Passive Smoking and Risk of Breast Cancer in the California Teachers Study

Northern California Cancer Center, Berkeley, 94704, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.13). 12/2009; 18(12):3389-98. DOI: 10.1158/1055-9965.EPI-09-0936
Source: PubMed


Although recent reviews have suggested active smoking to be a risk factor for breast cancer, the association with passive smoke exposure remains controversial. This risk association was explored in a large prospective study of women, the California Teachers Study.
Detailed lifetime information on passive smoke exposure by setting (home, work, or social) and by age of exposure was collected in 1997 from 57,523 women who were lifetime nonsmokers and had no history of breast cancer. In the ensuing decade, a total of 1,754 women were diagnosed with invasive breast cancer. Cox proportional hazards models were fit to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) associated with several lifetime passive smoke exposure metrics.
For all breast cancer, measures of higher lifetime passive smoking intensity and duration were associated with nonstatistically significant HRs of 1.11 to 1.14. For postmenopausal women, HRs for lifetime low, medium, and high cumulative exposure were 1.17 (95% CI, 0.91-1.49), 1.19 (95% CI, 0.93-1.53), and 1.26 (95% CI, 0.99-1.60). For women exposed in adulthood (age > or =20 years), risk was elevated at the highest level of cumulative exposure (HR, 1.18; 95% CI, 1.00-1.40), primarily among postmenopausal women (HR, 1.25; 95% CI, 1.01-1.56). A statistically significant dose response was detected when analysis was restricted to women with moderate to high levels of passive smoke exposure.
These results suggest that cumulative exposures to high levels of sidestream smoke may increase breast cancer risk among postmenopausal women who themselves have never smoked tobacco products.

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Available from: Joan Largent, Oct 06, 2014
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    • "Evidence from recent systematic reviews and independent studies demonstrates a causal link between cigarette smoking at a young age and an increased risk for premenopausal breast cancer (Bjerkaas et al., 2013; Collishaw et al., 2009; Dossus et al., 2014; Gantz & Johnson, 2014; Johnson, 2005, 2012). In addition to active smoking, longterm exposure to second-hand smoke is also associated with an increased risk for breast cancer among never smokers (Collishaw et al., 2009; Reynolds et al., 2009). Physiological mechanisms that have been proposed to explain the link between exposure and increased breast cancer risk are based on research demonstrating that growing and differentiating mammary tissue, as occurs during puberty and pregnancy, is especially vulnerable to the carcinogens found in cigarette smoke (Innes & Byers, 2001; Lash & Aschengrau, 1999). "
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    ABSTRACT: Tobacco exposure during periods of breast development has been shown to increase risk of premenopausal breast cancer. An urgent need exists, therefore, to raise awareness among adolescent girls about this new evidence, and for adolescent girls and boys who smoke to understand how their smoking puts their female peers at risk for breast cancer. The purpose of this study was to develop two youth-informed, gender specific YouTube-style videos designed to raise awareness among adolescent girls and boys about tobacco exposure as a modifiable risk factor for breast cancer and to assess youths’ responses to the videos and their potential for inclusion on social media platforms. Both videos consisted of a combination of moving text, novel images, animations, and youth-friendly music. A brief questionnaire was used to gather feedback on two videos using a convenience sample of 135 youth in British Columbia, Canada. The overall positive responses by girls and boys to their respective videos and their reported interest in sharing these videos via social networking suggests that this approach holds potential for other types of health promotion messaging targeting youth. The videos offer a promising messaging strategy for raising awareness about tobacco exposure as a modifiable risk factor for breast cancer. Tailored, gender-specific messages for use on social media hold the potential for cost-effective, health promotion and cancer prevention initiatives targeting youth.
    Collegian Journal of the Royal College of Nursing Australia 06/2014; 21(2). DOI:10.1016/j.colegn.2014.04.002 · 1.18 Impact Factor
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    • "Information on parity, duration of breastfeeding, and active smoking history was obtained from self-administered questionnaires completed when the CTS cohort was established in 1995–1996, and information on the source, setting (household, workplace, and social), timing, and dose of passive smoking exposures was obtained from a second survey mailed to CTS participants in 1997. For non smokers, we used a measure of lifetime intensity-years of passive smoking calculated by multi plying a qualitative description of smoke intensity (1 = a little smoky, 2 = fairly smoky, or 3 = very smoky) by duration of exposure in years (Reynolds et al. 2009). Current age, usual diet, and alcohol consumption during the past year, weight, height, and current residential address were obtained from substudy participants at the time of urine sample collection in 2000. "
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    Environmental Health Perspectives 04/2013; 121(6). DOI:10.1289/ehp.1205524 · 7.98 Impact Factor
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    • "In addition, the association between secondhand smoking and breast cancer among younger, primarily premenopausal women who have never smoked was consistent with causality [9]. These conclusions were further supported by other recent findings [10] [11] [12]. "
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