The natural history of @entity0 is closely linked with @entity172 . These hormones influence both risk to the disease and growth of many established @entity5 . Consequently, measures that either inhibit the synthesis or block the mechanism of action of @entity172 are attractive strategies for therapeutic intervention. This is particularly true in postmenopausal @entity1 in whom hormone responsiveness is common and @entity172 synthesis is primarily sited peripherally in adipose tissue, muscle and breast tissue, rather than in the ovaries as in premenopausal @entity1 . In terms of inhibiting production, the most specific effects are best achieved by blocking the last step in biosynthesis, the conversion of @entity3800 to @entity172 by the @entity1446 -containing enzyme, aromatase. Two major classes of aromatase inhibitors have been developed and are currently in clinical use. Type I steroidal drugs include @entity19836 and @entity17082 ; they are @entity342 substrate analogues that bind competitively but irreversibly to the enzyme and have been marketed as "inactivators." Type II nonsteroidal inhibitors such as @entity13558 and @entity4672 are @entity5627 ; they bind reversibly to the enzyme and fit into the substrate binding site, such that @entity5638 nitrogens interact with the @entity1446 prosthetic group. This type of association provides exquisite potency for and specificity against the aromatase enzyme. These agents represent several generations of development, with each step in the evolution producing an increase in both potency and specificity. The latest aromatase inhibitors are drugs of immense potential that will undoubtedly play a major role in the management of postmenopausal @entity1 with hormone-dependent @entity0 . They also represent tools by which to elucidate the roles of both aromatase and @entity172 in the development and growth of @entity0 .

Aromatase inhibitors: mechanism of action and role in the treatment of XXXX .

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen', 'estrogens'] @entity1 :: ('9606', 'Species') :: ['women'] @entity4672 :: ('MESH:C067431', 'Chemical') :: ['letrozole'] @entity0 :: ('MESH:D001943', 'Disease') :: ['breast cancer'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumors'] @entity17082 :: ('MESH:C056516', 'Chemical') :: ['exemestane'] @entity19836 :: ('MESH:C014594', 'Chemical') :: ['formestane'] @entity342 :: ('CHEBI:50113', 'Chemical') :: ['androgen'] @entity13558 :: ('MESH:C090450', 'Chemical') :: ['anastrozole'] @entity5627 :: ('MESH:D014230', 'Chemical') :: ['triazoles'] @entity3800 :: ('MESH:D000728', 'Chemical') :: ['androgens'] @entity5638 :: ('CHEBI:68452', 'Chemical') :: ['azole'] @entity1446 :: ('MESH:D006418', 'Chemical') :: ['heme']
@entity0 :: (MESH:D001943,Disease) :: ['breast cancer']
