Myocardial damage on SPECT imaging among patients treated with radiotherapy for left-sided breast cancer: Systematic review with meta-analysis and narrative synthesis.

Purpose: With advancements in radiation oncology techniques, the use of radiation therapy (RT) as a treatment modality for cancer has been steadily increasing. Incidental radiation exposure to surrounding tissue during breast cancer treatment has been known to cause myocardial damage, the extent of which can be detected with single-photon emission computed tomography (SPECT) perfusion studies. We undertook a systematic review and meta-analysis to investigate the impact of RT on myocardial perfusion. Methods: A systematic review of the literature was conducted to identify 17 studies, of which 4 were included in this meta-analysis and 13 were included in the narrative synthesis. Results: The incidence of post-radiation cardiac perfusion defects on SPECT was significantly higher in patients who received RT for left-sided breast cancer compared to those who had RT for right-sided breast cancer (OR=3.10, 95% CI 1.35-7.08, p=0.007). Conclusion: In patients who undergo RT for left-sided breast cancer, the incidence of post-radiation cardiac perfusion defects on SPECT is higher compared to patients who undergo RT for right-sided breast cancer.