Objective(s):Radiation therapy for breast cancer can induce myocardial capillary injury and increase cardiovascular morbidity and mortality. A prospective cohort was conducted to study the prevalence of myocardial perfusion abnormalities following radiation therapy of left-sided breast cancer patients as compared to those with right–sided cancer.
Methods:To minimize potential confounding factors, only those patients with low 10-year risk of coronary artery disease (based on Framingham risk scoring) were included. All patients were initially treated by modified radical mastectomy and then were managed by postoperative 3D Conformal Radiation Therapy (CRT) to the surgical bed with an additional 1-cm margin, delivered by 46-50 Gy (in 2 Gy daily fractions) over a 5-week course. The same dose-adjusted chemotherapy regimen (including anthracyclines, cyclophosphamideand taxol) was given to all patients. Six month after radiation therapy, all patients underwent cardiac SPECT for the evaluation of myocardial perfusion.
Results:A total of 71 patients with a mean age of 45.3±7.2 years [35 patients with left-sided breast cancer (exposed) and 36 patients with right-sided cancer (controls)] were enrolled. Dose-volume histogram (DVH) [showing the percentage of the heart exposed to >50% of radiation] was significantly higher in patients with left-sided breast cancer. Visual interpretation detected perfusion abnormalities in 42.9% of cases and 16.7% of controls (p: 0.02, Odds ratio: 1.46). In semiquantitative segmental analysis, only apical (28.6% versus 8.3%, p: 0.03) and anterolateral (17.1% versus 2.8%: P: 0.049) walls showed significantly reduced myocardial perfusion in the exposed group. Summed Stress Score (SSS) of >3 was observed in twelve cases (34.3%), while in five of the controls (13.9%), (Odds ratio: 1.3). There was no significant difference between the gro