The cause of choriocarcinoma is uncertain. It can arise from a normal pregnancy, a miscarriage, a tubal pregnancy or from either type of mole. How It Spreads Hydatidiform moles generally stay confined to the uterus. When it begins to invade the wall of the uterus, it is called an invasive mole. An invasive mole can penetrate the full thickness of the uterine wall and rupture, resulting in severe internal or vaginal bleeding.
Invasive moles can also spread to other organs, most commonly to the vagina and the lung.
This may be confusing since women with proven invasive moles who have metastases may also have choriocarcinoma. Although an invasive mole is more aggressive locally than a non-invasive mole, it is no more likely to be complicated by a choriocarcinoma. Risk Factors Gestational trophoblastic disease occurs only in women of reproductive age. An invasive mole develops in 10 to 20 percent of all complete moles and 5 to 10 percent of all partial moles. Choriocarcinoma develops in three percent of complete moles but rarely in partial moles.