title: The predictive impact of body mass index on the efficacy of extended adjuvant endocrine treatment with anastrozole in postmenopausal patients with breast cancer: an analysis of the randomised ABCSG-6a trial.
abstract: BACKGROUND
  We investigated whether body mass index (BMI) can be used as a predictive parameter indicating patients who benefit from extended aromatase inhibitor (AI) treatment.
  
  
  METHODS
  The ABCSG-6a trial re-randomised event-free postmenopausal hormone receptor-positive patients from the ABCSG-6 trial to receive either 3 additional years of endocrine therapy using anastrozole vs nil. In this retrospective analysis, we investigated the prognostic and predictive impact of BMI on disease outcome and safety.
  
  
  RESULTS
  In all, 634 patients (177 normal weight, 307 overweight, and 150 obese) patients were included in this analysis. Normal weight patients with additional 3 years of anastrozole halved their risk of disease recurrence (disease-free survival (DFS) HR 0.48; P=0.02) and death (HR 0.45; P=0.06) and had only a fifth of the risk of distant metastases (HR 0.22; P=0.05) compared with normal weight patients without any further treatment. In contrast, overweight+obese patients derived no benefit from additional 3 years of anastrozole (DFS HR 0.93; P=0.68; distant recurrence-free survival HR 0.91; P=0.78; and OS HR 0.9; P=0.68). The possible predictive impact of BMI on extended endocrine treatment could be strengthened by a Cox regression interaction model between BMI and treatment (P=0.07).
  
  
  CONCLUSIONS
  Body mass index may be used to predict outcome benefit of extended AI treatment in patients with receptor-positive breast cancer.
authors.affiliation: Department of Surgery, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria. michael.gnant@meduniwien.ac.at
authors.forename: M
authors.initials: M
authors.lastname: Gnant
authors.forename: G
authors.initials: G
authors.lastname: Pfeiler
authors.forename: H
authors.initials: H
authors.lastname: Stöger
authors.forename: B
authors.initials: B
authors.lastname: Mlineritsch
authors.forename: F
authors.initials: F
authors.lastname: Fitzal
authors.forename: M
authors.initials: M
authors.lastname: Balic
authors.forename: W
authors.initials: W
authors.lastname: Kwasny
authors.forename: M
authors.initials: M
authors.lastname: Seifert
authors.forename: M
authors.initials: M
authors.lastname: Stierer
authors.forename: P
authors.initials: P
authors.lastname: Dubsky
authors.forename: R
authors.initials: R
authors.lastname: Greil
authors.forename: G
authors.initials: G
authors.lastname: Steger
authors.forename: H
authors.initials: H
authors.lastname: Samonigg
authors.forename: C
authors.initials: C
authors.lastname: Fesl
authors.forename: R
authors.initials: R
authors.lastname: Jakesz
mesh_terms: D000293:Adolescent; D000328:Adult; D000077384:Anastrozole; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000009:adverse effects; D047072:Aromatase Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000188:drug therapy*; D017024:Chemotherapy, Adjuvant; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008875:Middle Aged; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy*; D009570:Nitriles / Q000008:administration & dosage* / Q000009:adverse effects; D009765:Obesity / Q000503:physiopathology; D050177:Overweight / Q000503:physiopathology; D017698:Postmenopause; D012189:Retrospective Studies; D014230:Triazoles / Q000008:administration & dosage* / Q000009:adverse effects; D055815:Young Adult
chemical_list: D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole