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Cigarette smoking and breast cancer

BMJ 1995; 310 doi: https://doi.org/10.1136/bmj.310.6992.1431 (Published 03 June 1995) Cite this as: BMJ 1995;310:1431
  1. Kim Bennicke, senior registrara,
  2. Carsten Conrad, head physiciana,
  3. Svend Sabroe, associate professorb,
  4. Henrik Toft Sorensen, research associate professorc
  1. a Department of Radiology, Hjorring District Hospital, DK-9800, Hjorring, Denmark
  2. b Department of Epidemiology and Social Medicine, Aarhus University, DK-8000 Aarhus C, Denmark
  3. c Danish Epidemiology Science Centre, Steno Institute of Public Health, Aarhus University
  1. Correspondence to: Dr K Bennicke, Department of Radiology, Hobro District Hospital, DK-9500, Hobro, Denmark.
  • Accepted 11 April 1995

Abstract

Objective: To investigate cigarette smoking in relation to the risk of breast cancer.

Design: Interviews with women referred for mammography.

Setting: Hjorring District Hospital, a public, population based hospital in Denmark.

Subjects: 3240 women aged 15-92 years referred for mammography during 1 June 1989 to 1 November 1991.

Main outcome measures: Smoking, parity, age, reason for referral, breast cancer.

Results: In a multiple logistic regression analysis adjusted for six variables a pronounced increased risk of breast cancer was found in women who had smoked for over 20 years, and this was significant in women who had smoked for over 30 years (odds ratio 1.6, 95% confidence interval 1.1 to 2.3). The median age of women with breast cancer was 59 (range 31-81) years for smokers and 67 (38–92) years for nonsmokers. The difference of eight years between the median ages was significant (P<0.01).

Conclusion: Smoking may increase the risk of breast cancer after 30 years of smoking.

Key messages

  • Key messages

  • It has been suggested that smoking protects against breast cancer because of an antioestrogenic effect

  • This study shows, however, that women who have smoked for more than 30 years have an increased risk of developing breast cancer

  • Moreover, smokers with breast cancer were eight years younger than non-smokers with breast cancer

Footnotes

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