Investigation of the 12-month efficacy and safety of low-dose mifepristone in the treatment of painful adenomyosis

Objective: To study the 12-month effects and possible mechanisms of low-dose mifepristone in the treatment of adenomyosis. Methods: Patients included in this retrospective study had painful adenomyosis and previously received 5 mg mifepristone daily (group A, n = 45) or 5 mg mifepristone daily with a poor-effect levonorgestrel-releasing intrauterine device (group B, n = 13) for 12 months. Uterine size, serum CA125 levels, estradiol levels, Visual Analogue Scale (VAS) score, endometrial thickness, and hemoglobin levels were compared before and after treatment and investigated again at 3 to 6 months after drug withdrawal. Another 8 patients with adenomyosis (group C, n = 8) who underwent surgery for severe dysmenorrhea during the same period were only used as a control group for immunohistochemical research. Endometrial biopsy results and expression of nerve growth factor (NGF), cyclooxygenase-2 (COX-2), and nuclear-associated antigen Ki-67 (Ki-67) in endometrial tissues and adenomyotic lesions were also analyzed. Results: The VAS scores in both experimental groups at all time points during treatment and follow-up were significantly lower (P <0.001) than those before treatment. The uterine size was significantly reduced, and endometrial thickness was distinctly thicker after 12 months of treatment than that before treatment in group A receiving 5 mg/d mifepristone. The immunohistochemical expression of NGF and COX-2 decreased in both eutopic and ectopic endometrium after treatment, whereas that of Ki-67 slightly increased in eutopic endometrium after treatment and rapidly recovered to the baseline value after stopping mifepristone. There were no signs of hyperplasia, atypical hyperplasia, or malignancy in the endometrial biopsies. Conclusions: The results suggested that a daily dose of 5 mg mifepristone for 12 months down-regulated the expression of NGF and COX-2 and was effective in treating painful adenomyosis with few side effects.