Dietary patterns and breast cancer risk: a study in 2 cohorts
Menée à partir des données de deux études de cohorte incluant au total 53 827 femmes dont 4 756 femmes ayant développé un cancer du sein, cette étude évalue, en fonction de l'origine ethnique et du statut ménopausique, l'association entre deux types de régimes alimentaires, l'un basé sur la consommation de fruits et de légumes, l'autre sur la consommation de viandes et de féculents, et le risque de développer la maladie
Background : Evidence for a role of dietary risk factors in the cause of breast cancer has been inconsistent. The evaluation of overall dietary patterns instead of foods in isolation may better reflect the nature of true dietary exposure in a population. Objective : We used 2 cohort studies to identify and confirm associations between dietary patterns and breast cancer risk. Design : Dietary patterns were derived by using a principal components factor analysis in 1097 breast cancer cases and an age-stratified subcohort of 3320 women sampled from 39,532 female participants of the Canadian Study of Diet, Lifestyle and Health (CSDLH). We conducted a confirmatory factor analysis in 49,410 subjects in the National Breast Screening Study (NBSS) in whom 3659 cases of incident breast cancer developed. Cox regression models were used to estimate HRs for the association between derived dietary factors and risk of breast cancer in both cohorts. Results : The following 3 dietary factors were identified from the CSDLH: healthy, ethnic, and meat and potatoes. In the CSDLH, the healthy dietary pattern was associated with reduced risk of breast cancer (HR for high compared with low quintiles: 0.73; 95% CI: 0.58, 0.91; P-trend = 0.001), and the meat and potatoes dietary pattern was associated with increased risk in postmenopausal women only (HR for high compared with low quintiles: 1.26; 95% CI: 0.92, 1.73; P-trend = 0.043). In the NBSS, the association between the meat and potatoes pattern and postmenopausal breast cancer risk was confirmed (HR: 1.31; 95% CI: 0.98, 1.76; P-trend = 0.043), but there was no association between the healthy pattern and risk of breast cancer. Conclusion : Adherence to a plant-based diet that limits red meat intake may be associated with reduced risk of breast cancer, particularly in postmenopausal women.