title: Survival of patients with bilateral versus unilateral breast cancer and impact of guideline adherent adjuvant treatment: a multi-centre cohort study of 5292 patients.
abstract: This retrospective multi-centre study is focussed on recurrence free and overall survival of bilateral breast cancer (BBC) versus unilateral breast cancer (UBC). The impact of BBC on survival is stratified to guideline adherence, according to the German national S3-guideline. Another aim of the study is to identify the influence of various guideline violations in adjuvant treatment on survival of BBC patients. 229 (4.3%) patients had BBC and 5063 (95.7%) had UBC. There is a significant association between BBC/UBC and recurrence free (RFS: p < 0.001) and overall survival (OAS: p = 0.003). Only 15.7% of patients with BBC are treated 100% guideline adherent (index- + contralateral tumour). 31.0% (30.5%) were guideline adherent with respect to the index (contralateral) tumour. The outcome decreases significantly with the number of guideline violations. There was no significant difference in RFS and OAS between BBC and UBC after adjusting for tumour size, nodal status, grading and if guideline adherent treatment was applied.
  
  
  CONCLUSIONS
  1. Patients with BBC have primarily a worse prognosis in terms of RFS and OAS than patients with primarily UBC. 2. There is a strong association between guideline adherence and RFS/OAS of patients with BBC or UBC. The outcome decreases with the number of guideline violations. 3. If guideline adherent treatment was applied (for both tumours in case of BBC) there was no significant difference in RFS and OAS between BBC and UBC after adjusting for tumour size, nodal status, grading.
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital Ulm, Prittwitzstrasse 43, 89075 Ulm, Germany. lukas.schwentner@uniklinik-ulm.de
authors.forename: Lukas
authors.initials: L
authors.lastname: Schwentner
authors.forename: Regine
authors.initials: R
authors.lastname: Wolters
authors.forename: Manfred
authors.initials: M
authors.lastname: Wischnewsky
authors.forename: Rolf
authors.initials: R
authors.lastname: Kreienberg
authors.forename: Achim
authors.initials: A
authors.lastname: Wöckel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality* / Q000628:therapy*; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000401:mortality* / Q000628:therapy*; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome