PGR and breast neoplasm: Previous studies have suggested that patients with ER-positive and PgR-positive breast tumours have a more active ER and have demonstrated that these patients are more likely to benefit from endocrine therapy compared with patients with ER-positive/PgR-negative tumours (Wittliff, 1984; Jakesz et al, 2002; Bardou et al, 2003).