# Gestational Trophoblastic Neoplasia

> NEET-PG OBG notes on gestational trophoblastic neoplasia covering post-molar hCG criteria, choriocarcinoma, FIGO risk scoring and chemotherapy.

- Canonical URL: https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/gestational-trophoblastic-neoplasia
- Exam / course: NEET-PG · Subject: Obstetrics and Gynaecology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Gestational Trophoblastic Neoplasia", PrepElephant, https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/gestational-trophoblastic-neoplasia

## Direct answer

Gestational trophoblastic neoplasia is persistent proliferating trophoblast after a molar pregnancy (and occasionally after abortion or term delivery) that invades tissue, metastasises and secretes human chorionic gonadotropin. It comprises invasive mole, choriocarcinoma and the rarer placental site trophoblastic tumour. The FIGO diagnosis rests on a plateau or rise of hCG after molar evacuation, persistence beyond six months, histological choriocarcinoma or the presence of metastases. A WHO-modified FIGO risk score stratifies treatment: score below 7 (low risk) receives single-agent methotrexate or actinomycin-D with cure rates near 100 per cent, while score 7 or more (high risk) needs multi-agent EMACO chemotherapy.

## What you must remember

- Post-molar diagnostic criteria (FIGO): four hCG values plateauing (within 10 per cent) over three consecutive weeks (days 1, 7, 14, 21); a rise of 10 per cent or more over three values across two weeks; hCG still detectable six months after evacuation; histological choriocarcinoma; or metastases with rising hCG.
- Histological spectrum: invasive mole — hydropic villi invading the myometrium, always follows a mole; choriocarcinoma — anaplastic cyto- and syncytiotrophoblast with haemorrhage and necrosis but no villi, arising after a mole in about half of cases and after abortion or term pregnancy otherwise; placental site trophoblastic tumour — intermediate trophoblast, low hCG, human placental lactogen-positive.
- Metastatic spread: haematogenous — lung commonest, then vagina, brain and liver; brain or liver involvement or very high hCG weighs heavily in the risk score.
- Staging and scoring: FIGO anatomic stage I (confined to uterus) to IV (metastases with risk factors), combined with the modified WHO score based on age, antecedent pregnancy interval, pre-treatment hCG, tumour size and site, number of metastases and prior failed chemotherapy.
- Low-risk treatment: single-agent methotrexate (for example 0.4 mg/kg intramuscularly daily for five days every two weeks) or actinomycin-D; treatment continues until hCG normalises plus consolidation cycles.
- High-risk treatment: EMACO — etoposide, methotrexate, actinomycin-D, cyclophosphamide and vincristine (Oncovin) — with central nervous system-directed therapy (radiation or intrathecal/intravenous strategies) for brain metastases; hysterectomy is adjunctive in selected women.
- Follow-up: hCG monitoring during and after treatment with prolonged contraception; salvage surgery for chemotherapy-resistant disease; placental site trophoblastic tumour is relatively chemoresistant and primarily surgical.

## Common confusion

Choriocarcinoma and invasive mole are interchanged: villi are present in invasive mole and absent in choriocarcinoma, and choriocarcinoma can follow any pregnancy, not only a mole. The second error is treating an early follow-up hCG plateau as laboratory noise; the FIGO plateau definition (values within 10 per cent across the specified sequence) converts a laboratory trend into a treatment trigger.

## Exam-focused takeaway

Stems quote an hCG series after evacuation and ask whether neoplasia is diagnosed; others give histology (villi versus no villi), a metastasis pattern (lung, vagina, brain) or a risk score and ask for the regimen — methotrexate or actinomycin-D for low risk, EMACO for high risk. The near-100 per cent cure of low-risk disease with fertility retained is a favourite counselling point.

## Frequently asked questions

### When is post-molar GTN diagnosed?

On hCG plateau within 10 per cent across three weekly values, a 10 per cent or greater rise across two weeks, persistence beyond six months, choriocarcinoma on histology, or metastases.

### How do invasive mole and choriocarcinoma differ histologically?

Invasive mole retains hydropic chorionic villi within the myometrium; choriocarcinoma shows malignant trophoblast with haemorrhage and necrosis and no villi.

### Which chemotherapy is used for low-risk disease?

Single-agent methotrexate or actinomycin-D with consolidation after hCG normalisation; cure rates approach 100 per cent.

### What is the high-risk regimen?

EMACO — etoposide, methotrexate, actinomycin-D, cyclophosphamide and vincristine — plus central nervous system-directed measures for brain metastases.

### Where does choriocarcinoma metastasise first?

The lungs are reached first, then the vagina, brain and liver.