Gestational Trophoblastic Disease Treatment (PDQ®): Treatment - Patient Information [NCI] - General Information About Gestational Trophoblastic Disease
Gestational trophoblastic disease (GTD) is a group of rare diseases in which abnormal trophoblast cells grow inside the uterus after conception.
Gestational trophoblastic disease (GTD) develops inside the uterus from tissue that forms after conception (the joining of sperm and egg). This tissue is made of trophoblast cells and normally surrounds the fertilized egg in the uterus. Trophoblast cells help connect the fertilized egg to the wall of the uterus and form part of the placenta (the organ that passes nutrients from the mother to the fetus).
Sometimes there is a problem with the fertilized egg and trophoblast cells. Instead of a healthy fetus developing, a tumor forms. Until there are signs or symptoms of the tumor, the pregnancy will seem like a normal pregnancy.
Most GTD is benign (not cancer) and does not spread, but some types become malignant (cancer) and spread to nearby tissues or distant parts of the body.
Gestational trophoblastic disease (GTD) is a general term that includes different types of disease:
- Hydatidiform Moles (HM)
- Gestational Trophoblastic Neoplasia (GTN)
- Invasive moles.
- Placental-site trophoblastic tumors (PSTT; very rare).
- Epithelioid trophoblastic tumors (ETT; even more rare).
Hydatidiform mole (HM) is the most common type of GTD.
HMs are slow-growing tumors that look like sacs of fluid. An HM is also called a molar pregnancy. The cause of hydatidiform moles is not known.
HMs may be complete or partial:
- A complete HM forms when sperm fertilizes an egg that does not contain the mother's DNA. The egg has DNA from the father and the cells that were meant to become the placenta are abnormal.
- A partial HM forms when sperm fertilizes a normal egg and there are two sets of DNA from the father in the fertilized egg. Only part of the fetus forms and the cells that were meant to become the placenta are abnormal.
Most hydatidiform moles are benign, but they sometimes become cancer. Having one or more of the following risk factors increases the risk that a hydatidiform mole will become cancer:
- A pregnancy before 20 or after 35 years of age.
- A very high level of beta human chorionic gonadotropin (β-hCG), a hormone made by the body during pregnancy.
- A large tumor in the uterus.
- An ovarian cyst larger than 6 centimeters.
- High blood pressure during pregnancy.
- An overactive thyroid gland (extra thyroid hormone is made).
- Severe nausea and vomiting during pregnancy.
- Trophoblastic cells in the blood, which may block small blood vessels.
- Serious blood clotting problems caused by the HM.
Gestational trophoblastic neoplasia (GTN) is a type of gestational trophoblastic disease (GTD) that is almost always malignant.
Gestational trophoblastic neoplasia (GTN) includes the following:
Invasive moles are made up of trophoblast cells that grow into the muscle layer of the uterus. Invasive moles are more likely to grow and spread than a hydatidiform mole. Rarely, a complete or partial HM may become an invasive mole. Sometimes an invasive mole will disappear without treatment.