@entity172 are known to be important in the growth of @entity0 in both pre and postmenopausal @entity1 . As the number of @entity0 @entity1 increases with age, the majority of @entity0 @entity1 are postmenopausal @entity1 . Although @entity172 are no longer made in the ovaries after menopause, peripheral tissues produce sufficient concentrations to stimulate @entity5 growth. As aromatase catalyzes the final and rate-limiting step in the biosynthesis of @entity172 , inhibitors of this enzyme are effective targeted therapy for @entity0 . Three aromatase inhibitors (AIs) are now FDA approved and have been shown to be more effective than the antiestrogen @entity440 and are well tolerated. AIs are now a standard treatment for postmenopausal @entity1 . AIs are effective in adjuvant and first-line metastatic setting. This review describes the development of AIs and their current use in @entity0 . Recent research focuses on elucidating mechanisms of acquired resistance that may develop in some @entity1 with long term AI treatment and also in innate resistance. Preclinical data in resistance models demonstrated that the crosstalk between ER and other signaling pathways particularly MAPK and PI3K/ @entity584 is an important resistant mechanism. Blockade of these other signaling pathways is an attractive strategy to circumvent the resistance to AI therapy in @entity0 . Several clinical trials are ongoing to evaluate the role of these novel targeted therapies to reverse resistance to AIs. Article from the special issue on 'Targeted Inhibitors'.

Aromatase, aromatase inhibitors, and XXXX .

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen', 'Estrogens', 'estrogens'] @entity1 :: ('9606', 'Species') :: ['women', 'patients'] @entity440 :: ('MESH:D013629', 'Chemical') :: ['tamoxifen'] @entity0 :: ('MESH:D001943', 'Disease') :: ['breast cancers', 'breast cancer'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity584 :: ('207', 'Gene') :: ['Akt']
@entity0 :: (MESH:D001943,Disease) :: ['breast cancer']
