Abstract: ObjectiveTo study the relationship between smoking and the incidence of female breast cancer and to provide basis for prevention of the disease.MethodsWith hospital-based 1:1 matched case-control design,a questionnaire survey was conducted in 163 female breast cancer cases and 163 females with nonturmorous,non-reproductive and endocrine system diseases selected from Fengtian Hospital,Shenzhou Hospital and the Fifth People's Hospital of Shenyang city.ResultsSignificantly higher rates of active smoking(9.20%),passive smoking(34.36%),heavy active smoking(5.52%),high exposure of passive smoking(27.61%),long years of passive smoking(25.15%),smoking during pregnancy(23.31%),and first smoking at the age of <18 years(17.79%) were observed in the cases compared to those in the control group(3.68%,13.49%,1.23%,6.13%,9.20%,5.52%,and 4.29%; P<0.05 for all).Multiple-factor conditional logistic regression analyses indicated that the risk factors of breast cancer included family history of tumor,severe life event,obesity,heavy active smoking,high exposure of passive smoking,and smoking during pregnancy.ConclusionHeavy active and passive smoking and smoking during pregnancy may increase the risk of breast cancer in women.