ESR1 and breast cancer: To explore the prognostic significance of TWIST1 mRNA expression in primary breast cancer patients, we first performed Cox uni- and multivariate analyses (traditional factors in the multivariate analysis were; age, menopausal status, number of positive lymph nodes, tumor size, tumor grade, ER status, PGR status and ERBB2 status) for MFS, DFS and OS as a function of continuous TWIST1 mRNA expression levels.