Abstract:

Objective To investigate the effects of tamoxifen(TAM) on expression of oestrogen receptors(ER),progesterone receptors(PR)and Ki-67 antigen in postmenopausal endometrium.Methods Forty-six postmenopausal breast cancer patients receiving 20 mg/d TAM for at least six months were examined by hysteroscopy and endometrial biopsy,and eighteen age-matched,non-hormonally treated patients with atrophic endometrium post vaginal hysterectomy because of uterine prolapse served as control groups.Immunohistochemical studies for the expression of ER,PR and Ki-67 antigen in endometrium were performed.Results There were significantly increased levels of expression of PR((0.46±)0.05 vs 0.35±0.06,P=0.028) in glandular epithelium in tamoxifen-associated endometrium compared with atrophic endometrium.Also,Ki-67 antigen was expressed more frequently in glandular epithelium in the tamoxifen samples(15.41±4.83 vs 9.05±5.52,P=0.009).The expression of ER in glandular epithelium was higher but did not differ statistically between tamoxifen-associated endometrium and atrophic endometrium(0.47±0.06 vs 0.43±0.06,P=0.063).Conclusion In postmenopausal women tamoxifen exerts a proliferative effect on the endometrium,as measured by Ki-67 antigen.The tamoxifen-associated changes in endometrial PR support an estrogenic effect that is independent of histological diagnosis and duration.This may contribute to the pathogenesis of tamoxifen-associated polyps and carcinomas.

Key words: tamoxifen, endometrium, oestrogen receptors, progesterone receptors, Ki-67 antigen