Applying global longitudinal strain in assessing cardiac dysfunction after radiotherapy among breast cancer patients: a systemic review and meta-analysis

Purpose Radiation-induced heart disease (RIHD) has cost severe health burden to breast cancer patients. However, early thoracic radiotherapy (RT)-induced cardiac damage was hard to detect through traditional echocardiography. Therefore, we conducted this systemic review and meta-analysis to evaluate the changes of GLS, an innovative echocardiographic measurement, after thoracic radiotherapy. Methods We searched PubMed, Embase and Web of Science using the key words “breast cancer”, “radiotherapy” and “GLS” for relevant papers. Studies covered the difference of GLS change before and after radiotherapy were included, and the standard mean difference (SMD) and its standard error were extracted and pooled using a random-effects or fixed-effects model. Results A total of 11 studies comprising 18 comparisons were identified, and 1808 patients were involved. The pooled SMD of GLS before and within 6-week after radiotherapy was 0.48 (95% CI 0.34–0.61, p < 0.01), and the pooled long-term changes in GLS (over 6-month after radiotherapy) was 0.46 (95% CI 0.20–0.72, p < 0.01). No obvious publication bias were observed. Conclusion Breast cancer patients are facing greater risk of RIHD since they presented a better survival rate and longer life expectancy with the popularization of radiotherapy. GLS might be useful in capturing minimal cardiac changes shortly after radiotherapy or during long-term follow up visit.