title: The role of boost and hypofractionation as adjuvant radiotherapy in patients with DCIS: a meta-analysis of observational studies.
abstract: OBJECTIVE
  The purpose of this meta-analysis is to summarize the current evidence on the role of boost and the efficacy of hypofractionated radiotherapy in patients with ductal cancer in situ (DCIS) after surgery and grade the quality of evidence.
  
  
  METHODS
  A comprehensive systematic electronic search through MEDLINE and the Cochrane Library as well as through the major international congresses' proceedings was conducted. Studies were considered eligible if they investigated the efficacy of hypofractionated vs. standard radiotherapy or the efficacy of boost vs. no boost in patients with DCIS. The outcome of interest was the number of local recurrences. Pooled estimates were calculated by using standard meta-analytic procedures.
  
  
  RESULTS
  Thirteen trials were considered eligible and were further analyzed. No difference in the risk of local recurrence was observed between the patients that received boost vs. no boost in the general cohort (12 studies, 6943 patients; Odds Ratio (OR): 0.91, 95% confidence interval (CI): 0.77-1.08, very low level of evidence). However, we found a reduced risk for local recurrence when boost was administered in patients with positive margins compared to no boost (6 studies, 811 patients; OR: 0.56, 95% CI: 0.36-0.87, very low level of evidence). No difference in local recurrence rate between patients who received hypofractionated versus standard radiotherapy was observed (4 studies, 2534 patients; OR: 0.78, 95% CI: 0.58-1.03, low level of evidence).
  
  
  CONCLUSIONS
  Hypofractionated radiotherapy seems to be a safe option in patients with DCIS after breast-conserving surgery while the addition of boost reduces the risk for local recurrence in the presence of positive margins. However, the level of evidence for these observations ranges between very low and low and the results of the ongoing randomized trials are necessary to confirm the results with higher level of evidence.
authors.affiliation: Center for Clinical Research, Västmanlands County Hospital, Västerås, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Nilsson
authors.affiliation: Centre for Clinical Research Sörmland, Uppsala University, Eskilstuna, Sweden. Electronic address: valachis@hotmail.com.
authors.forename: Antonis
authors.initials: A
authors.lastname: Valachis
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy*; D064887:Observational Studies as Topic; D018714:Radiotherapy, Adjuvant / Q000379:methods; D012307:Risk Factors
keywords: Boost; DCIS; Hypofractionation; Meta-analysis; Radiotherapy