title: Exposure of the Heart in Breast Cancer Radiation Therapy: A Systematic Review of Heart Doses Published During 2003 to 2013.
abstract: OBJECTIVE
  Breast cancer radiation therapy cures many women, but where the heart is exposed, it can cause heart disease. We report a systematic review of heart doses from breast cancer radiation therapy that were published during 2003 to 2013.
  
  
  METHODS
  Eligible studies were those reporting whole-heart dose (ie, dose averaged over the whole heart). Analyses considered the arithmetic mean of the whole-heart doses for the CT plans for each regimen in each study. We termed this "mean heart dose."
  
  
  RESULTS
  In left-sided breast cancer, mean heart dose averaged over all 398 regimens reported in 149 studies from 28 countries was 5.4 Gy (range, <0.1-28.6 Gy). In regimens that did not include the internal mammary chain (IMC), average mean heart dose was 4.2 Gy and varied with the target tissues irradiated. The lowest average mean heart doses were from tangential radiation therapy with either breathing control (1.3 Gy; range, 0.4-2.5 Gy) or treatment in the lateral decubitus position (1.2 Gy; range, 0.8-1.7 Gy), or from proton radiation therapy (0.5 Gy; range, 0.1-0.8 Gy). For intensity modulated radiation therapy mean heart dose was 5.6 Gy (range, <0.1-23.0 Gy). Where the IMC was irradiated, average mean heart dose was around 8 Gy and varied little according to which other targets were irradiated. Proton radiation therapy delivered the lowest average mean heart dose (2.6 Gy, range, 1.0-6.0 Gy), and tangential radiation therapy with a separate IMC field the highest (9.2 Gy, range, 1.9-21.0 Gy). In right-sided breast cancer, the average mean heart dose was 3.3 Gy based on 45 regimens in 23 studies.
  
  
  CONCLUSIONS
  Recent estimates of typical heart doses from left breast cancer radiation therapy vary widely between studies, even for apparently similar regimens. Maneuvers to reduce heart dose in left tangential radiation therapy were successful. Proton radiation therapy delivered the lowest doses. Inclusion of the IMC doubled typical heart dose.
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom. Electronic address: carolyn.taylor@ctsu.ox.ac.uk.
authors.forename: Carolyn W
authors.initials: CW
authors.lastname: Taylor
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Banbury, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Macaulay
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Reshma
authors.initials: R
authors.lastname: Jagsi
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.
authors.forename: Frances
authors.initials: F
authors.lastname: Duane
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Darby
mesh_terms: D066126:Cardiotoxicity / Q000209:etiology / Q000517:prevention & control; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D015182:Lymphatic Irradiation / Q000706:statistics & numerical data; D058958:Organs at Risk / Q000528:radiation effects; D061766:Proton Therapy / Q000706:statistics & numerical data; D011829:Radiation Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000706:statistics & numerical data; D000069584:Unilateral Breast Neoplasms / Q000532:radiotherapy*