Abstract PR-05: Exposure to tobacco smoke from husband and breast cancer risk in Japanese women
Authors: Wada Keiko , Nakamura Kozue , Tamai Yuya , Tsuji Michiko , Kawachi Toshiaki , Nagata Chisato 
Published: January 2014

Abstract
Background and purpose: Although experimental studies have shown that tobacco smoke or its compound might induce mammary carcinogenesis, the associations of active and passive smoking with the risk of breast cancer have been inconclusive in epidemiological studies. We examined whether their own and their husbands' smoking status were associated with the risk of breast cancer in a prospective cohort study.
Study subjects and methods: Subjects were members from a population-based cohort study, Takayama study. Participants were the residents of Takayama city, Gifu, Japan, aged 35 years or older in 1992. Participant rate was 85.3 %. The follow-up was conducted from the time of baseline study (September 1, 1992) through the end of March in 2008. The cancer incidence was mainly confirmed through regional population-based cancer registries. Breast cancer was defined as code C50 according to the International Classification of Diseases, 10th Revision (ICD-10). Information about smoking was gotten through a self-administered questionnaire. Smokers were defined as people who had smoked a total of 20 packs of cigarettes in their life. Using Cox proportional hazards model, the associations between subjects' smoking status at the base line and breast cancer incidence were assessed after adjustments for age, BMI, physical activity, alcohol consumption, education, age at menarche, age at first delivery, menopausal status, number of child and history of hormone replacement therapy. Similarly, the associations of their husbands' smoking status with breast cancer incidence were examined after additional adjustments for their own smoking status. Among 17,125 women enrolled in the baseline survey, 15,719 women were included for the analyses.
Results: During a total of 219,101 person-years of follow-up, 175 women had developed breast cancer. In the multivariate-adjusted model, their own smoking was not associated with the risk of breast cancer. Compared to women whose husband was never smokers, those whose husbands had smoked for 31 years or more in their life had significantly higher hazard ratios of breast cancer. Similarly, the hazard ratios of breast cancer were significantly higher among women whose husband was current smoker of 21 cigarettes or more. When subjects were limited to never smokers, the results were not substantially altered.
Conclusion: These results suggested that exposure to tobacco smoke from their husband might increase the risk of breast cancer.
Acknowledgements: The authors thank Dr. Hori A, Dr. Takeyama N, Kumiai Kousei Hospital; Dr. Tanahashi S, Dr. Matsushita S, Dr. Tokimitsu N, Takayama Red Cross Hospital, for their major contribution to the data collection of the Takayama study.
This abstract is also presented as Poster B83.
Citation Format: Keiko Wada, Kozue Nakamura, Yuya Tamai, Michiko Tsuji, Toshiaki Kawachi, Chisato Nagata. Exposure to tobacco smoke from husband and breast cancer risk in Japanese women. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr PR-05.