WHO/FIGO GTN Risk Scoring System
The WHO/FIGO 2000 scoring system for gestational trophoblastic neoplasia (GTN) uses 8 prognostic factors to calculate a total score that determines treatment strategy: scores ≤6 indicate low-risk disease treated with single-agent chemotherapy, while scores ≥7 indicate high-risk disease requiring multi-agent chemotherapy. 1
How the Score is Calculated
The system assigns points (0,1,2, or 4) across eight prognostic factors, which are then summed to produce a total score 1:
The Eight Scoring Factors:
1. Age:
- <40 years = 0 points
- ≥40 years = 1 point
2. Antecedent Pregnancy:
- Mole = 0 points
- Abortion (including miscarriage) = 1 point
- Term birth = 2 points
3. Interval from end of pregnancy to treatment (months):
- <4 months = 0 points
- 4 to <7 months = 1 point
- 7 to <13 months = 2 points
- ≥13 months = 4 points
4. Pretreatment serum hCG (IU/L):
- <10³ = 0 points
- 10³ to <10⁴ = 1 point
- 10⁴ to <10⁵ = 2 points
- ≥10⁵ = 4 points
5. Largest tumor size, including uterus (cm):
- <3 cm = 0 points
- 3 to <5 cm = 1 point
- ≥5 cm = 2 points
6. Site of metastases:
- Lung = 0 points
- Spleen, kidney = 1 point
- Gastrointestinal tract = 2 points
- Liver, brain = 4 points
7. Number of metastases:
- 0 = 0 points
- 1-4 = 1 point
- 5-8 = 2 points
8 = 4 points
8. Previous failed chemotherapy:
- None = 0 points
- Single drug = 2 points
- ≥2 drugs = 4 points
Clinical Application
Risk stratification based on total score:
- Low-risk GTN: Score 0-6 → Single-agent chemotherapy (methotrexate with folinic acid or actinomycin-D) 1, 2
- High-risk GTN: Score ≥7 → Multi-agent chemotherapy (typically EMA/CO regimen) 1, 2
Critical Caveats
The scoring system has important limitations that clinicians must recognize:
The score 5-6 subgroup is problematic: Patients with FIGO scores of 5-6 show disproportionately high chemoresistance rates (44-48%) to single-agent therapy compared to scores 0-4 (28-34%) 3, 4, 5. This suggests these patients may benefit from more aggressive initial treatment despite being classified as "low-risk."
hCG >100,000 IU/L is a red flag: Patients with pretreatment hCG levels exceeding 100,000 IU/L have 84% resistance rates to single-agent methotrexate/folinic acid, regardless of their total FIGO score 3. These patients warrant consideration for multi-agent therapy or closer monitoring.
Not applicable to PSTT/ETT: The FIGO scoring system should NOT be used for placental site trophoblastic tumor (PSTT) or epithelioid trophoblastic tumor (ETT), as these variants have different biological behavior and chemosensitivity 2. These require staging only, with treatment decisions based on stage and interval from last pregnancy.
Most predictive factors: Recent analyses demonstrate that pretreatment hCG level and interval from antecedent pregnancy are the strongest independent predictors of chemoresistance, carrying more weight than other factors 6, 7. Site and number of metastases also show strong predictive value 7.
Practical Implementation
Before calculating the score, obtain 8:
- Complete history including antecedent pregnancy details
- Physical examination
- Serum hCG measurement (immediately before treatment)
- Pelvic ultrasound with Doppler
- Chest X-ray (if normal, no chest CT needed unless metastases visible)
- If metastases ≥1 cm on chest imaging: add brain MRI and abdominal/pelvic CT or MRI
Treatment should begin within 24 hours of completing staging investigations and hCG measurement 8.
The system remains the global standard despite its limitations, as it provides a standardized framework enabling comparison of outcomes across centers 2, 9, 10. However, clinicians should maintain heightened vigilance for patients with scores of 5-6 or hCG >100,000 IU/L, as these subgroups may require treatment intensification beyond what their "low-risk" classification suggests.