title: Cigarette smoking and risk of breast cancer in a New Zealand multi-ethnic case-control study.
abstract: BACKGROUND
  The association between breast cancer and tobacco smoke is currently unclear. The aim of this study was to assess the effect of smoking behaviours on the risk of breast cancer among three ethnic groups of New Zealand women.
  
  
  METHODS
  A population-based case-control study was conducted including breast cancer cases registered on the New Zealand Cancer Registry between 2005 and 2007. Controls were matched by ethnicity and 5-year age-group. Logistic regression was used to estimate the association between breast cancer and smoking at different time points across the lifecourse, for each ethnic group. Estimated odds ratios (OR) were adjusted for established risk factors.
  
  
  RESULTS
  The study comprised 1,799 cases (302 Māori, 70 Pacific, 1,427 non-Māori/non-Pacific) and 2,540 controls (746 Māori, 191 Pacific, 1,603 non-Māori/non-Pacific). There was no clear association between smoking and breast cancer for non-Māori/non-Pacific women, although non-Māori/non-Pacific ex-smokers had statistically significant increased risk of breast cancer when smoking duration was 20 years or more, and this remained significant in the fully adjusted model (OR 1.31, 95% CI 1.03 to 1.66). Māori showed more consistent increased risk of breast cancer with increasing duration among current smokers (<20 years OR 1.61, 95% CI 0.55 to 4.74; 20+ years OR 2.03, 95% CI 1.29 to 3.22). There was a clear pattern of shorter duration since smoking cessation being associated with increased likelihood of breast cancer, and this was apparent for all ethnic groups.
  
  
  CONCLUSIONS
  There was no clear pattern for cigarette smoking and breast cancer incidence in non-Māori/non-Pacific women, but increased risks were observed for Māori and Pacific women. These findings suggest that lowering the prevalence of smoking, especially among Māori and Pacific women, could be important for reducing breast cancer incidence.
authors: International Agency for Research on Cancer, Lyon, France. mckenzief@fellows.iarc.fr
authors: Fiona
authors: F
authors: McKenzie
authors: Lis
authors: L
authors: Ellison-Loschmann
authors: Mona
authors: M
authors: Jeffreys
authors: Ridvan
authors: R
authors: Firestone
authors: Neil
authors: N
authors: Pearce
authors: Isabelle
authors: I
authors: Romieu
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D009520:New Zealand / Q000453:epidemiology / Q000208:ethnology; D012306:Risk; D012907:Smoking
references: Cancer Causes Control. 2013 Jan;24(1):135-52
references: 23179663
references: Tob Control. 2011 Jan;20(1):e2
references: 21148114
references: Environ Health Perspect. 2005 Apr;113(4):412-7
references: 15811831
references: Am J Obstet Gynecol. 1990 Feb;162(2):502-14
references: 2178432
references: Int J Cancer. 2005 Mar 20;114(2):317-22
references: 15540214
references: Int J Cancer. 2002 Aug 20;100(6):723-8
references: 12209614
references: Lancet Oncol. 2009 Nov;10(11):1033-4
references: 19891056
references: Am J Obstet Gynecol. 2011 Jul;205(1):34.e1-13
references: 21514918
references: Eur J Cancer Prev. 1993 Nov;2 Suppl 3:85-100
references: 7905315
references: Lancet. 2002 Oct 5;360(9339):1044-9
references: 12383984
references: Cancer Res. 2002 Apr 1;62(7):1987-95
references: 11929815
references: BMJ. 2011 Mar 01;342:d1016
references: 21363864
references: Can J Appl Sport Sci. 1985 Sep;10(3):141-6
references: 4053261
references: Mayo Clin Proc. 2005 Nov;80(11):1423-8
references: 16295021
references: N Engl J Med. 1982 Oct 21;307(17):1062-5
references: 7121516
references: Breast Cancer Res Treat. 1982;2(1):5-73
references: 6216933
references: Cancer Causes Control. 2005 Oct;16(8):975-85
references: 16132806
references: Cancer Epidemiol Biomarkers Prev. 2004 Mar;13(3):398-404
references: 15006915
references: Cancer Causes Control. 2009 Dec;20(10):1837-44
references: 19533391
references: Climacteric. 2008;11(6):467-74
references: 18802815
references: Cancer Causes Control. 2000 Mar;11(3):211-21
references: 10782655
references: Breast Cancer Res Treat. 2006 Dec;100(3):293-9
references: 16773435
references: Arch Intern Med. 2011 Jan 24;171(2):125-33
references: 21263102
references: Cancer Epidemiol Biomarkers Prev. 2008 Jan;17(1):15-26
references: 18187392
references: Cancer Epidemiol Biomarkers Prev. 2002 Oct;11(10 Pt 1):953-71
references: 12376493
references: Am J Epidemiol. 2011 Aug 15;174(4):390-402
references: 21719745
references: Epidemiology. 2002 Mar;13(2):138-45
references: 11880753
references: Am J Epidemiol. 2007 Jul 1;166(1):55-61
references: 17426039
references: Br J Cancer. 2004 Aug 2;91(3):512-8
references: 15226777
references: J Natl Cancer Inst. 2004 Jan 7;96(1):29-37
references: 14709736
references: Cancer Epidemiol Biomarkers Prev. 2005 Jan;14(1):61-6
references: 15668477
references: Br J Cancer. 2002 Nov 18;87(11):1234-45
references: 12439712
references: Epidemiol Rev. 1993;15(1):145-56
references: 8405197
references: Environ Mol Mutagen. 2002;39(2-3):119-26
references: 11921179