title: Tumor bed volumetric changes during breast irradiation for the patients with breast cancer.
abstract: OBJECTIVE
  The aim of this study was to evaluate changes in breast tumor bed volume during whole breast irradiation (WBI).
  
  
  METHODS
  From September 2011 to November 2012, thirty patients who underwent breast-conserving surgery (BCS) followed by WBI using computed tomography (CT) simulation were enrolled. Simulation CT scans were performed before WBI (CT1) and five weeks after the breast irradiation (CT2). The tumor bed was contoured based on surgical clips, seroma, and postoperative change. We retrospectively analyzed the factors associated with tumor bed volumetric change.
  
  
  RESULTS
  The median tumor bed volume on CT1 and CT2 was 29.72 and 28.6 mL, respectively. The tumor bed volume increased in 9 of 30 patients (30%) and decreased in 21 of 30 patients (70%). The median percent change in tumor bed volume between initial and boost CT was -5%. Seroma status (p = 0.010) was a significant factor in tumor bed volume reduction of 5% or greater. However, patient age, body mass index, palpability, T stage, axillary lymph node dissection, and tumor location were not significant factors for tumor bed volumetric change.
  
  
  CONCLUSIONS
  In this study, volumetric change of tumor bed cavity was frequent. Patients with seroma after BCS had a significant volume reduction of 5% or greater in tumor bed during breast irradiation. Thus, resimulation using CT is indicated for exquisite boost treatment in breast cancer patients with seroma after surgery.
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Mi Joo
authors: MJ
authors: Chung
authors: Department of Surgery, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Young Jin
authors: YJ
authors: Suh
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Hyo Chun
authors: HC
authors: Lee
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Dae Gyu
authors: DG
authors: Kang
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Eun Joong
authors: EJ
authors: Kim
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Sung Hwan
authors: SH
authors: Kim
authors: Department of Radiation Oncology, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Jong Hoon
authors: JH
authors: Lee
keywords: Breast neoplasms; Lumpectomy cavity; Radiation