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Gestational Trophoblastic Neoplasia

This information should not be used for self-diagnosis or in place of a qualified physician's care.

Revised Nov 2020

The basics
  • Guidelines for treating this disease have been developed by the Gynecology Tumour Group.
  • For health professional information on treating this cancer, please see our Cancer Management Guidelines.
  • These terms describe the range of the disease including: benign hydatidiform mole (also known as molar pregnancy), invasive mole, choriocarcinoma, and placental site tumour.
  • The term 'gestational' refers to pregnancy. The trophoblast is a layer of cells that form the placenta. The placenta is the organ that nourishes the growing baby within the uterus.
  • Gestational trophoblastic tumours occur inside the uterus, in the cells that would normally develop into the placenta during pregnancy.
  • After conception, when an egg is fertilized by a sperm, trophoblast cells help form the placenta and help the embryo to attach to the uterus. Abnormalities may develop in the layer of cells surrounding the embryo (trophoblast).
  • In the early stages of this disease, the changes that occur in a person's body may make it seem like a normal pregnancy. Even a blood test would detect pregnancy due to the high amount of the pregnancy hormone, human chorionic gonadotropin (HCG) in the body.
  • If a person has had one or more molar pregnancies it is still possible to have normal full-term pregnancies.
What causes it and who gets it?
Listed below are some of the known risk factors for this cancer. Not all of the risk factors below may cause this cancer and not all women have risk factors but they may be contributing factors.

  • Gestational trophoblastic tumours occur in people who are in their child-bearing years.
  • People are more at risk if they are under 20 or over 40 years old when they become pregnant. [See note, Statistics]
  • If a person has had a previous hydatidiform mole (molar pregnancy), it may increase their risk of developing a gestational trophoblastic tumour.
  • A person who has had a previous hydatidiform mole may also have an increased risk of having another hydatidiform mole.
  • Statistics - These cancers are very rare so incidence rates have been combined with other unspecified cancers
    NOTE:  Available statistics do not have information about the inclusion of transgender and gender diverse participants. Unless specified, it is unknown how these statistics apply to transgender and gender diverse people.  Patients are advised to speak with their primary care provider or specialists about their individual considerations and recommendations.
Can I help to prevent it?

This is a rare condition and specific prevention strategies are unknown.

Screening for this cancer

No effective screening program exists for this cancer yet.

Signs and Symptoms
  • Your period is delayed
  • You feel pregnant
  • Abdominal swelling
  • The size of the uterus is larger or smaller than expected for the time in pregnancy.
  • High levels of a pregnancy hormone called human chorionic gonadotropin (HCG) in the blood.
  • Nausea
  • Excessive vomiting
  • Pre-eclampsia (sudden increase in blood pressure during pregnancy)
  • Overactive thyroid gland
  • Vaginal bleeding that may suggest a miscarriage
  • Grape-like tissue passing from vagina along with blood
Diagnosis & staging


These are tests that may be used to diagnose this type of cancer.

  • Pelvic examination
  • Blood test to measure the amount of the pregnancy hormone, human chorionic gonadotropin (HCG) in the blood.
  • Ultrasound
  • Chest x-ray
  • Because of the extensive use of ultrasound during pregnancy, diagnosis usually comes early in gestation.
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests section.

Types and Stages


Hydatidiform mole
  • A hydatidiform mole is also called a molar pregnancy.
  • It is usually diagnosed within the first 12 weeks of pregnancy.
  • A hydatidiform mole can be classified either as complete or partial.
    • In a normal conception, half of the baby's genes come from the male sperm and half from the female egg.
    • In a complete hydatidiform mole, an empty egg is fertilized by a sperm and the complete genetic content is only from the sperm. A baby does not develop and a mass that looks like grape-like tissue fills the uterus.
    • In a partial hydatidiform mole, one egg is fertilized by two sperm and there are three sets of chromosomes instead of the normal two sets. A baby develops, but dies within a few weeks of pregnancy.
  • A hydatidiform mole is benign rather than cancerous but it could develop into cancer.
  • There is a higher chance of a complete hydatidiform mole developing into an invasive mole or choriocarcinoma than the partial type of hydatidiform mole.
Invasive mole
  • An invasive mole occurs when hydatidiform mole tissue that remains in the uterus grows into the muscle layer (myometrium).
  • A tumour develops from the tissue that started as a hydatidiform mole, or tissue that is still in the uterus after treatment for hydatidiform mole. It can also develop from tissue that remains in the uterus after an abortion or following the delivery of a baby.
  • Choriocarcinoma can spread to other parts of the body.
Placental-site trophoblastic tumour
  • A placental-site trophoblastic tumour is a very rare type of cancer.
  • It starts in the place where the placenta was attached to the muscle of the uterus.
Stages Staging describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.

T describes the site and size of the main tumour (primary)

N describes involvement of lymph nodes

M relates to whether the cancer has spread (presence or absence of distant metastases) 

Stage I
The disease is confined to the uterus 

Stage II
The disease has spread outside of the uterus to other genital areas 

Stage III
The disease has spread to the lungs 

Stage IV
The disease has spread to other parts of the body


Cancer therapies can be highly individualized – your treatment may differ from what is described below.

Gestational trophoblastic tumours are very curable, especially if found early.

  • The treatment for hydatidiform mole is to remove the contents of the uterus using the dilation and curettage (D & C) method. In this procedure, the cervix is made larger (dilated) so that the contents of the uterus can be removed with a small vacuum-like device. A spoon shaped instrument removes any tissue that remains from the walls of the uterus.
    • Following this procedure, the level of human chorionic gonadotropin (HCG) will be monitored frequently through blood tests.
  • If a placental-site trophoblastic tumour or an invasive molar pregnancy are confined to the uterus, they can be treated with a hysterectomy (an operation to take out the uterus). This option is for patients who do not wish to have any more children.
  • Invasive moles and choriocarcinoma can be treated with chemotherapy.
  • Low risk patients can be cured by single agent or combination chemotherapy (uses several different agents simultaneously).
  • High risk patients with a high HCG level and metastasis to the brain, liver or more than one organ site are treated with intensive, multi-agent chemotherapy.
Follow-up after Treatment
  • Guidelines for follow-up after treatment are covered on our website.
  • You will be returned to the care of your family doctor or your specialist for regular follow-up, including monitoring of HCG. If you do not have a family physician, please discuss this with your BC Cancer oncologist or nurse.
  • Follow-up testing is based on your type of cancer and your individual circumstances.
  • Life after Cancer focuses on the issues that cancer survivors can face.
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