Gestational Trophoblastic Disease

AbstractGestational trophoblastic disease (GTD) is a disease of the proliferative trophoblastic allografts and includes partial mole (PM), complete hydatidiform mole (CM), invasive mole, metastatic mole, choriocarcinoma (CC), and placental site trophoblastic tumor (PSTT). While CC and PSTT are definitely neoplastic, the various types of molar pregnancies are basically benign, but with a potential to behave like a malignant disease that requires chemotherapy. This potential malignant behavior is identified by the failure of regression of the human chorionic gonadotrophin (hCG) in the absence of a normal pregnancy and is termed gestational trophoblastic tumor (GTT) or gestational persistent trophoblastic disease (GPTD). The criteria for the diagnosis of postmolar GTT varies among different centers in the world. Basically, if the hCG level fails to fall satisfactory over 3–4 weeks, or when there is a rise in the hCG level over 2–3 weeks, GTT is diagnosed and further investigations should be done to assess the extent of the disease. The risk or predictive factors of PTD following mole will be discussed in the first major section below.In GTT, unlike other solid malignancies, metastasis does not always mean poor prognosis. If the metastatic lesion is a mole rather than CC, the prognosis is much better. However, histological confirmation is uncommon because most cases of GTT are treated with chemotherapy. Thus, other prognostic factors in addition to metastasis have to be taken into consideration in assessing the prognosis of a GTT. The prognostic factors of GTT are be discussed in the second major section below. PSTT arises from the intermediate trophoblasts and behaves quite differently from that of GTT and will be discussed separately in the final major section below.