A randomised controlled trial of prophylactic levonorgestrel intrauterine system in tamoxifen-treated women. Endometrial protection from tamoxifen-stimulated changes by a levonorgestrel-releasing intrauterine system: a randomised controlled trial.
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.
                Randomised controlled trial.
                A tertiary teaching hospital.
                One hundred and thirteen women (66 premenopausal/47 postmenopausal) who required adjuvant tamoxifen for breast cancer after the completion of postoperative radiotherapy and chemotherapy.
                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.
                De novo endometrial pathology at 1 year of tamoxifen.
                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.
                LNG-IUS reduces the occurrence of de novo endometrial polyp in women treated with tamoxifen for breast cancer. Tamoxifen is currently the most commonly used adjuvant treatment for breast cancer, however, it frequently causes episodes of unscheduled uterine bleeding, which could be associated with proliferative changes of the endometrium, or even endometrial cancer. We aimed to assess whether a levonorgestrel intrauterine system could modulate the uterine responses to tamoxifen. We also aimed to assess women's tolerance of the screening procedures, the insertion, removal, and potential side-effects of the device.
                We did a randomised controlled trial, in which postmenopausal women who had had at least 1 year of adjuvant tamoxifen treatment and who were undergoing regular follow-up for breast cancer were randomly assigned to either endometrial surveillance alone, or endometrial surveillance before and after insertion of the levonorgestrel intrauterine system for 12 months. We assessed tolerance of the surveillance procedures and the device with visual analogue scales.
                Baseline assessment showed only benign uterine changes in all women (n=122). Hysteroscopic assessment indicated a uniform decidual response (confirmed histologically in 40 of 41 cases) in all women fitted with the intrauterine system; there were no new polyps in these women and 13% had fewer fibroids than in controls. Both screening procedures and device were well tolerated. There was an excess of bleeding in the women fitted with intrauterine systems but this resolved to a baseline similar to those receiving surveillance only.
                The levonorgestrel-releasing intrauterine system had a protective action against the uterine effects of tamoxifen. The effectiveness of this device in preventing uterine changes in the endometrium needs to be assessed in the context of decreasing the need for repeated investigations of postmenopausal bleeding in women taking tamoxifen.
The Mirena LNG-IUS appears to prevent the development of benign endometrial polyps in breast cancer patients taking tamoxifen, over a one-year period. There is no clear evidence from the available randomised controlled trials that LNG-IUS prevents endometrial hyperplasia or adenocarcinoma in these patients. Larger studies are necessary to assess the effects of LNG-IUS in preventing endometrial hyperplasia and endometrial cancer, and to determine whether LNG-IUS might have an impact on the risk of breast cancer recurrence.