CIGARETTE-SMOKING AND BREAST-CANCER

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 hospita l in Denmark. Subjects-3240 women aged 15-99 years referred for mammog raphy during 1 June 1989 to 1 November 1991. Main outcome measures-Smo king, parity, age, reason for referral, breast cancer. Results-In a mu ltiple logistic regression analysis adjusted for six variables a prono unced increased risk of breast cancer was found in women who had smoke d 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) year s for smokers and 67 (38-92) years for nonsmokers. The difference of e ight years between the median ages was significant (P<0.01). Conclusio n-Smoking may increase the risk of breast cancer after 30 years of smo king.