- Hypofractionated radiotherapy (Hypo-RT) given concurrently with trastuzumab is not associated with excess cardiotoxicity compared with conventionally fractionated radiotherapy (Conv-RT)+trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BCa).
Why this matters
- Preclinical data suggest that trastuzumab has a radiosensitizing effect.
- Retrospective cohort comparing trastuzumab recipients treated with Hypo-RT (n=41) vs those treated with Conv-RT (n=100).
- Cardiotoxicity was assessed as a significant decline in left ventricular ejection fraction (LVEF) of ≥10% below lower limit of normal or ≥16% from baseline.
- Funding: Breast Cancer Research Foundation.
- Median follow-up was 32 (range, 13-90) months.
- Mean heart dose was 101 cGy in the Hypo-RT group and 163 cGy in Conv-RT group (P=.897).
- Baseline median LVEF: 62% (range, 50%-81%) in Hypo-RT group vs 64% (range, 51%-76%) in the Conv-RT group (P=.893).
- Final median LVEF: 60% (range, 50%-75%) in each group (P=.998).
- Significant LVEF decline: 7% in Hypo-RT group vs 5% in Conv-RT group (P=.203).
- No difference in mean heart dose in patients who developed significant LVEF decline vs patients who did not develop significant LVEF decline in the Hypo-RT (P=.427) and in Conv-RT groups (P=.354).
- Neither group developed congestive heart failure.
- Retrospective, observational, single-center design.
- Small number of patients in the Hypo-RT group.