title: Body fat distribution and breast cancer risk: findings from the Nigerian breast cancer study.
abstract: OBJECTIVE
  The relationship between overall obesity and breast cancer risk has been well recognized, but the role of central obesity in breast cancer development is uncertain.
  
  
  METHODS
  Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 community controls were recruited into the Nigerian Breast Cancer Study at Ibadan, Nigeria. Logistic regressions were used to calculate multivariate odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, body mass index (BMI), and other known risk factors for breast cancer.
  
  
  RESULTS
  The OR for the highest quartile group of waist circumference relative to the lowest was 2.39 (95% CI, 1.59-3.60; P-trend < 0.001). Comparing women with waist/hip ratio (WHR) in the lowest quartile group, the OR for women in the highest quartile category was 2.15 (95% CI, 1.61-2.85; P-trend < 0.001). An inverse association was observed between hip circumference and breast cancer, with an OR of 0.36 for the highest quartile (95% CI, 0.24-0.55; P-trend < 0.001). The effects of these three measures existed in both pre- and postmenopausal women. Of note, we found a significant interaction between WHR and BMI (P-interaction = 0.016): the OR comparing the highest to the lowest WHR quartile was 2.81 (95% CI, 1.90-4.16) for women with BMI < 25 kg/m2 and 1.70 (95% CI, 1.11-2.61) for women with BMI ≥ 25 kg/m2.
  
  
  CONCLUSIONS
  These results suggest that central adiposity, measured by waist circumference and waist/hip ratio, was an important risk factor for breast cancer in Nigerian women, and the effect of central adiposity was strong in normal-weight women.
authors.affiliation: Department of Surgery College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Temidayo O
authors.initials: TO
authors.lastname: Ogundiran
authors.forename: Dezheng
authors.initials: D
authors.lastname: Huo
authors.forename: Adeniyi
authors.initials: A
authors.lastname: Adenipekun
authors.forename: Oladapo
authors.initials: O
authors.lastname: Campbell
authors.forename: Rasaaq
authors.initials: R
authors.lastname: Oyesegun
authors.forename: Effiong
authors.initials: E
authors.lastname: Akang
authors.forename: Clement
authors.initials: C
authors.lastname: Adebamowo
authors.forename: Olufunmilayo I
authors.initials: OI
authors.lastname: Olopade
mesh_terms: D000328:Adult; D050218:Body Fat Distribution; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D009765:Obesity / Q000150:complications; D012307:Risk Factors; D055105:Waist Circumference; D049629:Waist-Hip Ratio