Gestational Trophoblastic Disease

Gestational trophoblastic disease at a glance

• Gestational trophoblastic disease (GTD) is a group of diseases in which abnormal growths of tissue or tumors occur in the uterus, specifically in the layer of cells surrounding an embryo called the trophoblast that joins the sperm and the egg.
• Hydatidiform moles are the most common GTD and are mostly noncancerous; four kinds of gestational trophoblastic neoplasia (GTN) exist, most of which are cancerous.
• GTD often involves a tumor forming in the uterus rather than a fetus.
  
• Some symptoms of GTD include vaginal bleeding and discharge, abnormal abdominal swelling and vomiting.
• Surgery is the standard form of treatment and may include a dilation & curettage (removal of tissue in the uterus) procedure or hysterectomy (removal of the uterus).

What is gestational trophoblastic disease?

Gestational trophoblastic disease (GTD) is a collection of abnormal cell growths and tumors within the cells of a woman’s uterus. GTD tumors originate in the trophoblast, the cells surrounding the embryo that develop into a placenta during a pregnancy. Gestational trophoblastic disease may also be called gestational trophoblastic tumors or gestational trophoblastic neoplasia (neoplasia means new growth).

Gestational trophoblastic disease begins in the layer of cells surrounding an embryo called the trophoblast that joins the sperm and the egg. The cells of the trophoblast (“tropho” means nutritious and a “blast” is an early development cell) eventually develop into the placenta, which nourishes the growing fetus during gestation (pregnancy).

The main forms of GTDs

• Hydatidiform mole is the most common type of GTD and is also known as a molar pregnancy. In hydatidliform moles, the egg and sperm have joined but do not form a fetus in the uterus. Instead they form a tumor that looks like a cluster of grapes. There are two types of hydatidliform moles, both can be removed by surgery:
  • Partial hydatidliform moles occur when two sperms fertilize one egg so two sets of the father’s DNA are in the fertilized egg but none from the mother. This results in a partially formed fetus that is not viable.
    
  • Complete hydatidliform moles occur when there is no nucleus or DNA in the fertilized egg. These can be cancerous, but that occurs rarely.
    
• Gestational trophoblastic neoplasia, which are almost always cancerous:
  
  • Invasive mole is a hydatidiform mole that has grown into the uterus muscles and tissues. Sometimes invasive moles disappear naturally, but usually require surgical removal.
    
  • Choriocarcinoma is a malignant form of GTN that forms either from hydatidliform moles, miscarriage or ectopic pregnancy. Choriocarcinomas spread from the muscle layer of the uterus to nearby blood vessels and often beyond, to the brain, lungs, kidneys and vagina.
    
  • Placental-site trophoblastic tumor is a rare form of GTD caused by placental attachment to the lining of the uterus. These tumors may also spread to other parts of the body.
    
  • Epithelioid trophoblastic tumor (ETT) is the rarest of all GTNs and is sometimes confused with cervical cancer. In some cases an ETT, which can be benign or malignant, isn’t diagnosed until several years following a pregnancy.

Causes and symptoms of gestational trophoblastic disease

GTD occurs during a pregnancy, but the specific causes of the abnormal cell growth are not known. GTD originates in the trophoblast cells that surround an embryo. During the early stages of conception, the trophoblast cells form small projections called villi. These eventually grow into the uterine lining and, later in the pregnancy, form the placenta. GTD is diagnosed when there is abnormal cell growth or mutation in these tissues.

Identifiable risk factors that increase chances of GTD include higher maternal age and a previous GTD pregnancy. The majority of GTDs are noncancerous and do not spread to other parts of the body. As a result, most GTDs are usually treated and cured successfully.

Symptoms of gestational trophoblastic disease

GTD is typically diagnosed during a routine pregnancy checkup with blood tests or ultrasound. Physical symptoms usually do not present until later on or even after birth.

When GTD symptoms do present, they may include:

• Vaginal bleeding or brown watery discharge — this is especially common with hydatidiform moles
• More severe and regular vomiting than typically expected, a doctor may order a GTD test
• Abdominal swelling greater than is typically expected may be an indicator of a GTD
• Ovarian cysts, which sometimes result from a GTD

Treating gestational trophoblastic disease

Treatment for GTD varies according to type and stage of the associated tumor. Treatment is mandatory to continue a healthy pregnancy, or to have another healthy pregnancy after pregnancy failure due to GTD. The standard treatment includes some form of surgery.

A dilation and curettage (D&C) is a surgical procedure that removes portions of the uterus lining and all abnormal cells. During a D&C, the surgeon dilates the cervix and removes the cells with a vacuum-like device. The surgeon then scrapes any remaining material with a curette, a spoon-like instrument.

A hysterectomy, the removal of the uterus and sometimes the cervix, may also be recommended as a surgical treatment. This option does not allow the woman to have any future children.

Once treated, women with GTD will continue to have levels of the human chorionic gonadotropin (HCG) hormone monitored for six months to one year to ensure no remaining GTD tissue.