title: Whole breast proton irradiation for maximal reduction of heart dose in breast cancer patients.
abstract: OBJECTIVE
  In left-sided breast cancer radiotherapy, tangential intensity modulated radiotherapy combined with breath-hold enables a dose reduction to the heart and left anterior descending (LAD) coronary artery. Aim of this study was to investigate the added value of intensity modulated proton therapy (IMPT) with regard to decreasing the radiation dose to these structures.
  
  
  METHODS
  In this comparative planning study, four treatment plans were generated in 20 patients: an IMPT plan and a tangential IMRT plan, both with breath-hold and free-breathing. At least 97 % of the target volume had to be covered by at least 95 % of the prescribed dose in all cases. Specifically with respect to the heart, the LAD, and the target volumes, we analyzed the maximum doses, the mean doses, and the volumes receiving 5-30 Gy.
  
  
  RESULTS
  As compared to IMRT, IMPT resulted in significant dose reductions to the heart and LAD-region even without breath-hold. In the majority of the IMPT cases, a reduction to almost zero to the heart and LAD-region was obtained. IMPT treatment plans yielded the lowest dose to the lungs.
  
  
  CONCLUSIONS
  With IMPT the dose to the heart and LAD-region could be significantly decreased compared to tangential IMRT with breath-hold. The clinical relevance should be assessed individually based on the baseline risk of cardiac complications in combination with the dose to organs at risk. However, as IMPT for breast cancer is currently not widely available, IMPT should be reserved for patients remaining at high risk for major coronary events.
authors.affiliation: Radiotherapy Centre West, Lijnbaan 32, 2501 CK, The Hague, The Netherlands, m.mast@mchaaglanden.nl.
authors.forename: Mirjam E
authors.initials: ME
authors.lastname: Mast
authors.forename: Eline J
authors.initials: EJ
authors.lastname: Vredeveld
authors.forename: Herman M
authors.initials: HM
authors.lastname: Credoe
authors.forename: Jaap
authors.initials: J
authors.lastname: van Egmond
authors.forename: Mark W
authors.initials: MW
authors.lastname: Heijenbrok
authors.forename: Eugen B
authors.initials: EB
authors.lastname: Hug
authors.forename: Patrick
authors.initials: P
authors.lastname: Kalk
authors.forename: Loes M L
authors.initials: LM
authors.lastname: van Kempen-Harteveld
authors.forename: Erik W
authors.initials: EW
authors.lastname: Korevaar
authors.forename: Hans Paul
authors.initials: HP
authors.lastname: van der Laan
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Langendijk
authors.forename: Hans J E
authors.initials: HJ
authors.lastname: Rozema
authors.forename: Anna L
authors.initials: AL
authors.lastname: Petoukhova
authors.forename: Jacobus M
authors.initials: JM
authors.lastname: Schippers
authors.forename: Henk
authors.initials: H
authors.lastname: Struikmans
authors.forename: John H
authors.initials: JH
authors.lastname: Maduro
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods