The effect of breast irradiation on cardiac disease in women enrolled on BCIRG-001 at 10 year follow-up
Menée à partir de données portant sur 746 patientes atteintes d'un cancer du sein de stade précoce avec envahissement ganglionnaire et incluses dans un essai de phase III comparant deux chimiothérapies adjuvantes (durée de suivi : 10 ans), cette étude analyse sur le long terme la toxicité cardiaque d'une irradiation mammaire
Purpose/Objective(s) : Radiation therapy (RT) for breast cancer has been shown to increase the risk of long term cardiac morbidity. This study investigated cardiac toxicity associated with breast RT at 10 year follow-up in BCIRG-001, a phase III trial comparing adjuvant anthracycline chemotherapy (fluorouracil, doxorubicin, and cyclophosphamide; FAC) with anthracycline-taxane chemotherapy (docetaxel, doxorubicin, and cyclophosphamide; TAC) in women with lymph node (LN) positive early breast cancer. Materials/Methods : Prospective data from all 746 patients in the control arm (FAC) of BCIRG-001 at 10 year follow-up were obtained from Project Data Sphere. Cardiac toxicities examined included myocardial infarction (MI), heart failure (HF), arrhythmias, and relative and absolute left ventricular ejection fraction (LVEF) decrease of >20% from baseline. Toxicities were compared between patients who received RT versus no RT, left sided RT versus no RT, and internal mammary nodal (IMN) RT versus no RT. Results : Of the 746 patients, 559 (75%) received RT to a median dose of 50 Gy. MI occurred in 3(0.5%) RT patients versus 6(3%) no RT patients (p=0.01). HF was seen in 15 (2.7%) RT patients versus 3 (1.6%) no RT patients (p=0.6). Among these, 35 (18%) RT patients had a LVEF relative decrease of >20% baseline versus 7 (10%) who did not receive RT (p=0.1). Arrhythmias were more common in RT patients (3.2%) versus no RT (0%) patients (p=0.01). On univariable and multivariable analysis HF was not significantly associated with RT, and MI was negatively associated with RT. Conclusion : In this retrospective analysis of prospective toxicity outcomes, there is an increased risk of arrhythmias but no clear evidence of significantly increased risk of MI or heart failure at 10 years in lymph node positive women treated with breast RT and uniform adjuvant doxorubicin-based chemotherapy. Given the low incidence of these outcomes, studies with larger numbers are needed to confirm our findings.