Touillaud, Marina2023-12-052023-12-052001-12https://hdl.handle.net/11274/15601While diet may influence estrogen receptor (ER) status, no study has investigated the effect of phytoestrogen intake on this breast cancer prognostic factor. This case-case study examined ER status and usual pre-diagnostic phytoestrogen consumption of 93 premenopausal breast cancer patients. Data were collected from a 207-item food frequency questionnaire and abstracted from medical records. ER-status groups were similar in demographic and anthropometric characteristics, oral contraceptive use, and caloric intake. In univariate analyses, a low intake of genistein, the most potent isoflavone, was associated with increased risk of ER-negative compared to ER-positive breast cancer [odds ratio (OR) = 1.76, 95% confidence interval (CI) = 0.73 − 4.25], while the relationship was weaker for total isoflavones (OR = 1.03, 95% CI = 0.43 − 2.46). Low total phytosterol intake was associated with decreased risk of ER-negative cancer (OR = 0.57, 95% CI = 0.24 − 1.37). These findings suggest that phytoestrogens may influence ER status.en-USPremenopausal cancer patientBreast cancerPhytoestrogensThesis