title: Radiotherapy boost dose-escalation for invasive breast cancer after breast-conserving surgery: 2093 patients treated with a prospective margin-directed policy.
abstract: OBJECTIVE
  To investigate the outcome of invasive early breast cancer patients that underwent breast-conserving surgery and adjuvant radiotherapy (RT), treated with a prospective margin-directed institutional policy for RT boost dose, based on final margins status (FMS).
  
  
  METHODS
  A total of 2093 patients were treated between 2000 and 2008. 10 Gy boost was prescribed in case of FMS>5mm; 16 Gy boost with FMS between 2 and 5mm; 20 Gy boost in case of FMS<2mm or positive.
  
  
  RESULTS
  After a median follow up of 5.2 years, we recorded 41 local relapse (LR, 2%). Concerning LR free survival, age at diagnosis, nuclear grade, hormonal status, T-stage, adjuvant hormonal therapy and adjuvant chemotherapy emerged as significant parameters (p-values from log rank test <0.05). FMS, that directed the RT boost dose, did not have significant impact on LRFS (p=0.46). LR rates were 2.3% for FMS<2mm, 2.6% for 2-5mm FMS and 1.8% for FMS>5mm. At multivariate analysis, higher nuclear grade (p=0.045), triple negative subtype (p=0.036) and higher T-stage (p=0.02) resulted as the independent predictors of LR occurrence.
  
  
  CONCLUSIONS
  Our experience showed that a margin-directed policy of RT boost dose-escalation seems to reduce the negative impact of FMS on LR, but it is not able to overcome the unfavorable effect of higher nuclear grade, higher T stage and triple negative subtype.
authors.affiliation: Radiotherapy Unit, University of Florence, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Livi
authors.forename: Icro
authors.initials: I
authors.lastname: Meattini
authors.forename: Davide
authors.initials: D
authors.lastname: Franceschini
authors.forename: Calogero
authors.initials: C
authors.lastname: Saieva
authors.forename: Fiammetta
authors.initials: F
authors.lastname: Meacci
authors.forename: Livia
authors.initials: L
authors.lastname: Marrazzo
authors.forename: Elena
authors.initials: E
authors.lastname: Gerlain
authors.forename: Isacco
authors.initials: I
authors.lastname: Desideri
authors.forename: Vieri
authors.initials: V
authors.lastname: Scotti
authors.forename: Jacopo
authors.initials: J
authors.lastname: Nori
authors.forename: Luis Jose
authors.initials: LJ
authors.lastname: Sanchez
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Orzalesi
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Bonomo
authors.forename: Daniela
authors.initials: D
authors.lastname: Greto
authors.forename: Simonetta
authors.initials: S
authors.lastname: Bianchi
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Biti
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D015331:Cohort Studies; D016208:Databases, Factual; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental / Q000379:methods; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018714:Radiotherapy, Adjuvant; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: Breast-conserving surgery; Dose escalation; Invasive breast cancer; Radiotherapy boost; Tumor margins