Journal of Cancer Epidemiology
Volume 2009 (2009), Article ID 748367, 11 pages
doi:10.1155/2009/748367
Research Article
Weight History, Smoking, Physical Activity and Breast Cancer Risk among French-Canadian Women Non-Carriers of More Frequent BRCA1/2 Mutations
1Department of Nutrition, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
2Unité de recherche en épidémiologie, Centre de recherche, Centre Hospitalier de l'Université de Montréal (CHUM)-Hôtel-Dieu, Montreal, QC, Canada
3Centre de recherche, Institut Universitaire de Geriatrie de Montreal, Montreal, QC, Canada
4Service de Médecine Génique, Département de Médecine, Centre de Recherche du CHUM, Université de Montréal, QC, Canada
5Département de Chirurgie, Centre Hospitalier de l'Université de Montréal (CHUM)-Hôtel-Dieu, Montreal, QC, Canada
6Women's College Research Institute, Women's College Hospital, University of Toronto, Toronto, ON, Canada
Received 16 September 2008; Revised 26 January 2009; Accepted 26 February 2009
Academic Editor: Paolo Boffetta
Copyright © 2009 Vishnee Bissonauth et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Several lifestyle factors play a significant role in determining an individual's risk of breast cancer. Many of them could be modified to protect against the malignancy. A nested case-control study was conducted to examine the association between selected lifestyle factors and non-BRCA-related breast cancer risk among French-Canadian women. Some 280 women with breast cancer and who were nongene carriers of mutated BRCA gene were recruited as cases. Another 280 women, without any cancer and nongene carriers of mutated BRCA gene served as controls. A tested lifestyle questionnaire was interviewer administered to incident cases to obtain information on weight history, smoking, physical activity, and other lifestyle risk factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated in logistic regression models.
Comparing cases to controls, breast cancer risk was higher among subjects who reached their maximum body mass index (BMI) at an older age (>50 years) (OR=2.83; 95% CI: 2.34–2.91). A positive association was noted between breast cancer risk and weight gain of >34 lbs compared to weight gain of ≤15 lbs, since the age of 20 (OR=1.68; 95% CI: 1.10–2.58). Weight gain of >24 lbs compared to weight gain of ≤9 lbs, since the age of 30 also resulted in the same relationship (OR=1.96; 95% CI: 1.46–3.06). Similarly, since the age of 40, weight gain of >12 lbs compared to weight gain of ≤1 lb was associated with increased breast cancer risk (OR=1.91; 95% CI: 1.53–2.66). Women who smoked >9 pack-years of cigarettes had a 59% higher breast cancer risk (P=.05). Subjects who engaged in >24.8 metabolic-equivalent- (MET-) hours per week compared to ≤10.7 MET-hours per week of moderate physical activity had a 52% (P=.01) decreased risk and total physical activity between 16.2 and 33.2 MET-hours per week compared to ≤16.2 MET-hours per week, resulted in a 43% (P=.05) lower risk of breast cancer. In conclusion, weight history did affect breast cancer risk. Moreover, smoking appeared to raise the risk, whereas moderate physical activity had a protective effect.