Potential Benefits of the LNG-IUS in Women Receiving Adjuvant Tamoxifen

Although tamoxifen raises risk for endometrial abnormalities such as hyperplasia and cancer, a 5-year course is often administered as a component of breast cancer therapy because it lowers recurrence risk. Investigators in Hong Kong conducted a 5-year follow-up study to evaluate the effectiveness of the levonorgestrel-releasing intrauterine system (LNG-IUS) in preventing endometrial pathology in 129 Chinese women with breast cancer who were to receive tamoxifen following postoperative radiotherapy and chemotherapy. Participants were randomized to either have or not have an LNG-IUS placed before beginning tamoxifen. Of these, 94 underwent endometrial sampling at baseline and at 12, 24, 45, and 60 months.

Women in the LNG-IUS group were less likely to have endometrial polyps (hazard ratio, 0.2; 95% confidence interval, 0.1–0.5). No cases of endometrial hyperplasia or cancer were reported. Although power was insufficient, breast cancer recurrence rates and numbers of cancer-related deaths were similar in each group.