Benign lesions include placental site nodule and hydatidiform moles while malignant lesions have[2] four subtypes including invasive mole, gestational choriocarcinoma, placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT).

[3] The choriocarcinoma has 2 significant subtypes including gestational and non-gestational and they are differentiated by their different biological feature and prognosis.

The cause of this disease is unknown but the identification of the tumor based on total beta-human chorionic gonadotropin (β-hCG) in the serum.

[4] Although this group of diseases are highly susceptible to chemotherapy, prognosis depends on the type of GTN and whether the tumor has spread to other areas of the body.

A placenta develops in the uterus during pregnancy and becomes first site of nutrient and gas exchange between mother and fetus.

[18] Recently, in order to provide more comprehension tools of GTN pathogenesis, epigenetic modifications and molecular biology techniques could be applied for proper diagnosis, management, and treatment of such neoplasia.

[19] Although chemotherapy and hysterectomy are currently used in a clinical setting, the use of diverse treatments including anti-body and gene therapy also being attempted to cure GTN.

In addition, gene delivery tools using genetically engineered neural stem cells are presently being examined for the treatment of GTN and previous studies have indicated a significant inhibitory effect on tumor growth.