PET Imaging of Estrogen Receptors for Gynecological Tumors

In the past few decades, PET with F-18-FDG has been used for the diagnosis of gynecological malignancies and is considered to be superior to conventional imaging methods in diagnostic accuracy for detecting metastatic lesions and local recurrence and in evaluating the treatment response. On the other hand, several gynecological tumors, such as endometrial cancer and leiomyoma, and breast cancer are estrogen-dependent, in which estrogen is essential for their development and progression. F-18-FES is an F-18-labeled compound of estradiol, the most bioactive type of estrogen, and F-18-FES PET has been well-established for diagnosis, staging, and posttherapeutic follow-up in patients with estrogen receptor-positive breast cancer. Compared with in vitro assessment of tumor biopsy material, PET imaging has the advantages of being able to measure in vivo tumor behavior, characterize the entire tumor burden, and capture the heterogeneity of the tumor phenotype. In this article, we review the phenotyping of estrogen-related gynecological tumors other than breast cancer using F-18-FES PET and demonstrate the additional value of F-18-FES PET to F-18-FDG PET in their diagnosis and prognostication. Moreover, promising PET tracers other than F-18-FES and F-18-FDG for the evaluation of estrogen-related gynecological tumors are introduced.