Gestational trophoblastic neoplasia — structured SAQ (15 marks)

(a) Diagnosis and immediate next steps (3 marks)

One mark for the diagnosis, two for the criteria and next steps. ^[1][3]

• Diagnosis: post-molar gestational trophoblastic neoplasia, because the hCG has plateaued across four values over about four weeks.^[1][3]
• Criteria met: the FIGO hCG criteria for post-molar GTN — a sustained plateau (no significant fall; operationally a fall of less than 10%) — also includes a sustained rise (over 10%), persistence beyond six months, histological choriocarcinoma, or metastases.^[1][3]
• Next steps: confirm the hCG is real with a urine test (exclude phantom hCG) and exclude a new pregnancy with ultrasound; register with the regional trophoblast centre; stage and score; examine for metastases; then risk-stratify treatment.^[3]

(b) FIGO 2000 anatomic staging (3 marks)

Reproduce verbatim — one mark roughly per stage band, all four for full marks. ^[1][2]

• Stage I: disease confined to the uterine corpus.
• Stage II: GTN extends outside the uterus but is limited to the genital tract structures (adnexa, vagina, broad ligament).
• Stage III: GTN extends to the lungs, with or without genital tract involvement.
• Stage IV: all other metastatic sites.

The stage and the WHO score are written together as a single figure (for example, Stage I:3).^[2]

(c) The WHO eight-variable score and the cut-off (5 marks)

Up to one mark each for the variables named and the cut-off and the Charing Cross convention. ^[2][3]

The eight variables, each scored 0, 1, 2 or 4: ^[1]

• Age
• Antecedent pregnancy (mole, abortion, term)
• Interval (months) from index pregnancy
• Pre-treatment serum hCG
• Largest tumour size, including uterus
• Site of metastases (lung; spleen or kidney; gastrointestinal; liver or brain)
• Number of metastases identified
• Previous failed chemotherapy (none; single drug; two or more drugs)

Cut-off: a total score of 6 or below is low-risk (single-agent chemotherapy); 7 or above is high-risk (multi-agent EMA-CO).^[3] A 2026 FIGO revision exists (Ngan et al, Int J Gynaecol Obstet 2026) — consult the current score table at the station.^[7] Charing Cross convention: patients scoring 0 to 8 are low-risk (methotrexate-folinic acid), over 8 high-risk (EMA-CO).^[4]

(d) First-line chemotherapy and expected outcome (4 marks)

Two marks for the regimen with dose and schedule, one for consolidation, one for the outcome. ^[4][5]

• The Charing Cross 8-day methotrexate-folinic acid regimen: methotrexate 50 mg intramuscularly on days 1, 3, 5 and 7, with folinic acid (leucovorin) rescue on days 2, 4, 6 and 8, repeated every two weeks.^[4][5]
• Continue until hCG normalises, then give consolidation cycles.^[3]
• The alternative is pulsed actinomycin-D 1.25 mg per square metre intravenously every two weeks, used first-line where methotrexate is contraindicated or second-line on resistance.^[5]
• Expected outcome: the McNeish 2002 Charing Cross cohort of 485 women reported 100% overall survival; hCG normalised with methotrexate alone in about 67%, with about a third needing a change of single agent without survival compromise.^[4]