peter Rønnow Sand was supported by grants from the Danish Heart Foundation and the Institution of Experimental Clinical Research, Aarhus University Hospital.
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2022, Seminars in Nuclear MedicineCitation Excerpt :However, as this retrospective study only included 17 patients with varying baseline cardiovascular risk factors, systemic therapies and radiotherapeutic treatments, long-term follow-up is necessary to assess the predictive value of this finding for developing radiation-induced CAD.108 Nevertheless, a study performed by Hojris and colleagues in nine patients with left-sided breast cancer and seven controls more than 8 years after radiotherapy using en face electrons and the same tracer as Gyenes and colleagues, did not show a significant difference in perfusion defects on MPS (SPECT) between irradiated women between 1982 and 1990 and non-irradiated women (40% and 57% respectively).94 Moreover, the perfusion defects that were seen in the irradiated patient group were not located in the radiation field/exposed heart volume.94
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2007, Cancer Treatment ReviewsCitation Excerpt :Preliminary data suggest that these defects tend to persist at 3–5 years of follow-up; additionally new defects may occur in a significant percentage of patients with normal MPI at 6–24 months after irradiation.106 Results of retrospective studies with longer follow-up are more contradictory: a significant increase in the rate of myocardial perfusion defects was seen in two studies,29,41 but not in three others.67,72,107 Demonstrated defects tend, however, to follow the pattern of radiotherapy fields and localize in the anterior/apical regions of the heart.29,68,89,105