17 - Gestational trophoblastic neoplasia

Summary

Introduction

Gestational trophoblastic neoplasia (GTN) comprises a spectrum of related conditions, all of which are characterised by low incidence and high cure rates. The diagnoses range from the generally benign conditions of partial hydatidiform molar pregnancy (PHM) and complete hydatidiform molar pregnancies (CHM) through to the aggressive malignancies of choriocarcinoma and placental site trophoblastic tumours (PSTT). The optimal care of women with these rare conditions relies on good team-working between obstetricians, gynaecologists, pathologists, oncologists and a well-organised post-molar pregnancy follow-up team.

Molar pregnancies make up the majority of cases of GTN and approximately 10% of these women will require additional therapy following their uterine evacuation. Those women who develop malignancy after a molar pregnancy should rarely prove difficult to treat as, in areas with well-organised care, overall cure rates approaching 100% are reported. The GTN patients with choriocarcinoma or PSTT occurring after a non-molar pregnancy can present with a wide variety of symptoms, which may lead to treatment delays while the diagnosis is made. Fortunately, the majority of these women should also have the expectation of curative treatment, although this is likely to be more complex and toxic.

Classification and genetic origins of GTN

Premalignant forms of GTN

Partial and complete molar pregnancies

The various forms of GTN develop from the trophoblast cells of the conception via two separate genetic pathways.