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Another Good Reason Not to Smoke

Friday, January 28, 2011 // Uncategorized

Smoking is associated with a host of health ills including a risk of cardiovascular disease and an increased risk of cancer of the lung, bladder and mouth.  This is an alert from Journal Watch that adds a cancer risk to the list.  Following it is the abstract from The Archives of Internal Medicine.

Early Cigarette Smoking Associated with Breast Cancer
Young female patients who smoke may benefit from knowing that early smoking is associated with a modest increase in breast cancer risk, according to an Archives of Internal Medicine study.
Researchers analyzing updated data from the Nurses’ Health Study report that they have confirmed their 2002 finding of a slight elevation in breast cancer risk associated with smoking. During some 3 million person-years of follow-up between 1976 and 2006, women who smoked more than 25 cigarettes per day for more than 35 years and began smoking before age 18 had a hazard ratio for invasive breast cancer of 1.25, compared with never-smokers.
The effect was stronger when smoking began before the woman’s first birth and before menopause. Postmenopausal smoking was associated with a slightly decreased risk. There was no apparent increased risk from exposure to secondhand smoke.

Cigarette Smoking and the Incidence of Breast Cancer
Fei Xue, MD, ScD; Walter C. Willett, MD, DrPH; Bernard A. Rosner, PhD; Susan E. Hankinson, ScD; Karin B. Michels, ScD, PhD

Arch Intern Med. 2011;171(2):125-133. doi:10.1001/archinternmed.2010.503

Background Tobacco smoke contains carcinogens, which may increase the risk of breast cancer (BC). Conversely, cigarette smoking also has antiestrogenic effects, which may reduce the risk of BC. The association between smoking and BC remains controversial.

Methods Prospective cohort study of 111 140 participants of the Nurses’ Health Study from 1976 to 2006 for active smoking and 36 017 women from 1982 to 2006 for passive smoking.

Results During 3 005 863 person-years of follow-up, 8772 incident cases of invasive BC were reported. After adjustment for potential confounders, the hazard ratio (HR) of BC was 1.06% (95% confidence interval [CI], 1.01%-1.10%) for ever smokers relative to never smokers. Breast cancer incidence was associated with a higher quantity of current (P for trend = .02) and past (P for trend = .003) smoking, younger age at smoking initiation (P for trend = .01), longer duration of smoking (P for trend = .01), and more pack-years of smoking (P for trend = .005). Premenopausal smoking was associated with a slightly higher incidence of BC (HR, 1.11; 95% CI, 1.07-1.15 for every increase of 20 pack-years), especially smoking before first birth (1.18; 1.10-1.27 for every increase of 20 pack-years). Conversely, the direction of the association between postmenopausal smoking and BC was inverse (0.93; 0.85-1.02 for every increase of 20 pack-years). Passive smoking in childhood or adulthood was not associated with BC risk.

Conclusion Active smoking, especially smoking before the first birth, may be associated with a modest increase in the risk of BC.

Author Affiliations: Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics and Gynecology (Drs Xue and Michels), and the Channing Laboratory, Department of Medicine (Drs Willett, Rosner, Hankinson, and Michels), Brigham and Woman’s Hospital, and Harvard Medical School, Boston, Massachusetts; and Departments of Epidemiology (Drs Xue, Willett, Rosner, Hankinson, and Michels), Nutrition (Dr Willett), and Biostatistics (Dr Rosner), Harvard School of Public Health, Boston.

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