title: Whole breast radiotherapy in the lateral decubitus position: a dosimetric and clinical solution to decrease the doses to the organs at risk (OAR).
abstract: OBJECTIVE
  To evaluate whole breast 3D-conformal radiotherapy (RT) delivered in the lateral decubitus position (isocentric lateral decubitus [ILD]) and to report the acute toxicity of a series of consecutive patients treated with ILD.
  
  
  METHODS
  From January to December 2010, 56 consecutive patients with large breasts and early-stage breast cancer treated by breast conserving surgery underwent 3D-conformal whole breast RT in the lateral decubitus position. A dose of 50 Gy in 25 fractions via two opposed isocentric beams was prescribed to whole breast, with or without a 16 Gy photon tumor bed boost. Dosimetry of all patients was reviewed, and the acute toxicity of treatment, evaluated weekly using the NCI CTC v3.0 scale, was analyzed.
  
  
  RESULTS
  Median age was 57 years (range: 33-71). 85% of patients had a breast circumference of at least 95 cm and 80% had at least a C cup size. Average breast volume was 991 cm(3) (range: 225-2791 cm(3)). Median dose to the breast was 50 Gy, while median dose to the tumor bed was 16 Gy. Grade 1, 2 and 3 dermatitis developed in 37.5%, 58.9% and 1.8% of patients, respectively. From a dosimetric point of view, doses to the ipsilateral lung were extremely low: average V(1Gy), V(2Gy) and V(5Gy) were 26.6%, 9.3% and 0.7%, respectively. Average mean lung dose was 0.96 Gy. For the 26 patients with left-sided tumors, heart doses were also extremely low: average V(1Gy), V(2Gy) and V(5Gy) were 58.8%, 14.2% and 0.7%, respectively. Average mean heart dose was 1.35 Gy.
  
  
  CONCLUSIONS
  Whole breast radiotherapy in the lateral decubitus position for patients with large breasts and early-stage breast cancer provides an excellent dosimetric profile, with low doses to the heart and ipsilateral lung. It is also very well tolerated, with a good acute toxicity profile.
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France. Electronic address: youlia.kirova@curie.net.
authors.forename: Youlia M
authors.initials: YM
authors.lastname: Kirova
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Tarek
authors.initials: T
authors.lastname: Hijal
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Francois
authors.initials: F
authors.lastname: Campana
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fournier-Bidoz
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Stilhart
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Dendale
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Fourquet
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk; D056888:Patient Positioning; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects
keywords: Breast cancer; Dosimetry; Lateral decubitus position; Radiotherapy