Abstract
Purpose/ObjectivesNode-positive breast cancer patients often receive chemotherapy and regional nodal irradiation. The cardiotoxic effects of these treatments, however, may offset some of the survival benefit. Cardiac magnetic resonance (CMR) is an emerging modality to assess cardiac injury. This is a pilot trial assessing cardiac damage using CMR in patients who received anthracycline-based chemotherapy and three-dimensional conformal radiotherapy (3DCRT) regional nodal irradiation using heart constraints.Materials and MethodsNode-positive breast cancer patients (2000–2008) treated with anthracycline-based chemotherapy and 3DCRT regional nodal irradiation (including the internal mammary chain nodes) with heart ventricular constraints (V25 < 10%) were invited to participate. Cardiac tissues were contoured and analyzed separately for whole heart (pericardium) and for combined ventricles and left atrium (myocardium). CMR obtained ventricular function/dimensions, late gadolinium enhancement (LGE), global longitudinal strain (GLS), and extracellular volume fraction (ECV) as measures of cardiac injury and/or early fibrosis. CMR parameters were correlated with dose-volume constraints using Spearman correlations.ResultsFifteen left-sided and five right-sided patients underwent CMR. Median diagnosis age was 50 (32–77). No patients had baseline cardiac disease before regional nodal irradiation. Median time after 3DCRT was 8.3 years (5.2–14.4). Median left-sided mean heart dose (MHD) was 4.8 Gy (1.1–11.2) and V25 was 5.7% (0–12%). Median left ventricular ejection fraction (LVEF) was 63%. No abnormal LGE was observed. No correlations were seen between whole heart doses and LVEF, LV mass, GLS, or LV dimensions. Increasing ECV did not correlate with increased heart or ventricular doses. However, correlations between higher LV mass and ventricular mean dose, V10, and V25 were seen.ConclusionAt a median follow-up of 8.3 years, this cohort of node-positive breast cancer patients who received anthracycline-based chemotherapy and regional nodal irradiation had no clinically abnormal CMR findings. However, correlations between ventricular mean dose, V10, and V25 and LV mass were seen. Larger corroborating studies that include advanced techniques for measuring regional heart mechanics are warranted.
Highlights
The use of regional nodal irradiation (RNI) for node positive breast cancer treatment after breast conserving surgery or mastectomy improves local control and survival [1, 2]
This study aims to explore whether Cardiac magnetic resonance imaging (CMR)-demonstrated changes in perfusion, cardiac function, or cardiac anatomy correlate with the received radiation doses
Late gadolinium enhancement (LGE) and total left ventricular (LV) myocardial extracellular volume (ECV) fraction were obtained as measures of cardiac scar and/or early cardiac fibrosis [36, 37]
Summary
The use of regional nodal irradiation (RNI) for node positive breast cancer treatment after breast conserving surgery or mastectomy improves local control and survival [1, 2]. Patients with left-sided breast cancer receiving radiation have increased rates of major coronary events [9, 10] and cardiac mortality [7, 11]. Anthracyclines have been shown to increase risk of systolic dysfunction and congestive heart failure as well as subclinical cardiac changes [17,18,19]. This risk does not outweigh the survival benefit of anthracyclines [20], cardiac changes can be seen in survivors as far as 18 years or more from diagnosis [21]. The interaction of anthracyclines and radiation on cardiovascular outcomes is not fully understood, but additional cardiac risk factors have been shown to increase the absolute risk of cardiac events after radiation therapy [9]
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