Post-molar gestational trophoblastic neoplasia — structured oral station (12 minutes)

Opening prompt — "Tell me the diagnosis and your immediate plan."

Model response — say it in this order: ^[1][4]

• "Her four hCG values over three weeks are all within 10 per cent of each other — that is the FIGO hCG-plateau criterion, so this is post-molar gestational trophoblastic neoplasia."^[4]
• "Before any treatment I would register her with the Queensland Trophoblast Centre, exclude a phantom hCG with a urine test (hers is negative, so the serum hCG is real), and exclude a new pregnancy with ultrasound — then stage and score her."^[2][4]

Examiner is listening for: the correct FIGO criterion applied to her numbers, phantom hCG exclusion, and registration with the trophoblast centre before treatment. ^[1]

Probe 1 — "Stage and score her."

• "FIGO 2000 staging: Stage I confined to the uterus; Stage II outside the uterus limited to the genital structures; Stage III lungs with or without genital tract involvement; Stage IV all other metastatic sites." ^[1]
• "The WHO prognostic score uses eight variables — age, antecedent pregnancy, interval, pre-treatment hCG, largest tumour size, site of metastases, number of metastases, prior failed chemotherapy — each scored 0, 1, 2 or 4; a total of 6 or below is low-risk, 7 or above is high-risk, and the stage and score are written together as one figure."^[1]
• "With a plateauing hCG at eight weeks, no metastases on her chest radiograph, and a mole as the antecedent pregnancy, her score is almost certainly 6 or below — low-risk."^[2]

Probe 2 — "What chemotherapy will you give her?"

• "Methotrexate 50 mg intramuscularly on days 1, 3, 5 and 7, with folinic acid 15 mg orally on days 2, 4, 6 and 8 — the 8-day low-dose methotrexate-folinic acid regimen, repeated every two weeks."^[3]
• "I would continue until hCG normalises, then give three consolidation cycles after the first normal hCG to prevent relapse."^[3][4]
• "The McNeish 2002 Charing Cross cohort reported 100 per cent overall survival with this regimen, with about two-thirds normalising on methotrexate alone and a third needing a switch."^[3]

Probe 3 — "Her hCG plateaus again during treatment. What now?"

• "This is methotrexate resistance. Because her hCG is low, I would switch to pulsed actinomycin-D 1.25 mg per square metre intravenously every two weeks."^[4]
• "If her hCG were high or rising on a single agent, I would escalate to multi-agent EMA-CO. The switch rule is: low hCG, switch single agent; high or rising hCG, go to multi-agent."^[4]

Probe 4 — "She is frightened and asks whether she will be cured and whether she can have children."

This is a scored domain, not a courtesy. Demonstrate it out loud: ^[2]

• Move to her eye level, use her name, and brief her plainly: "This is a type of pregnancy tumour that we treat extremely successfully. The overall cure rate is over 95 per cent and your fertility is preserved — most women go on to have normal pregnancies."
• "Treatment is chemotherapy by injection every two weeks, with blood tests each cycle. You need reliable contraception throughout because a new pregnancy would interfere with monitoring."
• "Once your hormone level has been normal for six months, you can try to conceive, and we check the hormone level six weeks after any future pregnancy to be safe."^[2]

Probe 5 — "What if she had presented with brain metastases and a score of 13?"

• "That is ultra-high-risk disease. I would not start full-dose EMA-CO — I would begin with low-dose induction etoposide 100 mg per square metre and cisplatin 20 mg per square metre on days 1 and 2 weekly, because sudden tumour lysis in a large burden causes fatal haemorrhage, acidosis and organ failure."^[5]
• "Then full-dose EMA-CO — etoposide, methotrexate and actinomycin-D alternating weekly with cyclophosphamide and vincristine — with brain radiotherapy as required. Induction cut the early-death rate from 7.2 per cent to 0.7 per cent in the Alifrangis cohort."^[5]