This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gram, I. T. Articles by Weiderpass, E. Search for Related Content PubMed PubMed Citation Articles by Gram, I. T. Articles by Weiderpass, E.

Breast Cancer Risk Among Women Who Start Smoking as Teenagers

¹ Institute of Community Medicine, University of Tromsö, ² NIEHS, Epidemiology Branch, Research Triangle Park, North Carolina; ³ International Agency for Research on Cancer, ⁴ Institut National de la Santé et de la Recherche Médicale, Lyon, France; ⁵ Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; ⁶ Finish Cancer Registry, Liisankatu, Helsinki, Finland

Inger T. Gram, Institute of Community Medicine, University of Tromsö, N-9037 Tromsö, Norway. Phone: +47-7764-4816; Fax: +47-7764-4831. E-mail: inger.gram{at}ism.uit.no

Objective: To examine the effect of smoking on breast cancer risk in a large population-based cohort of women, many of whom started smoking as teenagers.

Methods: We followed 102,098 women, ages 30 to 50 years, completing a mailed questionnaire at recruitment to the Norwegian-Swedish Cohort Study in 1991/1992, through December 2000. We used Cox proportional hazard regression models to estimate relative risk (RR) of breast cancer associated with different measures of smoking initiation, duration, and intensity adjusting for confounding variables. We conducted analyses on the entire study population, among women who had smoked for at least 20 years, among nondrinkers, and separately for each country.

Results: Altogether, 1,240 women were diagnosed with incident, invasive breast cancer. Compared with never smokers, women who smoked for at least 20 years and who smoked 10 cigarettes or more daily had a RR of 1.34 (95% CI, 1.06-1.70). Likewise, those who initiated smoking prior to their first birth (1.27, 1.00-1.62), before menarche (1.39, 1.03-1.87), or before age 15 (1.48, 1.03-2.13) had an increased risk. In contrast, women who had smoked for at least 20 years, but started after their first birth, did not experience an increased breast cancer risk. The increased RR associated with smoking was observed among nondrinkers of alcohol, women with and without a family history of breast cancer, premenopausal and postmenopausal women, and in both countries.

Conclusion: Our results support the notion that women who start smoking as teenagers and continue to smoke for at least 20 years may increase their breast cancer risk.

Key Words: Smoking • breast cancer • incidence • cohort • teenager • age at first birth • alcohol • risk factors • epidemiology • women • Norway • Sweden

This article has been cited by other articles:

				M. Ha, K. Mabuchi, A. J. Sigurdson, D. M. Freedman, M. S. Linet, M. M. Doody, and M. Hauptmann Smoking Cigarettes before First Childbirth and Risk of Breast Cancer Am. J. Epidemiol., July 1, 2007; 166(1): 55 - 61. [Abstract] [Full Text] [PDF]

				J. Prescott, H. Ma, L. Bernstein, and G. Ursin Cigarette Smoking Is Not Associated with Breast Cancer Risk in Young Women Cancer Epidemiol. Biomarkers Prev., March 1, 2007; 16(3): 620 - 622. [Full Text] [PDF]

				P. D. Terry and M. Goodman Is the Association between Cigarette Smoking and Breast Cancer Modified by Genotype? A Review of Epidemiologic Studies and Meta-analysis. Cancer Epidemiol. Biomarkers Prev., April 1, 2006; 15(4): 602 - 611. [Abstract] [Full Text] [PDF]