title: Whole-breast irradiation: a subgroup analysis of criteria to stratify for prone position treatment.
abstract: To select among breast cancer patients and according to breast volume size those who may benefit from 3D conformal radiotherapy after conservative surgery applied with prone-position technique. Thirty-eight patients with early-stage breast cancer were grouped according to the target volume (TV) measured in the supine position: small (≤400 mL), medium (400-700 mL), and large (≥700 ml). An ad-hoc designed and built device was used for prone set-up to displace the contralateral breast away from the tangential field borders. All patients underwent treatment planning computed tomography in both the supine and prone positions. Dosimetric data to explore dose distribution and volume of normal tissue irradiated were calculated for each patient in both positions. Homogeneity index, hot spot areas, the maximum dose, and the lung constraints were significantly reduced in the prone position (p < 0.05). The maximum heart distance and the V(5Gy) did not vary consistently in the 2 positions (p = 0.06 and p = 0.7, respectively). The number of necessary monitor units was significantly higher in the supine position (312 vs. 232, p < 0.0001). The subgroups analysis pointed out the advantage in lung sparing in all TV groups (small, medium and large) for all the evaluated dosimetric constraints (central lung distance, maximum lung distance, and V(5Gy), p < 0.0001). In the small TV group, a dose reduction in nontarget areas of 22% in the prone position was detected (p = 0.056); in the medium and high TV groups, the difference was of about -10% (p = NS). The decrease in hot spot areas in nontarget tissues was 73%, 47%, and 80% for small, medium, and large TVs in the prone position, respectively. Although prone breast radiotherapy is normally proposed in patients with breasts of large dimensions, this study gives evidence of dosimetric benefit in all patient subgroups irrespective of breast volume size.
authors.affiliation: Radiation Oncology, Campus Bio-Medico University, Rome, Italy. s.ramella@unicampus.it
authors.forename: Sara
authors.initials: S
authors.lastname: Ramella
authors.forename: Lucio
authors.initials: L
authors.lastname: Trodella
authors.forename: Edy
authors.initials: E
authors.lastname: Ippolito
authors.forename: Michele
authors.initials: M
authors.lastname: Fiore
authors.forename: Francesco
authors.initials: F
authors.lastname: Cellini
authors.forename: Gerardina
authors.initials: G
authors.lastname: Stimato
authors.forename: Diego
authors.initials: D
authors.lastname: Gaudino
authors.forename: Carlo
authors.initials: C
authors.lastname: Greco
authors.forename: Sara
authors.initials: S
authors.lastname: Ramponi
authors.forename: Eugenio
authors.initials: E
authors.lastname: Cammilluzzi
authors.forename: Claudio
authors.initials: C
authors.lastname: Cesarini
authors.forename: Angelo
authors.initials: A
authors.lastname: Piermattei
authors.forename: Alfredo
authors.initials: A
authors.lastname: Cesario
authors.forename: Rolando Maria
authors.initials: RM
authors.lastname: D'Angelillo
mesh_terms: D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D009929:Organ Size; D018579:Patient Selection; D016684:Prone Position; D011879:Radiotherapy Dosage