Prospective Study of Smoking and the Risk of Breast Cancer

TLDR: It is suggested that smoking and breast cancer are not materially related and there is no dose-response relationship across categories of current smoking.

Abstract: In 1976, 117,557 women in the United States aged 30-55 years and without a history of cancer provided detailed information on current smoking habits By 1986, 1,788 cases of breast cancer had been documented during 1,133,682 person-years There was no association between current smoking and risk of breast cancer (multivariate-adjusted relative risk for smokers of greater than or equal to 25 cigarettes/day compared to nonsmokers: 102, 95% confidence interval, 096-122) Past smoking also was unrelated to breast cancer risk (relative risk, 108; 95% confidence interval, 096-120) The results did not differ by menopausal status Tumor size and the presence of nodal metastases were unrelated to smoking Smoking was weakly associated with estrogen receptor-positive tumors (relative risk for smokers of greater than or equal to 25 cigarettes/day compared with never smokers, 138; 95% confidence interval, 104-184), but there was no dose-response relationship across categories of current smoking These results suggest that smoking and breast cancer are not materially related