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.

Methods: Randomised controlled trial. Methods: A tertiary teaching hospital. Methods: 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. Methods: 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.

Conclusions: LNG-IUS reduces the occurrence of de novo endometrial polyp in women treated with tamoxifen for breast cancer.