Key result
Concurrent trastuzumab and hypofractionated radiotherapy resulted in a 7% rate of significant asymptomatic LVEF decline, which was not significantly different from the 5% rate with conventional radiotherapy.
Why the study?
Data are limited on acute cardiotoxicity with concurrent trastuzumab and hypofractionated radiotherapy, which is now standard of care for whole breast irradiation.
Does concurrent trastuzumab and hypofractionated radiotherapy increase acute cardiotoxicity compared to conventionally fractionated radiotherapy in HER2-positive breast cancer patients?
Cohort (n=141)
No
Does concurrent trastuzumab and hypofractionated radiotherapy increase acute cardiotoxicity compared to conventionally fractionated radiotherapy in HER2-positive breast cancer patients?
Absolute Event Rate: 7% vs 5%
p-value: p=0.203
Concurrent administration of trastuzumab and hypofractionated radiotherapy in HER2-positive breast cancer patients is associated with a low rate of acute asymptomatic LVEF decline (7%), similar to conventional radiotherapy.
Supports comparable acute cardiotoxicity with hypofractionated radiotherapy during trastuzumab; leaves open need for randomized confirmation in HER2-positive breast cancer.
Purpose: Radiotherapy for patients with non-metastatic human epidermal growth factor receptor 2 (HER2) positive breast cancer is commonly administered concurrently with adjuvant trastuzumab. However, there is limited data on the use of concurrent trastuzumab and hypofractionated radiotherapy (Hypo-RT), which is now standard of care for the majority of women receiving whole breast irradiation. In this study, we compared acute cardiotoxicity rates in HER2-positive breast cancer patients treated with concurrent trastuzumab and Hypo-RT or conventionally fractionated radiotherapy (Conv-RT). Methods: We performed a review of our institutional database to identify HER2-positive breast cancer patients treated with trastuzumab and Hypo-RT or Conv-RT from 2005 to 2018 who underwent serial cardiac Left Ventricular Ejection Fraction (LVEF) evaluation. Decrease in LVEF was assessed by either echocardiography (ECHO) or multiple gated acquisition (MUGA) scan performed at baseline and every 3 months during trastuzumab therapy. Significant LVEF decline was defined as an absolute decrease in LVEF of ≥10% below the lower limit of normal or ≥16% from baseline value. Results: We identified 41 patients treated with Hypo-RT and 100 patients treated with Conv-RT. Median follow-up was 32 months (range, 13-90 months). Baseline median LVEF was 62% (range, 50-81%) in Hypo-RT group and 64% (range, 51-76%) in Conv-RT group (p=0.893). Final median LVEF was 60% (range, 50-75%) in both groups. Three patients (7%) in Hypo-RT and five (5%) in Conv-RT group developed significant asymptomatic LVEF decline (p=0.203). There was no significant difference in mean heart dose in patients who developed significant asymptomatic LVEF decline versus those who did not in Hypo-RT (p=0.427) and Conv-RT (p=0.354) groups. No symptomatic congestive heart failure was reported in either group. Conclusions: The rate of asymptomatic LVEF decline in patients receiving concurrent trastuzumab and Hypo-RT was low (7%) and was similar to the rate observed in patients receiving Conv-RT. Longer follow-up is warranted to assess late cardiotoxicity.
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Sayan et al. (2019) conducted a cohort in HER2-positive breast cancer (n=141). Hypofractionated radiotherapy (Hypo-RT) with concurrent trastuzumab vs. Conventionally fractionated radiotherapy (Conv-RT) with concurrent trastuzumab was evaluated on Significant asymptomatic LVEF decline (≥10% below lower limit of normal or ≥16% from baseline) (p=0.203). Concurrent trastuzumab and hypofractionated radiotherapy resulted in a 7% rate of significant asymptomatic LVEF decline, which was not significantly different from the 5% rate with conventional radiotherapy.
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