title: Oral contraceptive use and breast cancer: a prospective study of young women.
abstract: BACKGROUND
  Previous studies convincingly showed an increase in risk of breast cancer associated with current or recent use of oral contraceptives from the 1960s to 1980s. The relation of contemporary oral contraceptive formulations to breast cancer risk is less clear.
  
  
  METHODS
  We assessed lifetime oral contraceptive use and the specific formulations used among 116,608 female nurses ages 25 to 42 years at enrollment in 1989, and subsequently updated this information every 2 years. We related this information to risk of breast cancer up to June 1, 2001.
  
  
  RESULTS
  During 1,246,967 person-years of follow-up, 1,344 cases of invasive breast cancer were diagnosed. Past use of any oral contraceptive was not related to breast cancer risk [multivariate relative risk (RR), 1.12; 95% confidence interval 0.95-1.33]. Current use of any oral contraceptive was related to a marginally significant higher risk (multivariate RR, 1.33; 95% CI, 1.03-1.73). One specific formulation substantially accounted for the excess risk: the RR for current use of triphasic preparations with levonorgestrel as the progestin was 3.05 (95% CI, 2.00-4.66; P < 0.0001).
  
  
  CONCLUSIONS
  Current use of oral contraceptives carries an excess risk of breast cancer. Levonorgestrel used in triphasic preparations may account for much of this elevation in risk.
  
  
  CONCLUSIONS
  Different oral contraceptive formulations might convey different risks of breast cancer; ongoing monitoring of these associations is necessary as oral contraceptive formulations change.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA. dhunter@hsph.harvard.edu
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.forename: Susan
authors.initials: S
authors.lastname: Malspeis
authors.forename: Donna
authors.initials: D
authors.lastname: Spiegelman
authors.forename: Wendy
authors.initials: W
authors.lastname: Chen
authors.forename: Meir J
authors.initials: MJ
authors.lastname: Stampfer
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
chemical_list: D003278:Contraceptives, Oral, Hormonal
references.citation: Cancer Causes Control. 2003 Mar;14(2):151-60
references.pmid: 12749720
references.citation: Cancer. 1990 Dec 1;66(11):2253-63
references.pmid: 2147122
references.citation: Contraception. 1997 Dec;56(6):373-8
references.pmid: 9494771
references.citation: Am J Epidemiol. 2007 May 15;165(10):1187-98
references.pmid: 17337757
references.citation: Am J Epidemiol. 2000 Nov 15;152(10):950-64
references.pmid: 11092437
references.citation: J Natl Cancer Inst. 1989 Sep 6;81(17):1313-21
references.pmid: 2769784
references.citation: Contraception. 1985 Jun;31(6):557-70
references.pmid: 3899503
references.citation: Breast J. 2008 Sep-Oct;14(5):450-5
references.pmid: 18657146
references.citation: Am J Obstet Gynecol. 1994 May;170(5 Pt 2):1508-13
references.pmid: 8178899
references.citation: Contraception. 1996 Sep;54(3 Suppl):1S-106S
references.pmid: 8899264
references.citation: N Engl J Med. 2002 Jun 27;346(26):2025-32
references.pmid: 12087137
references.citation: Epidemiology. 1993 May;4(3):218-28
references.pmid: 8512986
references.citation: Br J Cancer. 2003 Jan 13;88(1):50-7
references.pmid: 12556959
references.citation: Steroids. 2000 Oct-Nov;65(10-11):659-64
references.pmid: 11108873
references.citation: Contraception. 1987 Aug;36(2):181-92
references.pmid: 3427965
references.citation: Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1375-81
references.pmid: 12433714
references.citation: Lancet. 1996 Jun 22;347(9017):1713-27
references.pmid: 8656904
references.citation: J Natl Cancer Inst. 2002 Apr 17;94(8):606-16
references.pmid: 11959894
references.citation: Am J Obstet Gynecol. 1997 Jan;176(1 Pt 1):123-8
references.pmid: 9024102
references.citation: J Natl Cancer Inst Monogr. 1994;(16):139-47
references.pmid: 7999456
references.citation: Am J Epidemiol. 2009 Feb 15;169(4):473-9
references.pmid: 19074777
references.citation: N Engl J Med. 2002 Jun 27;346(26):2078-9
references.pmid: 12087145
references.citation: Cancer Epidemiol Biomarkers Prev. 2007 Sep;16(9):1822-7
references.pmid: 17855700
references.citation: Hum Pathol. 1989 Dec;20(12):1139-44
references.pmid: 2591943
references.citation: Breast Cancer Res Treat. 2001 Jan;65(2):163-9
references.pmid: 11261832
references.citation: JAMA. 2000 Jan 26;283(4):485-91
references.pmid: 10659874