title: Radiation-induced fibrosis in the boost area after three-dimensional conformal radiotherapy with a simultaneous integrated boost technique for early-stage breast cancer: A multivariable prediction model.
abstract: To develop a multivariable prediction model for the risk of grade⩾2 fibrosis in the boost area after breast conserving surgery (BCS) followed by three-dimensional conformal radiotherapy (RT) with a simultaneous integrated photon boost (3D-CRT-SIB), five years after RT.
  
  
  
  This prospective cohort study included 1,030 patients treated with RT for breast cancer (stage 0-III), after BCS. Data regarding physician-rated fibrosis and dose-volume parameters were available in 546 patients. A multivariable logistic regression model for grade⩾2 fibrosis was generated.
  
  
  
  At 5years, grade⩾2 fibrosis was observed in 13.4% of the patients. The multivariable analysis resulted in a prediction model for grade⩾2 fibrosis in the boost area including three independent variables: patient age, breast volume receiving⩾55Gy (V55 CTV breast) and the maximum radiation dose in the breast (Dmax).
  
  
  
  A multivariable prediction model was developed including age, V55 CTV breast and Dmaxfor grade⩾2 fibrosis in the boost area after breast cancer RT using a 3D-CRT-SIB technique. This model can be used to estimate the risk of fibrosis and to optimize dose distributions aiming at reducing this risk.
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands. Electronic address: c.hammer@umcg.nl.
authors: C
authors: C
authors: Hammer
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: J H
authors: JH
authors: Maduro
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: E J
authors: EJ
authors: Bantema-Joppe
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: A
authors: A
authors: van der Schaaf
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: H P
authors: HP
authors: van der Laan
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: J A
authors: JA
authors: Langendijk
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: A P G
authors: AP
authors: Crijns
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D005355:Fibrosis; D006801:Humans; D016015:Logistic Models; D015412:Mastectomy, Segmental / Q000379:methods; D008875:Middle Aged; D009367:Neoplasm Staging; D017785:Photons / Q000627:therapeutic use*; D011446:Prospective Studies; D020266:Radiotherapy, Conformal / Q000379:methods*
keywords: Breast cancer; Fibrosis; Multivariable prediction model; NTCP; Radiotherapy