title: Adjuvant radiotherapy after breast conserving surgery - a comparative effectiveness research study.
abstract: OBJECTIVE
  The purpose of this retrospective outcome study was to validate the effectiveness of postoperative radiotherapy in breast conserving therapy (BCT) and to evaluate possible causes for omission of radiotherapy after breast conserving surgery (BCS) in a non-trial population.
  
  
  METHODS
  Data were provided by the population-based Munich Cancer Registry. The study included epidemiological data of 30.811 patients diagnosed with breast cancer from 1998 to 2012. The effect of omitting radiotherapy was analysed using Kaplan-Meier-estimates and Cox proportional hazard regression. Variables predicting omission of radiotherapy were analysed using multivariate logistic regression.
  
  
  RESULTS
  Use of postoperative radiotherapy after BCS was associated with significant improvements in local control and survival. 10-year loco-regional recurrence-free-survival was 90.8% with postoperative radiotherapy vs. 77.6% with surgery alone (p<0.001). 10-year overall survival rates were 55.2% with surgery alone vs. 82.2% following postoperative radiotherapy (p<0.001). Variables predicting omission of postoperative radiotherapy included advanced age (women ⩾80 years; OR: 0.082; 95% CI: 0.071-0.094, p<0.001).
  
  
  CONCLUSIONS
  This study shows a decrease in local control and a survival disadvantage if postoperative radiotherapy after breast conserving surgery is omitted in an unselected cohort of primary breast cancer patients. Due to its epidemiological nature, it cannot answer the question in whom postoperative radiotherapy can be safely omitted.
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany. Electronic address: stefanie.corradini@med.uni-muenchen.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Corradini
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Niyazi
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Olivier M
authors.initials: OM
authors.lastname: Niemoeller
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Minglun
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Roeder
authors.affiliation: Munich Cancer Registry (MCR) of the Munich Cancer Centre (MCC) at the Department of Medical Informatics, Biometry and Epidemiology (IBE), University of Munich, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Eckel
authors.affiliation: Munich Cancer Registry (MCR) of the Munich Cancer Centre (MCC) at the Department of Medical Informatics, Biometry and Epidemiology (IBE), University of Munich, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schubert-Fritschle
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Heike R
authors.initials: HR
authors.lastname: Scheithauer
authors.affiliation: Breast Center, Department of Obstetrics and Gynecology, University of Munich, Germany; Comprehensive Cancer Center (CCC-LMU), University of Munich, Germany.
authors.forename: Nadia
authors.initials: N
authors.lastname: Harbeck
authors.affiliation: Munich Cancer Registry (MCR) of the Munich Cancer Centre (MCC) at the Department of Medical Informatics, Biometry and Epidemiology (IBE), University of Munich, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Engel
authors.affiliation: Department of Radiation Oncology, University of Munich, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D057186:Comparative Effectiveness Research; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental / Q000379:methods / Q000401:mortality; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy; D011182:Postoperative Care / Q000379:methods / Q000401:mortality; D018714:Radiotherapy, Adjuvant / Q000379:methods / Q000401:mortality; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Breast cancer; Breast conserving surgery; Comparative effectiveness research; Outcome; Radiotherapy