Smoking habit and benign breast disease.

The possible association between cigarette smoking and the risk of benign breast disease (BBD) was assessed in a case-control study conducted in Gdańsk, Poland, between 1990 and 1994. The study compared 160 women with newly diagnosed BBD admitted to the Gdańsk Cancer Outpatients Clinic and 160 controls, women from outpatients clinics at the Medical University of Gdańsk. There was no convincing evidence of an association, either positive or negative, between various indicators of smoking habit (smoking status, number of cigarettes smoked per day, duration of smoking) and the risk of BBD. Slightly lower relative risks (RRs) of BBD in ex-smokers of 10 or more cigarettes per day (RR = 0.9; 95% confidence interval, CI: 0.4-2.2), and with duration of smoking > or = 20 years (RR = 0.8; 95% CI: 0.1-3.4), were also observed in current smokers (RR = 0.8; 95% CI: 0.4-1.5), and (RR = 0.8; 95% CI: 0.1-3.4), but these findings were not statistically significant.