Defining reference age as age at diagnosis for cases and age at interview for controls and using this as a proxy for menopausal status (<54 or ≥54 years), we further stratified our analysis on menopausal status; there was little evidence that the association with ER + /PR + breast cancer differed by menopausal status (premenopausal OR = 0.94, 95% CI 0.84–1.06, P = 0.31, postmenopausal OR = 0.86, 95% CI 0.80–0.93, P = 0.0001, Phet = 0.28). This evidence concerns the gene PGR and breast cancer.