Author(s)

Lloyd H. Smith, Gary Leiserowitz, Guibo Xing, John Bishop

Department of Obstetrics, Gynecology and Pathology, UC Davis School of Medicine Sacramento, Sacramento, USA.

Objective: To determine if short-term treatment with Femara (letrozole) induces measurable reduction in tumor Ki67 expression in postmenopausal women with FIGO grade 1 and 2 endometrial carcinoma. Methods: In this non-randomized prospective study, 12 patients were given Femara (letrozole) 2.5 mg daily for approximately 3 weeks prior to planned hysterectomy for FIGO grade 1 or 2 endometrial carcinoma. A group of 12 demographically similar patients were enrolled as no-treatment controls. Ki67 expression in tumor cells was quantitated by immunohistochemistry with mechanical scanning within the initial endometrial biopsy and compared to that in the hysterectomy specimen for each patient in the treatment and control groups. Results: The treatment and control groups were similar in age, tumor grade and FIGO stage. When “aromatase inhibitor responsiveness” was defined as proportionate decline in Ki67% stained tumor cells of at least 70% between the pre-treatment endometrial biopsy and post-treatment hysterectomy specimens, 5 of 12 patients were found to be “responsive” in the treatment group with none of the controls fulfilling these criteria. Conclusion: Femara (letrozole) 2.5 mg daily for approximately 3 weeks induced a significant reduction in tumor cell Ki67 expression among 5 of 12 (41%) postmenopausal women with FIGO grade 1 or 2 endometrial carcinoma. We postulate that Ki67 may be a useful marker during aromatase inhibitor medical treatment of patients with endometrial cancer who are not candidates for surgical treatment.

Endometrial Carcinoma; Aromatase Inhibitor; Letrozole; Ki67

Smith, L. , Leiserowitz, G. , Xing, G. and Bishop, J. (2013) Short-term Femara (letrozole) treatment and suppression of Ki67 expression in postmenopausal endometrial carcinoma. Open Journal of Obstetrics and Gynecology, 3, 347-351. doi: 10.4236/ojog.2013.33064.