No Acute Changes in LVEF Observed With Concurrent Trastuzumab and Breast Radiation With Low Heart Doses.

Introduction/background: Treatment for HER2-postitive breast cancer often includes trastuzumab, breast/chest wall (CW) radiation (RT), and anthracyclines, all of which have cardiac toxicity. We aimed to evaluate the relationship between heart dose and acute left ventricular ejection fraction (LVEF) changes in patients who received concurrent trastuzumab and breast/CW RT with and without anthracycline use.

Patients And Methods: We retrospectively reviewed all nonmetastatic breast cancer patients from 2008 to 2015 who received concurrent trastuzumab and breast/CW RT. Baseline LVEF was compared with the LVEF closest to treatment completion as well as with the lowest post-treatment LVEF. LVEF changes were correlated with laterality, heart dosimetric parameters, and doxorubicin use.

Results: Eighty-eight patients were included in our analysis. The median follow-up was 45 months. Forty-one patients were right-sided and 47 left-sided. Thirty-one patients received doxorubicin, 16 right-sided and 15 left-sided. Mean heart dose was 1.10 Gy and 3.63 Gy for right- and left-sided patients, respectively (P < .001). In the entire cohort, a significant LVEF decrease of 3.0% was observed pre- and post-treatment. There was a significant effect of doxorubicin (P = .013) and a nonsignificant effect of RT laterality (P = .088) on LVEF change. The test of interaction between doxorubicin and laterality was not significant (P = .90). No significant association was found between LVEF change and heart dosimetric parameters, including percent volume of heart receiving 5 Gy (V5), 10 Gy (V10), 20 Gy (V20), and 45 Gy (V45), and maximum dose. Similar results were found when baseline LVEF was compared with the lowest post-treatment LVEF.

Conclusion: With cardiac doses < 4 Gy, declines in LVEF were not related to tumor laterality or heart dosimetric parameters. Statistically significant LVEF decreases were mainly attributed to doxorubicin.