Gestational Trophoblastic Neoplasia Basics

Gestational Trophoblastic Neoplasia is a type of Gestational Trophoblastic Disease (GTD).

GTD is a heterogeneous group of interrelated lesions arising from the epithelium of the placenta. GTD arises from the placenta, and therefore all forms of the disease produce human chorionic gonadotrophin (hCG), a hormone produced during pregnancy, first by the embryo and later by the placenta, that aids continued progesterone production. hCG is the hormone that produces positive pregnancy tests.

GTD has several types:

• Molar pregnancy (when a non-viable fertilized egg implants in the uterus)
• Complete mole: a non-invasive tumor that results from fertilization of an empty egg by a sperm. No fetal tissues are present. Can progress to metastatic or persistent disease.
• Incomplete mole: a non-invasive tumor that results from fertilization of a normal egg by 2 sperms. Fetal tissues are present, but it is not a viable fetus.
• Persistent or Invasive GTD: once GTD persists or becomes invasive, it is considered a neoplasia. Once this occurs, it is considered a Gestational Trophoblastic Neoplasia (GTN).

GTN has three distinct subtypes:

• Invasive GTN
• Choriocarcinoma
• Placental site trophoblastic tumors (PSTT)

The incidence of GTD varies throughout the world. The highest incidence of GTD in the world occurs in Asia, while North America has one of the lowest rates. This drastic difference in incident rates is often attributed to dietary factors, such as deficiencies in carotene, vitamin C, and animal fats.

Gestational Trophoblastic Neoplasia Risk Factors

The major risk factors for developing GTD are advanced maternal age and history of previous GTD.

Risk factors:

• Advanced maternal age: this is the highest risk factor for the development of GTD. Women over the age of 35 have a significantly increased risk of GTD; as many as 50% of pregnancies in women greater than age 50 are molar pregnancies.
• History of previous GTD: a ten-fold increase in risk of GTD is observed if a woman has had a prior molar pregnancy (1% vs. 0.1%). That risk increases to 20-25% if a woman has had two or more molar pregnancies.
• Smoking: smoking more than 15 cigarettes per day is associated with an increased risk of GTD.
• History of infertility
• Maternal blood type AB, A, or B

Gestational Trophoblastic Neoplasia Diagnosis

GTD can only be definitively diagnosed after a dilation and curettage. The tissue obtained will be reviewed by a pathologist for definitive diagnosis. Prior to this procedure, patients may undergo blood testing and ultrasound imaging.

Once the diagnosis is made, you will require referral to a gynecologic oncologist for follow-up and treatment options.

Gestational Trophoblastic Neoplasia Treatment

Most molar pregnancies do not require treatment after the dilation and curettage. Complete molar pregnancies have a higher risk of developing into a malignancy, as do molar pregnancies in older women. Secondary treatment consists of chemotherapy. The exact chemotherapy regimen will be determined based on many criteria including:

• Pretreatment hCG level
• Age
• Time from prior pregnancy
• Number and sites of metastasis
• Failure of prior chemotherapy

Women with low-risk GTN may be successfully treated with single agent chemotherapy, most likely in the form of methotrexate or actinomycin-D. High-risk GTN is treated with multi-agent chemotherapy and requires overnight hospitalization during the administration. Women who do not wish to preserve their fertility may be treated with hysterectomy, but in high-risk disease, chemotherapy is still required. The hCG level will usually normalize after a few treatments. Chemotherapy will continue for 2 more cycles once normalization of hCG has occurred.

You will continue to have blood drawn to measures hCG levels each month for one year. Becoming pregnant is not recommended during the follow-up period since this can elevate hCG and make it difficult to determine whether an evelated hCG level is due to pregnancy or recurrence. Oral contraceptives are often used during the follow-up period to ensure infertility. There is no evidence that the use of chemotherapy in treating high risk GTN impacts future pregnancies or is associated with adverse fetal outcomes in subsequent pregnancies.