New therapeutic approaches for the fertility-sparing treatment of endometrial cancer.

This review seeks to describe new fertility-sparing endometrial cancer (EC) treatment strategies that take into consideration the medical and general health background of patients. We particularly focus on the application of metformin, which is a biguanide widely prescribed for treatment of type 2 diabetes mellitus. Fertility-sparing treatment using progestin is considered a standard treatment option for patients with atypical endometrial hyperplasia (AEH) and EC who desire to conceive. A previous meta-analysis of fertility-sparing treatments revealed a high remission rate; however, high rates of relapse persisted. Most young patients with AEH and EC who are subjected to fertility-sparing treatment have a background of obesity, insulin resistance and abnormal glucose tolerance complicated with polycystic ovary syndrome. Recently, metformin has been attracting more attention in the field of cancer research. Several in vitro and in vivo reports regarding the efficacy of metformin in EC management have accumulated. Thus far, the efficacy of combining metformin with progestin has been revealed in a single phase II study of medroxyprogesterone acetate in combination with metformin as a fertility-sparing treatment for patients with AEH or EC. In addition to improving the metabolic profile of patients with EC having metabolic disorders, metformin supplementation may improve the long-term oncological outcome of these patients. To date, many clinical trials employing progestin and metformin as a fertility-sparing treatment of AEH and EC are ongoing. In the near future, it is expected that the clinical advantage of metformin progestin combination therapy will be clarified.