title: Novel 10-fraction breast irradiation in prone and supine position: technical, dosimetric and clinical evaluation.
abstract: BACKGROUND
  The aim of this study was to evaluate retrospectively the planned dose distribution and acute toxicity of adjuvant hypofractionated whole breast radiotherapy (RT) delivered in the prone vs. supine position.
  
  
  METHODS
  Twenty-four patients were enrolled; 12 underwent adjuvant RT with a supine setup and 12 with a prone setup. We included patients according to breast volume (≥500 mL), disease stage (≤pT2/pN1), and clinical/biological features. Patients received a regimen of 35 Gy in 10 fractions for 2.5 weeks, and a concomitant boost of 3/4 Gy in 1 fraction/week. Target coverage was assessed by volume, V90, V95, V100, V103 and V105. Heart, LADCA and ipsilateral lung doses were evaluated according to volume, maximum dose, mean dose, V14, V10 and V5. We evaluated acute skin toxicity during RT, at the end of treatment, and after 1 month according to RTOG scales.
  
  
  RESULTS
  Radiobiological equivalence was warranted with satisfactory BED values: considering α/β = 4 for breast cancer, the 10-fraction schedule equaled 74 or 77 Gy depending on the boost dose (3 Gy vs. 4 Gy, respectively). Toxicity was low and similar for supine and prone treatments. Dose sparing was significant in the ipsilateral lung in the prone position (median Dmax: 28.7 Gy vs. 38.4 Gy; median Dmean: 0.8 Gy vs. 6.3 Gy; median V14: 0.6% vs. 13.5%; median V5: 0 vs. 19.3%, p&lt;0.001).
  
  
  CONCLUSIONS
  This novel 10-fraction schedule is feasible and well tolerated; the prone position allows better saving of OARs, with a statistically significant value for the ipsilateral lung.
authors.affiliation: Department of Radiation Oncology, IRCCS San Martino-IST, National Cancer Research Institute, Genoa - Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Guenzi
authors.forename: Davide
authors.initials: D
authors.lastname: Bosetti
authors.forename: Giorgio
authors.initials: G
authors.lastname: Lamanna
authors.forename: Guido
authors.initials: G
authors.lastname: Siffredi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bonzano
authors.forename: Marco
authors.initials: M
authors.lastname: Gusinu
authors.forename: Stefania
authors.initials: S
authors.lastname: Garelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Pupillo
authors.forename: Renzo
authors.initials: R
authors.lastname: Corvò
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000209:etiology; D005240:Feasibility Studies; D005260:Female; D005355:Fibrosis / Q000209:etiology; D006801:Humans; D008168:Lung / Q000473:pathology / Q000528:radiation effects*; D015412:Mastectomy, Segmental; D009367:Neoplasm Staging; D058958:Organs at Risk; D016684:Prone Position; D011874:Radiometry; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects* / Q000379:methods*; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology / Q000528:radiation effects; D016683:Supine Position; D016896:Treatment Outcome