title: Long-term cosmetic changes after breast-conserving treatment of patients with stage I-II breast cancer and included in the EORTC 'boost versus no boost' trial.
abstract: BACKGROUND
  In breast cancer treated with breast-conserving radiotherapy, the influence of the boost dose on cosmetic outcome after long-term follow-up is unknown.
  
  
  METHODS
  We included 348 patients participating in the EORTC 'boost versus no boost' mega trial with a minimum follow-up of 6 years. Digitalised pictures were analysed using specific software, enabling quantification of seven relative asymmetry features associated with different aspects of fibrosis.
  
  
  RESULTS
  After 3 years, we noted a statistically significantly poorer outcome for the boost patients for six features compared with those of the no boost patients. Up to 9 years of follow-up, results continued to worsen in the same magnitude for the both patient groups. We noted the following determinants for poorer outcome: (i) boost treatment, (ii) larger excision volumes, (iii) younger age, (iv) tumours located in the central lower quadrants of the breast and (v) a boost dose administered with photons.
  
  
  CONCLUSIONS
  A boost dose worsens the change in breast appearance in the first 3 years. Moreover, the development of fibrosis associated with whole-breast irradiation, as estimated with the relative asymmetry features, is an ongoing process until (at least) 9 years after irradiation.
authors.affiliation: Department of Radiotherapy, Medical Center, Reinier de Graaf Groep, Delft. Electronic address: immink@rdgg.nl.
authors.forename: J M
authors.initials: JM
authors.lastname: Immink
authors.affiliation: Department of Statistics, Leiden University Medical Center, Leiden.
authors.forename: H
authors.initials: H
authors.lastname: Putter
authors.affiliation: Department of Radiotherapy, Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Bartelink
authors.affiliation: Electrical and Computer Engineering INESC Porto, Faculty of Engineering, University of Porto, Porto.
authors.forename: J S
authors.initials: JS
authors.lastname: Cardoso
authors.affiliation: Department of Surgery, Champalimaud Cancer Center, Lisbon, Portugal.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cardoso
authors.affiliation: Department of Radiation Oncology, Institute Verbeeten, Tilburg.
authors.forename: M H V
authors.initials: MHV
authors.lastname: van der Hulst-Vijgen
authors.affiliation: Department of Radiotherapy, Leiden University Medical Center, Leiden.
authors.forename: E M
authors.initials: EM
authors.lastname: Noordijk
authors.affiliation: Department of Radiation Oncology, Institute Verbeeten, Tilburg.
authors.forename: P M
authors.initials: PM
authors.lastname: Poortmans
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, Utrecht.
authors.forename: C C
authors.initials: CC
authors.lastname: Rodenhuis
authors.affiliation: Department of Radiotherapy, Leiden University Medical Center, Leiden; Department of Radiotherapy, Radiotherapy Centre West, The Hague, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Struikmans
mesh_terms: D001943:Breast Neoplasms / Q000601:surgery*; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental