title: Troponin T-release associates with cardiac radiation doses during adjuvant left-sided breast cancer radiotherapy.
abstract: BACKGROUND
  Adjuvant 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.
  
  
  METHODS
  A 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.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: Department of Oncology and School of Medicine, Tampere University Hospital, University of Tampere, 33521, Tampere, Finland. tanja.skytta@pshp.fi.
authors.forename: Tanja
authors.initials: T
authors.lastname: Skyttä
authors.affiliation: Heart Center Co and School of Medicine, University of Tampere, Tampere University Hospital, Tampere, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Tuohinen
authors.affiliation: Department of Oncology, Tampere University Hospital and Department of Medical Physics, Medical Imaging Center and Hospital Pharmacy, Tampere, Finland.
authors.forename: Eeva
authors.initials: E
authors.lastname: Boman
authors.affiliation: Heart Center Co and School of Medicine, University of Tampere, Tampere University Hospital, Tampere, Finland.
authors.forename: Vesa
authors.initials: V
authors.lastname: Virtanen
authors.affiliation: Department of Medicine, Central Finland Health Care District and University of Eastern Finland, Jyväskylä, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Raatikainen
authors.affiliation: Department of Oncology and School of Medicine, Tampere University Hospital, University of Tampere, 33521, Tampere, Finland.
authors.forename: Pirkko-Liisa
authors.initials: PL
authors.lastname: Kellokumpu-Lehtinen
mesh_terms: D000368:Aged; D015415:Biomarkers; D001943:Breast Neoplasms / Q000532:radiotherapy*; D018270:Carcinoma, Ductal, Breast / Q000532:radiotherapy*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000532:radiotherapy*; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D008408:Mastectomy; D015412:Mastectomy, Segmental; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D058958:Organs at Risk; D011446:Prospective Studies; D011832:Radiation Injuries / Q000097:blood* / Q000000981:diagnostic imaging / Q000209:etiology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects*; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D061089:Radiotherapy, Image-Guided; D012680:Sensitivity and Specificity; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D020107:Troponin T; D020097:Natriuretic Peptide, Brain