Breast Cancer

PV 01 - Poster Viewing Q&A - Session 1

SU_9_2089 - Risk of Heart Failure after Radiotherapy in Women with HER2+ Breast Cancer Treated with Trastuzumab

Sunday, September 15
1:15 PM - 2:30 PM
Location: ASTRO Innovation Hub

Risk of Heart Failure after Radiotherapy in Women with HER2+ Breast Cancer Treated with Trastuzumab
K. Aziz1, S. Nowsheen2, J. Herrmann3, K. J. Ruddy4, and R. W. Mutter5; 1Mayo Clinic Medical Scientist Training Program, Rochester, MN, 2Mayo Clinic, Rochester, MN, 3Department of Cardiology, Mayo Clinic, Rochester, MN, 4Division of Medical Oncology, Mayo Clinic, Rochester, MN, 5Department of Radiation Oncology, Mayo Clinic, Rochester, MN

Purpose/Objective(s): We conducted a case-cohort study to analyze the effect of heart exposure to ionizing radiation on the subsequent risk of heart failure (HF) in women with human epidermal growth factor receptor 2 (HER2+) breast cancer treated with trastuzumab and radiation therapy (RT).

Materials/Methods: Between 2000 and 2015, 731 patients were treated with trastuzumab at our institution for HER2+ breast cancer, among whom 480 had documentation of left ventricular ejection fraction (LVEF) before and after starting treatment. Males (n=40) and patients with a clinical diagnosis of HF or LVEF≤53 prior to trastuzumab initiation (n=32) were excluded. Of the 408 remaining patients, 252 received adjuvant breast/chest wall photon RT, median dose of 5000cGy in 25 fractions. 65 of the 252 had CT-based treatment planning cardiac dosimetry accessible for analysis, including 15 women with clinically diagnosed HF and 50 controls. 6 patients in the control group and 2 patients in the HF group also received nodal RT.

Results: The overall median mean heart dose was 223.8 cGy (range, 15.9 to 1579.4 cGy). Baseline EF was the only factor associated with a higher rate of HF (table 1). The heart mean, maximum, V500cGy, and V2000cGy were not associated with higher rates of HR, nor did other clinical factors such as anthracycline therapy, obesity, age, or hypertension. Mean and maximum dose delivered to heart was comparable between the two groups.

Conclusion:

Exposure of the heart to radiation during RT for breast cancer did not significantly increase the rate of heart failure. Further investigation into predictors of HF in patients receiving trastuzumab are needed to optimize surveillance and preventative strategies. Table: 1
Criteria No heart failure (n=50) Heart failure (n=15) Total (n=65) p value
Anthracycline use (%, n) 80% (n=40) 60% (n=9) 75% (n=49) 0.17
EF prior to trastuzumab therapy (median, range) 64 (53-76) 61 (55-68) 63 (53-76) 0.01
Radiation to both chest walls (%, n) 6% (n=3) 13.3% (n=2) 7.7% (n=5) 0.33
Radiation to left chest wall (%, n) 68% (n=34) 40% (n=6) 61.5% (n=40) 0.07
Radiation to right chest wall (%, n) 26% (n=13) 46.7% (n=7) 30.8% (n=20) 0.20
Mean dose of radiation to heart (median (cGY), range) 245.6 (32.2-1264.5) 206.8 (15.9-1579.4) 223.8 (15.9-1579.4) 0.70
Max dose of radiation to heart (median (cGY), range) 3219.8 (256-5928.7) 3454.1 (145.2-5231.8) 3287 (145.2-5928.7) 0.57
Heart v_500 (median (cc), range) 41.7 (0-521.2) 37.1 (0-411.8) 38.2 (0-521.2) 0.80
Heart v_2000 (median (cc), range) 2.5 (0-119) 2.1 (0-118.5) 2.5 (0-119) 0.59

Author Disclosure: K. Aziz: None. S. Nowsheen: None. K.J. Ruddy: Stock; Pfizer, Merck. R.W. Mutter: Research Grant; ASTRO.

Khaled Aziz, MS, BS

Mayo Clinic Alix School of Medicine

Biography:
Khaled Aziz is a MSTP student at Mayo Clinic school of medicine. His clinical research focuses on toxicity outcomes after radiation therapy in various malignancies and doctoral dissertation focused on chromosomal instability. Previously, he studied oxidatively induced complex DNA damage as an undergraduate student at East Carolina University. He was previously employed as a research technologist at Johns Hopkins Department of Radiation Oncology studying epithelial mesenchymal transition and mechanisms of radiation sensitization. His passion outside of aademics are running and soccer.

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