A randomised controlled trial of prophylactic levonorgestrel intrauterine system in tamoxifen-treated women

Objective  To study the prophylactic use of levonorgestrel intrauterine system (LNG-IUS) in the prevention of endometrial pathology in women having breast cancer treated with tamoxifen.
Design  Randomised controlled trial.
Setting  A tertiary teaching hospital.
Population  One hundred and thirteen women (66 premenopausal/47 postmenopausal) who required adjuvant tamoxifen for breast cancer after the completion of postoperative radiotherapy and chemotherapy.
Methods  Women were randomised to treatment group (prophylactic LNG-IUS insertion before the commencement of tamoxifen) or control group. Uterine cavity was examined by outpatient hysteroscopy and endometrial biopsy before and at 12 months after commencement of tamoxifen.
Main outcome measures  De novo endometrial pathology at 1 year of tamoxifen.
Results  Women in the treatment group had a much lower incidence of endometrial polyp (1.8 versus 15.5%, P = 0.017) (relative risk: 0.12; 95% CI: 0.02–0.91) at 12 months. There was no significant difference in the incidence of submucosal fibroid between the two groups (1.8 versus 3.4%, P = 1.0). LNG-IUS was retained in 95% women in the treatment group at 1 year.
Conclusion  LNG-IUS reduces the occurrence of de novo endometrial polyp in women treated with tamoxifen for breast cancer.