title: Letrozole : in postmenopausal hormone-responsive early-stage breast cancer.
abstract: Letrozole is a highly selective, nonsteroidal, third-generation aromatase inhibitor approved for first-line and extended adjuvant therapy in postmenopausal women with hormone-responsive, early-stage breast cancer. Binding of letrozole to the haeme component of the cytochrome P450 subunit of aromatase inhibits estrogen biosynthesis throughout the body. As first-line adjuvant therapy in approximate, equals 8000 postmenopausal women with hormone-responsive, early-stage breast cancer, once-daily letrozole 2.5mg significantly prolonged disease-free survival (DFS; primary endpoint) and reduced the risk of relapse at distant sites relative to once-daily tamoxifen 20mg in the ongoing Breast International Group 1-98, double-blind, multinational trial. The median duration of follow-up for this primary core analysis was 25.8 months. Extended adjuvant therapy with once-daily letrozole 2.5mg significantly prolonged DFS relative to placebo treatment at a median follow-up of 30 months (primary endpoint) in the MA-17 trial in approximate, equals 5000 postmenopausal women who were disease free after 4.5-6 years of tamoxifen therapy for hormone-responsive, early-stage breast cancer. Letrozole treatment for up to 5 years was generally well tolerated in this clinical setting. As first-line treatment, relative to tamoxifen, letrozole was associated with a significantly lower incidence of venous thromboembolitic events, vaginal bleeding, hot flushes and night sweating, whereas the incidence of cardiac failure, bone fractures and arthralgia was higher in letrozole recipients.
authors.affiliation: Adis International Limited, Auckland, New Zealand. demail@adis.co.nz
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Scott
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Keam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D047072:Aromatase Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D018572:Disease-Free Survival; D006801:Humans; D000077289:Letrozole; D008297:Male; D008875:Middle Aged; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D009570:Nitriles / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D017698:Postmenopause; D016032:Randomized Controlled Trials as Topic; D020845:Selective Estrogen Receptor Modulators / Q000009:adverse effects / Q000627:therapeutic use; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use; D013923:Thromboembolism / Q000209:etiology; D014230:Triazoles / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D020246:Venous Thrombosis / Q000209:etiology
chemical_list: D000970:Antineoplastic Agents; D047072:Aromatase Inhibitors; D009570:Nitriles; D020845:Selective Estrogen Receptor Modulators; D014230:Triazoles; D013629:Tamoxifen; D000077289:Letrozole