this study was designed to compare the effect of clomiphene and letrozole in ovulatory stimulation in infertile women under intrauterine insemination who referred to mahdiyeh infertility clinic during 2008-2009. 106 infertile women were randomly divided into two equal groups. patients were treated with 5 mg of letrozole daily (in letrozole group) or 100 mg of clomiphene citrate daily (in clomip...

BACKGROUND The aromatase inhibitor letrozole, as compared with tamoxifen, improves disease-free survival among postmenopausal women with receptor-positive early breast cancer. It is unknown whether sequential treatment with tamoxifen and letrozole is superior to letrozole therapy alone. METHODS In this randomized, phase 3, double-blind trial of the treatment of hormone-receptor-positive breas...

Using the intratumoral aromatase xenograft model, we have observed that despite long-lasting growth inhibition, tumors eventually begin to grow during continued letrozole treatment. In cells isolated from these long-term letrozole-treated tumors (LTLT-Ca), estrogen receptor-alpha (ERalpha) levels were decreased, whereas signaling proteins in the mitogen-activated protein kinase cascade were up-...

background: clomiphene citrate (cc) an agonist and antagonist of estrogen, is the first line treatment in ovarian stimulation. anti-estrogenic effect of cc in endometrial thickness and cervical mucus has negative effect on pregnancy rate. letrozole is an aromatase inhibitor has been seen that has acceptable pregnancy rate compared to cc. objective: the aim of this study was to compare the effic...

Using a hormone-dependent xenograft model, we established that loss of response to letrozole was accompanied by upregulation of the Her-2/mitogen-activated protein kinase (MAPK) pathway and downregulation of estrogen receptor alpha (ERalpha) and aromatase activity. In our previous study, we showed that stopping letrozole treatment or adding trastuzumab could reverse acquired resistance. In this...

Letrozole (Femara; Novartis Pharmaceuticals Corp., East Hanover, NJ) is a nonsteroidal inhibitor of aromatase enzyme complex. It inhibits the peripheral conversion of circulating androgens to estrogens. In postmenopausal women, letrozole decreases plasma concentrations of estradiol, estrone, and estrone sulfate by 75-95% from baseline with maximal suppression achieved within 2-3 days of treatme...

BACKGROUND The purpose of this study was to appraise the possible adverse effects of quercetin against the aromatase inhibitor letrozole-induced developmental toxicity potential in male Wistar rats. METHODS Control male albino rats were received vehicles used for flavonoids and vehicle used for letrozole. The rats in the first experimental group received letrozole at 0.04 mg/kg body weight (b...

PURPOSE The purpose of this study was to evaluate and compare the effects of the antiestrogen tamoxifen and the aromatase inhibitor letrozole on tumor growth, serum hormones, uterine weight, body composition, and bone characteristics in mice. EXPERIMENTAL DESIGN Human estrogen-dependent breast cancer cells stably transfected with the aromatase gene (MCF-7CA cells) were inoculated in Matrigel ...

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder in young women which has different clinical consequences. This study was conducted to evaluate the outcome of long or extended letrozole therapy for induction of ovulation in patients with polycystic ovary syndrome (PCOS). Materials and Methods: This prospective controlled study was conducted in a university hospital on...

BACKGROUND MA.17 evaluated letrozole or placebo after 5 years of tamoxifen and showed significant improvement in disease-free survival (DFS) for letrozole [hazard ratio (HR) 0.57, P = 0.00008]. The trial was unblinded and placebo patients were offered letrozole. PATIENTS AND METHODS An intent-to-treat analysis of all outcomes, before and after unblinding, on the basis of the original randomiz...