Neoadjuvant therapy of endometrial cancer with the aromatase inhibitor letrozole: endocrine and clinical effects.

Objective: To investigate the short-term hormonal and clinical effects of the aromatase inhibitor letrozole (Femara) in patients with endometrial cancer.

Materials And Methods: Ten previously untreated, post-menopausal patients (mean age 59 years) with endometrial cancer, predominantly stage I disease, received letrozole 2.5mg per day for 14 days before surgery. Clinical, sonographic, morphologic, cytologic, and hormonal-metabolic parameters (blood estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), glucose, and cholesterol by radioimmunoassay, enzyme immune assay, or enzyme-colorimetric methods; tumor progesterone receptors by ligand-binding assay; and aromatase activity by 3H-water release assay) were evaluated before and after treatment.

Results: Treatment was well-tolerated in all patients. In two patients, pain relief in the lower part of the belly and/or decrease in intensity of uterine discharge was reported. In the three cases, substantial decreases in endometrial M-echo (ultrasound) signal were noted; the mean value of this parameter after treatment was 31.1% lower than before treatment. Blood estradiol concentration decreased by an average of 37.8% after letrozole therapy, and tumor progesterone receptor levels and aromatase activity decreased by 34.4 and 17.5%, respectively. Treatment with letrozole did not influence surgery.

Conclusions: These data show that short-term treatment with letrozole in the neoadjuvant setting resulted in some positive clinical changes. Longer-term and larger-scale trials of neoadjuvant letrozole in endometrial cancer are warranted.