Persistent elevation of serum hCG levels after a non molar pregnancy (i.e., normal pregnancy [term pregnancy], or preterm pregnancy, or ectopic pregnancy [pregnancy taking place in the wrong place, usually in the fallopian tube], or abortion) always indicate persistent GTD (very frequently due to choriocarcinoma or placental site trophoblastic tumour), but this is not common, because treatment mostly is successful. In rare cases, a previous GTD may be reactivated after a subsequent pregnancy, even after several years. Therefore, the hCG tests should be performed also after any subsequent pregnancy in all women who had had a previous GTD (6 and 10 weeks after the end of any subsequent pregnancy). Prognosis
Women with a hydatidiform mole have an excellent prognosis. Women with a malignant form of GTD usually have a very good prognosis.Choriocarcinoma, for example, is an uncommon, yet almost always curable cancer. Although choriocarcinoma is a highly malignant tumour and a life-threatening disease, it is very sensitive to chemotherapy. Virtually all women with non-metastatic disease are cured and retain their fertility; the prognosis is also very good for those with metastatic (spreading) cancer, in the early stages, but fertility may be lost. Hysterectomy (surgical removal of the uterus) can also be offered to patients > 40 years of age or those for whom sterilisation is not an obstacle. Only a few women with GTD have a poor prognosis, e.g. some forms of stage IV GTN. The FIGO staging system is used.
Gestational trophoblastic disease (GTD) is a term used for a group of pregnancy-related tumours. These tumours are rare, and they appear when cells in the womb start to proliferate uncontrollably. The cells that form gestational trophoblastic tumours are called trophoblasts and come from tissue that grows to form the placenta during pregnancy. There are several different types of GTD. A hydatidiform mole also known as a molar pregnancy, is the most common and is usually benign. Sometimes it may develop into an invasive mole, or, more rarely into a choriocarcinoma. A choriocarcinoma is likely to spread quickly, but is very sensitive to chemotherapy, and has a very good prognosis. Trophoblasts are of particular interest to cell biologists because, like cancer, they can invade tissue (the uterus), but unlike cancer, they usually  "know" when to stop.GTD can simulate pregnancy, because the uterus may contain fetal tissue, albeit abnormal. This tissue may grow at the same rate as a normal pregnancy, and produces chorionic gonadotropin, a hormone which is measured to monitor fetal well-being.While GTD overwhelmingly affects women of child-bearing age, it may rarely occur in postmenopausal women. Types
GTD is the common name for five closely related tumours (one benign tumour, and four malignant tumours):
The benign tumour
Hydatidiform moleHere, first a fertilised egg implants into the uterus, but some cells around the fetus (the chorionic villi) do not develop properly. The pregnancy is not viable, and the normal pregnancy process turns into a benign tumour.