title: Axillary Irradiation with High Tangent Fields for Clinically Node-Negative Breast Cancer: Can 3-D Conformal Radiotherapy with a Field-in-Field Technique Better Control the Axilla?
abstract: BACKGROUND
  The target volume for postoperative breast irradiation is the remaining breast tissue, and the axillary region is not an intentional target volume.
  
  
  METHODS
  Between 2001 and 2009, eligible women with pT1-2cN0/pN0(sn) breast cancer underwent breast-conserving therapy without axillary dissection. Treatment outcomes between 2 radiotherapy planning groups, high tangent fields with 2-dimensional (2-D) simulation-based planning and 3-dimensional (3-D) computed tomography-based planning with a field-in-field technique, were compared. The correlating factors for axillary failure were also calculated.
  
  
  RESULTS
  In total, 678 patients were eligible. As of May 2009, the median follow-up times for the 2-D (n = 346) and 3-D (n = 332) groups were 94 and 52 months, respectively. Patient characteristics were balanced, except for a younger population in the 2-D group and more lymphovascular invasion in the 3-D group. On multivariate analysis, 2-D planning was the only risk factor for axillary failure. In the 2-D and 3-D groups, the 5-year cumulative incidences of axillary failure were 8 (3.1%) and 1 (0.3%) (log-rank p = 0.009), respectively. The respective 5-year overall survival rates were 97.4 and 98.4% (p = 0.4).
  
  
  CONCLUSIONS
  High tangent irradiation with 3-D planning improved axillary control compared to that with 2-D planning, suggesting that optimizing axillary dose distribution may impact outcomes.
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kamakura, Japan ; Department of Radiation Oncology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Sanuki
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kamakura, Japan ; Department of Radiation Oncology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Atsuya
authors.initials: A
authors.lastname: Takeda
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Amemiya
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Ofuchi
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Ono
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Ogata
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamagami
authors.affiliation: Breast Cancer Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Hatayama
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kamakura, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Eriguchi
authors.affiliation: Department of Radiation Oncology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Etsuo
authors.initials: E
authors.lastname: Kunieda
keywords: Breast cancer; Conformal radiotherapy; Sentinel lymph node biopsy