The role of hormone replacement therapy in endometrial polyp formation

To evaluate the iatrogenic effect of different protocols of hormone replacement therapy (HRT) on endometrial polyp formation adjusting for the confounding effects of other factors such as age, parity, weight and menopausal status at menopause.

Out of 2685 menopause patients 375 (13.9%) eligible patients were enrolled. Patients were randomized to three HRT types and three equal groups were formed. The first group received Premelle 2.5 mg (Group-I) (0.625 mg conjugated estrogen + 2.5 mg medroxyprogestorone), the second received Kliogest (Group-II) (2 mg estradiol + 1 mg norethisterone) and the last received Livial (Group-III) (2.5 mg tibolone) at least for 36 months without giving a break. After the first 18 months patients had their first office hysteroscopy and it was repeated in every 6 months until the end of third year to find out new and recurrent endometrial polyps.

Multiple regression analysis revealed that the type of HRT, late menopause and obesity increased the occurrence of endometrial polyps. In Group-I five polyps, in Group-II ten polyps and in Group-III two polyps were detected. There were significant differences between G-II and G-I and G-II and G-III (P < 0.05), but there was no significant difference between G-I and G-III (P > 0.05). 82.3% of the polyps were detected in the third and fourth hysteroscopic examinations. Endometrial polyp recurrence was encountered in 4 (23.5%) patients, 1 in G-I and 3 in G-II without a significant difference (P > 0.05). No malignancy was detected in any of the specimen.

We observed that endometrial polyp formation may be dependent on the type and dosage of the estrogen and progestogen. Especially a progestogen with high antiestrogenic activity may play an important preventive role in the development of endometrial polyps.