title: Quantifying the impact of immediate reconstruction in postmastectomy radiation: a large, dose-volume histogram-based analysis.
abstract: OBJECTIVE
  To assess the impact of immediate breast reconstruction on postmastectomy radiation (PMRT) using dose-volume histogram (DVH) data.
  
  
  METHODS
  Two hundred forty-seven women underwent PMRT at our center, 196 with implant reconstruction and 51 without reconstruction. Patients with reconstruction were treated with tangential photons, and patients without reconstruction were treated with en-face electron fields and customized bolus. Twenty percent of patients received internal mammary node (IMN) treatment. The DVH data were compared between groups. Ipsilateral lung parameters included V20 (% volume receiving 20 Gy), V40 (% volume receiving 40 Gy), mean dose, and maximum dose. Heart parameters included V25 (% volume receiving 25 Gy), mean dose, and maximum dose. IMN coverage was assessed when applicable. Chest wall coverage was assessed in patients with reconstruction. Propensity-matched analysis adjusted for potential confounders of laterality and IMN treatment.
  
  
  RESULTS
  Reconstruction was associated with lower lung V20, mean dose, and maximum dose compared with no reconstruction (all P<.0001). These associations persisted on propensity-matched analysis (all P<.0001). Heart doses were similar between groups (P=NS). Ninety percent of patients with reconstruction had excellent chest wall coverage (D95 >98%). IMN coverage was superior in patients with reconstruction (D95 >92.0 vs 75.7%, P<.001). IMN treatment significantly increased lung and heart parameters in patients with reconstruction (all P<.05) but minimally affected those without reconstruction (all P>.05). Among IMN-treated patients, only lower lung V20 in those without reconstruction persisted (P=.022), and mean and maximum heart doses were higher than in patients without reconstruction (P=.006, P=.015, respectively).
  
  
  CONCLUSIONS
  Implant reconstruction does not compromise the technical quality of PMRT when the IMNs are untreated. Treatment technique, not reconstruction, is the primary determinant of target coverage and normal tissue doses.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
authors.forename: Nisha
authors.initials: N
authors.lastname: Ohri
authors.forename: Peter G
authors.initials: PG
authors.lastname: Cordeiro
authors.forename: Jennifer
authors.initials: J
authors.lastname: Keam
authors.forename: Ase
authors.initials: A
authors.lastname: Ballangrud
authors.forename: Weiji
authors.initials: W
authors.lastname: Shi
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Claire T
authors.initials: CT
authors.lastname: Nerbun
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Woch
authors.forename: Nicholas F
authors.initials: NF
authors.lastname: Stein
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Beryl
authors.initials: B
authors.lastname: McCormick
authors.forename: Simon N
authors.initials: SN
authors.lastname: Powell
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Ho
mesh_terms: D018427:Breast Implants; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000528:radiation effects; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000528:radiation effects; D015182:Lymphatic Irradiation / Q000379:methods; D016462:Mammaplasty / Q000379:methods* / Q000706:statistics & numerical data; D009929:Organ Size; D058958:Organs at Risk / Q000528:radiation effects*; D017785:Photons / Q000627:therapeutic use; D011184:Postoperative Period; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D035441:Thoracic Wall / Q000000981:diagnostic imaging / Q000528:radiation effects; D047368:Tumor Burden