Troponin T-release associates with cardiac radiation doses during adjuvant left-sided breast cancer radiotherapy.

Tanja Skyttä,Eeva Boman,Suvi Tuohinen,Vesa Virtanen,Pirkko-Liisa Kellokumpu-Lehtinen,Pekka Raatikainen

doi:10.1186/s13014-015-0436-2

Abstract

BackgroundAdjuvant radiotherapy (RT) for left-sided breast cancer increases cardiac morbidity and mortality. For the heart, no safe radiation threshold has been established. Troponin T is a sensitive marker of myocardial damage. Our aim was to evaluate the effect of left-sided breast cancer RT on serum high sensitivity troponin T (hscTnT) levels and its association with cardiac radiation doses and echocardiographic parameters.MethodsA total of 58 patients with an early stage, left-sided breast cancer or ductal carcinoma in situ (DCIS) who received adjuvant breast RT without prior chemotherapy were included in this prospective, non-randomized study. Serum samples were taken before, during and after RT. An increase of hscTnT >30 % was predefined as significant. A comprehensive 2D echocardiograph and electrocardiogram (ECG) were performed before and after RT. Dose-volume histograms (DVHs) were generated for different cardiac structures.ResultsThe hscTnT increased during RT from baseline in 12/58 patients (21 %). Patients with increased hscTnT values (group A, N = 12) had significantly higher radiation doses for the whole heart (p = 0.02) and left ventricle (p = 0.03) than patients without hscTnT increase (group B, N = 46). For the left anterior descending artery (LAD), differences between groups A and B were found in volumes receiving 15 Gy (p = 0.03) and 20 Gy (p = 0.03) Furthermore, after RT, the interventricular septum thickened (p = 0.01), and the deceleration time was prolonged (p = 0.008) more in group A than in group B.ConclusionsThe increase in hscTnT level during adjuvant RT was positively associated with the cardiac radiation doses for the whole heart and LV in chemotherapy-naive breast cancer patients. Whether these acute subclinical changes increase the risk of excessive long-term cardiovascular morbidity or mortality, will be addressed in the follow-up of our patients.

Highlights

Adjuvant radiotherapy (RT) for left-sided breast cancer increases cardiac morbidity and mortality
We demonstrated that high sensitivity cardiac troponin T levels increased during the whole breast adjuvant RT in every fifth patient
*p value between groups cardiac structures received more radiation. These findings show, that increasing cardiac doses associate with myocyte damage measured by hscTnT release

Summary

Introduction

Adjuvant radiotherapy (RT) for left-sided breast cancer increases cardiac morbidity and mortality. Troponin T is a sensitive marker of myocardial damage. Our aim was to evaluate the effect of left-sided breast cancer RT on serum high sensitivity troponin T (hscTnT) levels and its association with cardiac radiation doses and echocardiographic parameters. Left-sided RT, especially, has been shown to induce excess cardiovascular mortality and morbidity [1,2,3,4]. Darby et al showed that the risk of major cardiac events in patients with left-sided breast cancer. Radiation induced cardiac changes have been demonstrated with echocardiographic strain rate imaging [5], myocardial perfusion scintigraphy [6, 7] and single photon emission tomography [8].

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