Phytoestrogen intake from foods, during adolescence and adulthood, and risk of breast cancer by estrogen and progesterone receptor (ERPR) tumour subgroup among Ontario women
A partir des données du registre de l'Ontario des cancers, cette étude analyse l'association entre la consommation de phytoestrogènes d'origine alimentaire pendant l'adolescence et l'âge adulte et le risque de cancer du sein, en fonction du sous-type de la tumeur
Phytoestrogen intake may reduce breast cancer risk and limited evidence suggests this association may hold for hormone receptor positive tumours only. The study aims were to assess whether the association between phytoestrogen intake during adolescence and adulthood and breast cancer risk varies by estrogen and progesterone receptor (ERPR) tumour subgroup. Cases were identified from the Ontario Cancer Registry (2002-2003) and ERPR status was ascertained from pathology reports for 81% of cases (n=2438). Controls were identified through random digit dialling of Ontario households (n=3370). Published phytoestrogen food values were applied to food frequency questionnaire responses to assess isoflavone, lignan, and total phytoestrogen intake, during adolescence and adulthood. Polytomous multivariate logistic regression was used to estimate adjusted odds ratios (ORs) for association between phytoestrogen intake and breast cancer risk by hormone receptor ERPR tumour subgroups. Among premenopausal women, few associations were observed for adolescent or adult phytoestrogen intake across all tumour subgroups. Among postmenopausal women, adolescent phytoestrogen intake (isoflavone, lignan, total) was associated with reduced risk across all hormone receptor subgroups; however, statistical significance was most consistent within the ER+PR+ subgroup. For example, ER+PR+ postmenopausal breast cancer risk was associated with adolescent phytoestrogen intake (highest versus lowest: OR = 0.79; 95% CI: 0.65, 0.96)). Among all women and postmenopausal women, ORs for high adult lignan intake were all below 1.0 within each tumour subgroup, suggesting reduced breast cancer risk, although none reached statistical significance. In conclusion, adolescent phytoestrogen intake was associated with reduced postmenopausal breast cancer, particularly for ER+PR+ tumour subgroup.