What are the key statistics about gestational trophoblastic disease?

Hydatidiform moles occur in about 1 pregnancy out of 1,000 in the United States and Europe. In very rare cases (less than 1%), a normal fetus can develop along with the hydatidiform mole.

In about 15% of cases, a hydatidiform mole will progress to become an invasive mole. Overall, invasive moles occur at an estimated rate of 1 pregnancy in 15,000.

Choriocarcinoma, a malignant form of gestational trophoblastic disease (GTD), is even less common, affecting around 2 to 7 of every 100,000 pregnancies in the United States. Like other forms of GTD, choriocarcinoma is more common in many Asian and African countries.

About 2% to 4% of hydatidiform moles progress to become choriocarcinoma. But only half (50%) of all gestational choriocarcinomas start off as molar pregnancies. About one-quarter (25%) of all choriocarcinomas develop in women who have a miscarriage (spontaneous abortion), intentional abortion, or tubal pregnancy (the fetus develops in the fallopian tube, rather than in the uterus). Another quarter (25%) develop after normal pregnancy and delivery.

Overall, gestational trophoblastic tumors account for less than 1% of female reproductive system cancers.

Cure rates depend on the type of GTD and its stage, as described in the section “Treatment of gestational trophoblastic disease by type and stage.”