title: Obesity and the outcome of young breast cancer patients in the UK: the POSH study.
abstract: BACKGROUND
  Obese breast cancer patients have a poorer prognosis than non-obese patients. We examined data from a large prospective cohort study to explore the associations of obesity with tumour pathology, treatment and outcome in young British breast cancer patients receiving modern oncological treatments.
  
  
  METHODS
  A total of 2956 patients aged ≤40 at breast cancer diagnosis were recruited from 126 UK hospitals from 2001 to 2007. Height and weight were measured at registration. Tumour pathology and treatment details were collected. Follow-up data were collected at 6, 12 months, and annually.
  
  
  RESULTS
  A total of 2843 eligible patients (96.2%) had a body mass index (BMI) recorded: 1526 (53.7%) were under/healthy-weight (U/H, BMI <25 kg/m(2)), 784 (27.6%) were overweight (ov, BMI ≥25 to <30), and 533 (18.7%) were obese (ob, BMI ≥30). The median tumour size was significantly higher in obese and overweight patients than U/H patients (Ob 26 mm versus U/H 20 mm, P < 0.001; Ov 24 mm versus U/H 20 mm, P < 0.001). Obese and overweight patients had significantly more grade 3 tumours (63.9% versus 59.0%, P = 0.048; Ov 63.6% versus U/H 59.0% P = 0.034) and node-positive tumours (Ob 54.6% versus U/H 49.0%, P = 0.027; Ov 54.2% versus U/H 49%, P = 0.019) than U/H patients. Obese patients had more ER/PR/HER2-negative tumours than healthy-weight patients (25.0% versus 18.3%, P = 0.001). Eight-year overall survival (OS) and distant disease-free interval (DDFI) were significantly lower in obese patients than healthy-weight patients [OS: hazard ratio (HR) 1.65, P < 0.001; DDFI: HR 1.44, P < 0.001]. Multivariable analyses adjusting for tumour grade, size, nodal, and HER2 status indicated that obesity was a significant independent predictor of OS and DDFI in patients with ER-positive disease.
  
  
  CONCLUSIONS
  Young obese breast cancer patients present with adverse tumour characteristics. Despite adjustment for this, obesity still independently predicts DDFI and OS.
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton. Electronic address: e.copson@soton.ac.uk.
authors.forename: E R
authors.initials: ER
authors.lastname: Copson
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: R I
authors.initials: RI
authors.lastname: Cutress
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: T
authors.initials: T
authors.lastname: Maishman
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: B K
authors.initials: BK
authors.lastname: Eccles
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: S
authors.initials: S
authors.lastname: Gerty
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: L
authors.initials: L
authors.lastname: Stanton
authors.affiliation: Centre for Statistics in Medicine, Wolfson College Annexe, Oxford.
authors.forename: D G
authors.initials: DG
authors.lastname: Altman
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: L
authors.initials: L
authors.lastname: Durcan
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: C
authors.initials: C
authors.lastname: Wong
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: P D
authors.initials: PD
authors.lastname: Simmonds
authors.affiliation: Tumour Biology Department, Institute of Cancer, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London, UK.
authors.forename: L
authors.initials: L
authors.lastname: Jones
authors.affiliation: Cancer Sciences Academic Unit and University of Southampton Clinical Trials Unit, Faculty of Medicine, University of Southampton and University Hospital Southampton Foundation Trust, Tremona Road, Southampton.
authors.forename: D M
authors.initials: DM
authors.lastname: Eccles
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D009765:Obesity / Q000473:pathology*; D011446:Prospective Studies; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011982:Receptors, Prostaglandin / Q000378:metabolism; D016896:Treatment Outcome; D006113:United Kingdom; D055815:Young Adult
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011982:Receptors, Prostaglandin; C508053:ERBB2 protein, human
keywords: breast cancer; obesity; prognosis