Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort
Couplée à une étude cas-témoins, cette étude de cohorte incluant 1 125 femmes non malades évalue l'association entre la densité mammaire et d'autres facteurs de risque de cancer du sein (consommation d'alcool, parité, utilisation d'un traitement hormonal substitutif de la ménopause, histoire familiale de cancer, etc.)
Background: We investigated associations of known breast cancer risk factors with breast density, a well-established and very strong predictor of breast cancer risk. Methods: This nested case–control study included breast cancer-free women, 265 with high and 860 with low breast density. Women were required to be 40–80 years old and should have a body mass index (BMI) <35 at the time of the index mammogram. Information on covariates was obtained from annual questionnaires. Results: In the overall analysis, breast density was inversely associated with BMI at mammogram (P for trend<0.001), and parity (P for trend=0.02) and positively associated with alcohol consumption (ever vs never: odds ratio 2.0, 95% confidence interval 1.4–2.8). Alcohol consumption was positively associated with density, and the association was stronger in women with a family history of breast cancer (P<0.001) and in women with hormone replacement therapy (HRT) history (P<0.001). Parity was inversely associated with density in all subsets, except premenopausal women and women without a family history. The association of parity with density was stronger in women with HRT history (P<0.001). Conclusion: The associations of alcohol and parity with breast density appear to be in reverse direction, but stronger in women with a family history of breast cancer and women who ever used HRT.