What is invasive mole and choriocarcinoma?

Invasive mole and choriocarcinoma are both types of gestational trophoblastic disease. 

Very rarely, abnormal cells or tumours can grow from the tissue that forms in the womb during pregnancy. This is called gestational trophoblastic disease (GTD). GTD can be cancerous or non cancerous (benign). Invasive mole and choriocarcinoma are both cancerous types of GTD.

Invasive mole and choriocarcinoma are most commonly found in the womb. But they can spread to other areas of the body and might cause symptoms there.

Invasive mole

A molar pregnancy happens when the fertilisation of the egg by the sperm goes wrong. This leads to the growth of abnormal cells or clusters of water filled sacs inside the womb. Only about 1 in every 590 pregnancies in the UK is a molar pregnancy.

Usually any molar cells left after treatment will die off by themselves. But sometimes they will keep growing and become cancerous. This is called an invasive mole or persistent trophoblastic disease (PTD). This occurs in about 1 in 12 women (8%) after molar pregnancy treatment.

Even a very small amount of molar tissue anywhere in the body can grow and cause problems. Like other cancers, an invasive mole can spread to other parts of the body. But it has a cure rate of nearly 100%.

The treatment for an invasive mole is usually chemotherapy.


A choriocarcinoma is a cancer that happens when cells that were part of a normal pregnancy or a molar pregnancy become cancerous. Chorio refers to the word chorion, which is the outer covering of the growing baby (foetus). Carcinoma means cancer in the epithelial cells which cover or line a body organ.

Choriocarcinoma is more common after a molar pregnancy. It can also happen after a full term pregnancy, miscarriage, ectopic pregnancy or abortion.

Choriocarcinoma only happens in about 1 in every 50,000 pregnancies. 

A choriocarcinoma can develop some months or even years after pregnancy. It can be difficult to diagnose because it is so rare. It can grow quickly and might cause symptoms within a short period of time. A choriocarcinoma can spread to other parts of the body, but is usually cured by chemotherapy treatment or surgery.

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