title: Timing of radiotherapy following breast-conserving surgery: outcome of 1393 patients at a single institution.
abstract: BACKGROUND
  The role of postoperative radiotherapy in breast-conserving therapy is undisputed. However, optimal timing of adjuvant radiotherapy is an issue of ongoing debate. This retrospective clinical cohort study was performed to investigate the impact of a delay in surgery-radiotherapy intervals on local control and overall survival.
  
  
  METHODS
  Data from an unselected cohort of 1393 patients treated at a single institution over a 17-year period (1990-2006) were analyzed. Patients were assigned to two groups (CT+/CT-) according to chemotherapy status. A delay in the initiation of radiotherapy was defined as > 7 weeks (CT- group) and > 24 weeks (CT+ group).
  
  
  RESULTS
  The 10-year regional recurrence-free survival for the CT- and CT+ groups were 95.6 and 86.0 %, respectively. A significant increase in the median surgery-radiotherapy interval was observed over time (CT- patients: median of 5 weeks in 1990-1992 to a median of 6 weeks in 2005-2006; CT+ patients: median of 5 weeks in 1990-1992 to a median of 21 weeks in 2005-2006). There was no association between a delay in radiotherapy and an increased local recurrence rate (CT- group: p = 0.990 for intervals 0-6 weeks vs. ≥ 7 weeks; CT+ group: p = 0.644 for intervals 0-15 weeks vs. ≥ 24 weeks) or decreased overall survival (CT- group: p = 0.386 for intervals 0-6 weeks vs. ≥ 7 weeks; CT+ group: p = 0.305 for intervals 0-15 weeks vs. ≥ 24 weeks).
  
  
  CONCLUSIONS
  In the present cohort, a delay of radiotherapy was not associated with decreased local control or overall survival in the two groups (CT-/CT+). However, in the absence of randomized evidence, delays in the initiation of radiotherapy should be avoided.
authors.affiliation: Department of Radiation Oncology, University of Munich, Marchioninistr. 15, 81377, Munich, Germany, corradini.stefanie@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Corradini
authors.forename: O M
authors.initials: OM
authors.lastname: Niemoeller
authors.forename: M
authors.initials: M
authors.lastname: Niyazi
authors.forename: F
authors.initials: F
authors.lastname: Manapov
authors.forename: M
authors.initials: M
authors.lastname: Haerting
authors.forename: N
authors.initials: N
authors.lastname: Harbeck
authors.forename: C
authors.initials: C
authors.lastname: Belka
authors.forename: S
authors.initials: S
authors.lastname: Kahlert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality* / Q000628:therapy*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015412:Mastectomy, Segmental / Q000401:mortality*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality* / Q000517:prevention & control*; D015995:Prevalence; D018714:Radiotherapy, Adjuvant / Q000401:mortality*; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D014850:Waiting Lists