In a normal pregnancy, cells grow and surround the fertilized egg, connecting the egg to the wall of the uterus and forming the placenta, an important organ responsible for feeding the fetus during pregnancy. Gestational trophoblastic disease (GTD) is a rare condition that occurs after conception when those cells, called trophoblast cells, change and form a mass in the placenta, preventing the development of a healthy fetus.
Although GTD is usually not cancerous, some tumors may become cancerous and spread. GTD is treatable, especially if it’s caught early.
Gestational trophoblastic disease is usually identified as a hydatidiform mole (a molar pregnancy) or as gestational trophoblastic neoplasia (GTN). Each disease is categorized into various subtypes.
Hydatidiform moles are divided into two subtypes:
Complete molar pregnancy: This occurs when the sperm fertilizes an egg that doesn’t contain the woman’s DNA or a nucleus, causing the tissue to form a mound of abnormal cells instead of a fetus. Complete molar pregnancies are typically slow to grow, and most of the time, they are noncancerous, though they are more likely to become cancerous than partial molar pregnancies.
Partial molar pregnancy: This condition develops when the egg is fertilized by two sperms, resulting in two sets of the male’s DNA. Part of a fetus may form in a partial molar pregnancy, but it cannot fully develop.
Gestational trophoblastic neoplasia (GTN)
GTNs are typically cancerous. The types of GTNs include:
Invasive mole, which is a type of molar pregnancy that has the potential to metastasize. They may grow into the muscle layer of the uterus.
Choriocarcinoma, which is a cancerous tumor that may grow quickly and spread to the muscle layer of the uterus, the blood or organs outside the uterus. Choriocarcinomas make up about 5 percent of all GTDs.
Placental-site trophoblastic tumors (PSTT), which is a rare form of GTN that forms where the placenta meets the uterus. These tumors grow slowly, but they may spread to the muscle layer of the uterus, the blood, the lymph nodes, the pelvis or the lungs.
Epithelioid trophoblastic tumors (ETT), which may spread to the lungs. These tumors are the rarest of all GTNs.
GTD accounts for less than 1 percent of all gynecologic cancers and occurs in about one of every 1,000 pregnancies in the United States, according to the American Society of Clinical Oncology. Molar pregnancies account for about 80 percent of all GTDs, while choriocarcinomas occur in about two to seven out of every 100,000 pregnancies in the United States.
Women with GTD may not experience symptoms, or the symptoms may be mistaken for other pregnancy-related events.
Symptoms that do develop may include:
- Vaginal bleeding
- Abdominal swelling
- Ovarian cysts
- Unexplained weight loss
- Pelvic pain or pressure
Various risk factors associated with a woman’s pregnancy may increase her risk.
- Age: Women who are younger than 20 or older than 35 at the time of conception may have a higher risk of developing GTD. Women who are over the age of 45 at the time they become pregnant may have an even higher risk.
- History of molar pregnancy: Women who have had a previous molar pregnancy or who have a family history of molar pregnancy may have a higher risk of GTD.
- History of miscarriage: Women who have had a miscarriage may have a higher risk of developing GTD.
- Blood type: Women with an A or AB blood type may have a higher risk of GTD.
Several diagnostic tests may help determine whether a woman has GTD, including:
- Pelvic exam
- Beta human chorionic gonadotropin (hCG) test
- Lab tests
- CT scan
Treatment for GTD typically includes surgery and/or chemotherapy. Surgery is usually the first treatment option for molar pregnancies, which account for most cases of GTD.
Common surgical options for GTD include suction dilation and curettage (D&C) and hysterectomy. In a D&C, the doctor removes the tissues from the uterus by suctioning the uterus walls, then scraping them. Commonly used in the case of a molar pregnancy, a D&C helps preserve a woman’s fertility. Side effects may include vaginal bleeding, scarring, cramping, infection and blood clots. In most cases, a D&C is the only surgical treatment a GTD patient needs.
In some cases, though, either to reduce the risk of recurrence or to treat PSTT or ETT, a hysterectomy is performed. In a hysterectomy, the uterus and cervix are typically removed. Women who undergo a hysterectomy are no longer able to get pregnant. Side effects may include vaginal bleeding, infection and pain.
Chemotherapy may be used alone as a treatment, or in combination with surgery. It’s commonly used to treat molar pregnancies.
Our comprehensive team of GTD experts
Dr. Julian Schink, Chief of Gynecologic Oncology at Cancer Treatment Centers of America® (CTCA) and Medical Director of Gynecologic and Medical Oncology at our hospital near Chicago, leads our team of gynecologic oncology experts. This comprehensive team provides surgery and chemotherapy treatments for patients with gynecologic cancers, including gestational trophoblastic disease.
Dr. Schink has co-authored several articles and chapters on the treatment of GTD throughout his career, including a chapter on molar pregnancy and gestational trophoblastic neoplasia in Principles and Practice of Gynecologic Oncology, a leading gynecologic oncology textbook. Since 1994, he has also served as the chairman of the Gynecologic Oncology Group’s Gestational Trophoblastic Disease Subcommittee. In that role, he’s led significant trials that have helped evolve the care of GTD.