Smoking Tied to Modest Increase in Breast Cancer Risk

February 9, 2011

Active smoking has a modest effect on the risk of developing breast cancer, according to a study published in the Jan. 24 issue of the Archives of Internal Medicince.

TUESDAY, Jan. 25 (HealthDay News) -- Active smoking has a modest effect on the risk of developing breast cancer, according to a study published in the Jan. 24 issue of the Archives of Internal Medicine.

Fei Xue, M.D., from Brigham and Woman's Hospital in Boston, and colleagues carried out a prospective study assessing smoking habits and breast cancer rates in participants in the Nurses' Health Study. From 1976 to 2006, 111,140 female nurses provided information on active smoking, and from 1982 to 2006, 36,017 female nurses were followed up for passive smoking.

The investigators identified 8,772 cases of invasive breast cancer. After adjusting for confounding factors, the hazard ratio (HR) of breast cancer was 1.06 for patients who had ever smoked, compared with those who had never smoked. Incidence of breast cancer was significantly linked to a higher quantity of present and past smoking, initiation of smoking at a younger age, longer duration of smoking, and more pack-years of smoking. Smoking prior to menopause, especially before a first birth, was associated with a slightly higher incidence of breast cancer, whereas smoking after menopause showed a trend toward an inverse association with breast cancer (HR, 0.93). No association was found between passive smoking, either in childhood or adulthood, and breast cancer incidence.

"Despite the extensive research on cigarette smoking in relation to breast cancer risk, this association remains controversial. Results from the present study suggest that the potential effect of active smoking on breast cancer risk is modest," the authors write.

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