title: The effect of body mass index and oestrogen receptor level on survival of breast cancer patients.
abstract: BACKGROUND
  Epidemiological studies have demonstrated that obesity and low oestrogen receptor level adversely affect survival from breast cancer. Few studies have examined the joint effects of these variables.
  
  
  METHODS
  A cohort study was conducted in which 1169 breast cancer patients from the Northern Alberta Breast Cancer Registry were followed for an average of 4.4 years. A number of variables related to breast cancer incidence and prognosis were studied. Body mass index (BMI) was used as a proxy measure of obesity.
  
  
  RESULTS
  A Cox regression analysis resulted in a final model with terms for size of tumour, number of positive axillary nodes, oestrogen receptor level, BMI, and age at diagnosis, plus an interaction term for node status and BMI. Having relatively less oestrogen receptor increased the hazard ratio by 1.8 (95% CI: 1.4-2.3); for woman with no positive nodes, being in the highest quartile of BMI increased the hazard ratio by 2.5 (95% CI: 1.2-5.2) compared to the lowest quartile.
  
  
  CONCLUSIONS
  BMI and oestrogen receptor level independently influence survival from breast cancer, but BMI affects survival only in patients with no positive axillary nodes.
authors.affiliation: Department of Psychiatry, Mackenzie Health Sciences Centre, University of Alberta, Edmonton, Canada.
authors.forename: S C
authors.initials: SC
authors.lastname: Newman
authors.forename: A W
authors.initials: AW
authors.lastname: Lees
authors.forename: H J
authors.initials: HJ
authors.lastname: Jenkins
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000401:mortality* / Q000628:therapy; D015331:Cohort Studies; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016013:Likelihood Functions; D008875:Middle Aged; D009367:Neoplasm Staging; D009765:Obesity / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011960:Receptors, Estrogen / Q000032:analysis*; D012042:Registries; D012306:Risk; D016019:Survival Analysis
chemical_list: D011960:Receptors, Estrogen