title: The impact of adjuvant radiotherapy on the survival of primary breast cancer patients: a retrospective multicenter cohort study of 8935 subjects.
abstract: BACKGROUND
  Radiotherapy (RT) is proven to be an important backbone for adjuvant therapy in randomized, controlled trials, but it is unclear if these effects are provable in a daily routine cohort of breast cancer patients. This study sought to answer the following questions in a daily routine cohort of breast cancer patients: 1. Does guideline-adherent RT improve primary breast cancer patient survival? 2. Is breast-conserving surgery (BCS) followed by RT equal to a mastectomy (MA) with regard to outcome parameters? 3. Does adjuvant RT compensate for an incomplete tumor resection (R1)?
  
  
  METHODS
  In this retrospective, multicenter cohort study, we investigated data from 8935 primary breast cancer patients recruited from 17 participating certified breast cancer centers in Germany between 1992 and 2008. Guideline adherence based on internationally validated guidelines.
  
  
  RESULTS
  The patients who received guideline-adherent RT for primary breast cancer were associated with significantly improved survival parameters [recurrence-free survival (RFS): P < 0.001; overall survival (OS): P < 0.001] compared with patients who did not receive guideline-adherent adjuvant RT. Furthermore, the results demonstrated that there were no significant differences in RFS and OS between BCS followed by RT and MA [RFS: P = 0.293; OS: P = 0.104]. Adjuvant RT did not improve the outcome of patients receiving nonguideline-adherent incomplete tumor resection via BCS (R1); these patients showed a significantly impaired RFS [P < 0.001] and OS [P < 0.001] compared with patients who underwent guideline-adherent complete tumor resection via BCS (R0). In addition, non-guideline-adherent RT after MA (overtherapy) did not significantly influence survival [RFS: P = 0.838; OS: P = 0.613].
  
  
  CONCLUSIONS
  Our study confirms the importance of guideline-adherent adjuvant RT. It shows highly significant associations between RFS or OS and guideline adherent RT. Nevertheless, inadequate (R1-) surgical resection in a daily routine cohort of patients increases the risk of local recurrence and appears not to be compensated by the following RT.
authors: Department of Gynecology and Obstetrics, University Ulm, Ulm.
authors: A
authors: A
authors: Wöckel
authors: Department of Mathematics and Computer Science, University Bremen, Bremen.
authors: R
authors: R
authors: Wolters
authors: Department of Radiotherapy and Radiooncology, University Ulm, Ulm, Germany.
authors: T
authors: T
authors: Wiegel
authors: Department of Mathematics and Computer Science, University Bremen, Bremen.
authors: I
authors: I
authors: Novopashenny
authors: Department of Gynecology and Obstetrics, University Ulm, Ulm.
authors: W
authors: W
authors: Janni
authors: Department of Gynecology and Obstetrics, University Ulm, Ulm.
authors: R
authors: R
authors: Kreienberg
authors: Department of Mathematics and Computer Science, University Bremen, Bremen.
authors: M
authors: M
authors: Wischnewsky
authors: Department of Gynecology and Obstetrics, University Ulm, Ulm. Electronic address: lukas.schwentner@yahoo.de.
authors: L
authors: L
authors: Schwentner
mesh_terms: D001943:Breast Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D015331:Cohort Studies; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D015412:Mastectomy, Segmental; D009364:Neoplasm Recurrence, Local / Q000401:mortality; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
keywords: breast cancer; cohort; guideline adherence; radiotherapy; survival