STEROID-RECEPTOR EXPRESSION IN ENDOMETRIA FROM WOMEN TREATED WITH TAMOXIFEN

Breast cancer patients receiving tamoxifen (Tam) are at an increased r isk for developing endometrial carcinomas, possibly due to the partial estrogenic effect of Tam on endometrial cells. Progestational therapy has not routinely been included in Tam regimens. It was our aim to de termine the presence of estrogen receptors (ERs) and progesterone rece ptors (PRs) in normal and abnormal endometria from postmenopausal wome n with breast cancer who were treated with Tam. Standard immunohistoch emical staining of ERs and PRs was performed on paraffin sections from formalin-fixed uterine curettings or hysterectomy specimens from 40 p atients who had received 20-40 mg of Tam daily for a minimum of 3 mont hs. For comparison, normal endometria from 20 women who had not receiv ed Tam (11 premenopausal, 9 postmenopausal) were also studied for ER a nd PR expression. Staining was evaluated using semiquantitative immuno reactivity scores (IRS) ranging from 0 (negative) to 12 (strongly posi tive). In the group of patients receiving Tam, ERs and PRs were detect ed in the nuclei of glandular cells in 24/24 cases of endometrial atro phy (ER/PR-IRS, 2-12), in 8/8 endometrial polyps (ER-IRS, 6-12; PR-IRS , 4-12), in 4/4 adenomatous endometrial hyperplasias (ER-IRS, 3-8; PR- IRS, 1-12), and in 4/4 well-differentiated endometrioid adenocarcinoma s (ER-IRS, 2-12; PR-IRS, 6-8). Of the 11 endometria from premenopausal patients who had not received Tam, 8 were ER+/PR+ (ER-IRS, 1-12; PR-I RS, 1-12), 1 was ER+/PR- (ER-IRS, 3; PR-IRS, 0), 1 was ER-/PR+ (ER-IRS , 0; PR-IRS, 2), and 1 was ER-/PR- (ER/PR-IRS, 0). Among 9 atrophic en dometria from women not treated with Tam, 6 were ER+/PR+ (ER-IRS, 4-12 ; PR-IRS, 3-6), 1 was ER+/PR- (ER-IRS, 4; PR-IRS, 0), and 2 were ER-/P R- (ER/PR-IRS, 0). The consistent finding of ER and PR expression in e ndometria from postmenopausal women receiving Tam further supports the suspected estrogenic effect exerted by Tam on endometrial cells. Prog estational therapy could be beneficial in the prevention of Tam-induce d abnormal endometrial proliferations. (C) 1998 Academic Press.