Significant increase of benign endometrial cells on Papanicolaou smears in women using hormone replacement therapy

Abstract

OBJECTIVE: To determine the prevalence of benign endometrial cells on Papanicolaou smears from postmenopausal women and to compare the prevalence and histologic diagnosis in women who use hormone replacement therapy (HRT) with those who do not. METHODS: Papanicolaou smear diagnoses from postmenopausal women and women over age 50 between April 1995 and December 1998 were retrieved and linked with follow-up smears and biopsies. Hormone status of women with benign endometrial cells smears was obtained from requisition forms or phone conversation with primary care providers. All surgical pathology material as well as Papanicolaou smears from women subsequently diagnosed with endometrial adenocarcinoma were reviewed. Relative prevalence with 95% confidence intervals was determined. RESULTS: A total of 589 of 52,662 Papanicolaou smears from postmenopausal women were diagnosed with benign endometrial cells, a prevalence of 1.1%. Also, HRT was reported in 16,073 (31%), no HRT was reported in 33,170 (63%), and hormone status was unknown in 3379 (6%). Smears from 245 HRT users, 324 nonusers, and 20 with unknown hormone status were diagnosed with benign endometrial cells. There was a significant increased prevalence of benign endometrial cells in women on HRT compared with nonusers (relative prevalence 1.56, 95% confidence interval 1.32, 1.84, P < .001). Among 436 women with known hormonal status and follow-up, 12 (2.7%) had endometrial carcinoma, three (1.5%) in HRT users and nine (3.7%) in nonusers ( P = .175). In addition, HRT users had significantly less abnormal endometrial histology than non-HRT users (2.6% versus 7.4%, P = .025). CONCLUSION: We found that HRT is significantly associated with an increased prevalence of benign endometrial cells on Papanicolaou smears. Women on HRT who have benign endometrial cells on their Papanicolaou smears, however, have less abnormal endometrial histology compared with women not using HRT who have benign endometrial cells on their Papanicolaou smears.