title: A multicenter matched case control study of breast cancer risk factors among women in Karachi, Pakistan.
abstract: BACKGROUND
  Breast cancer (BC), the most common female cancer in Pakistan, is associated with a very high mortality. However, the roles of individual risk factors for BC among Pakistani women are still controversial. To assess potential risk factors for BC, a matched case-control study was conducted in two tertiary care hospitals of Karachi, Pakistan.
  
  
  METHODS
  The study population included 297 pathologically confirmed incident cases of BC patients diagnosed between January 2009 and December 2010. 586 controls without any history of BC were matched on a hospital basis, within 5 years of patient ages.
  
  
  RESULTS
  Family history of BC (MOR=1.72; 95%CI: 1.10, 2.80 for first degree vs. none), single marital status (MOR=1.55; 95%CI: 1.10, 2.39 for single women vs. married women), older age at menopause (MOR=3.92; 95%CI: 2.52, 6.18 for menopausal women aged below 45 years, MOR=6.42; 95%CI: 3.47, 11.98 for menopausal women above 45 years of age compared with premenopausal women) conferred an increased risk of BC for women. Increasing parity decreased the risk of BC (MOR=0.90; 95%CI: 0.85, 0.97 for each live birth). Intake of Vitamin D supplements (MOR=0.30; 95%CI: 0.12, 0.81 for <3 years and MOR=0.27; 95%CI: 0.13, 0.56 for >3 years) was protective compared to non-users of Vitamin D.
  
  
  CONCLUSIONS
  This study confirmed only few of the recognized risk factors in Pakistani women. The protective effect of Vitamin D is important from public health perspective and needs to be further explored through a randomized controlled trial.
authors.affiliation: Epidemiology and Biostatistics, Department of Community Health Sciences, Aga Khan University Hospital, Pakistan. uzma.shamsi@aku.edu
authors.forename: Uzma
authors.initials: U
authors.lastname: Shamsi
authors.forename: Shaista
authors.initials: S
authors.lastname: Khan
authors.forename: Sheheryar
authors.initials: S
authors.lastname: Usman
authors.forename: Saleem
authors.initials: S
authors.lastname: Soomro
authors.forename: Iqbal
authors.initials: I
authors.lastname: Azam
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000235:genetics; D016022:Case-Control Studies; D016001:Confidence Intervals; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D017533:Marital Status; D008593:Menopause; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010154:Pakistan / Q000453:epidemiology; D010298:Parity; D012307:Risk Factors; D014807:Vitamin D / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D014807:Vitamin D