Interactive EORTC NMIBC Risk Calculator
Estimate 1-year and 5-year recurrence/progression risk for non-muscle-invasive bladder cancer (NMIBC) using EORTC risk tables.
What is the EORTC bladder cancer calculator?
The EORTC bladder cancer calculator is a clinical risk tool designed for patients with non-muscle-invasive bladder cancer (NMIBC). It estimates the chance of:
- Recurrence (cancer coming back in the bladder), and
- Progression (disease becoming more aggressive, such as stage advancement).
The model uses six routine pathology and clinical factors to produce two scores: a recurrence score and a progression score. Those scores are then mapped to estimated 1-year and 5-year probabilities.
Variables used in the score
The calculator combines these six features from the original EORTC risk system:
- Number of tumors
- Tumor size (<3 cm vs ≥3 cm)
- Prior recurrence rate
- T category (Ta vs T1)
- Concomitant CIS
- Tumor grade (WHO 1973: G1, G2, G3)
Scoring framework (summary)
| Factor | Recurrence points | Progression points |
|---|---|---|
| Number of tumors | Single: 0, 2-7: 3, ≥8: 6 | Single: 0, 2-7: 3, ≥8: 3 |
| Largest tumor diameter | <3 cm: 0, ≥3 cm: 3 | <3 cm: 0, ≥3 cm: 3 |
| Prior recurrence rate | Primary: 0, ≤1/yr: 2, >1/yr: 4 | Primary: 0, ≤1/yr: 2, >1/yr: 2 |
| T category | Ta: 0, T1: 1 | Ta: 0, T1: 4 |
| Concomitant CIS | No: 0, Yes: 1 | No: 0, Yes: 6 |
| Grade (WHO 1973) | G1: 0, G2: 1, G3: 2 | G1: 0, G2: 0, G3: 5 |
How to interpret your results
After calculation, the tool reports:
- Your total recurrence score and risk group
- Your total progression score and risk group
- Estimated probability at 1 year and 5 years
These probabilities are population-level estimates from historical cohorts. They are most useful for shared decision-making and follow-up planning, not for predicting exactly what will happen to one individual patient.
Important limitations
1) Treatment era and BCG exposure
The original EORTC cohorts included many patients not treated with current BCG maintenance strategies. In modern BCG-treated populations, recurrence and progression may differ from the original tables.
2) Pathology and grading updates
This tool uses WHO 1973 grades (G1/G2/G3), which are still commonly mapped in research, but many centers now use WHO 2004/2016 terminology (low grade/high grade). Ask your urology team how your current pathology translates.
3) Not for all bladder cancer scenarios
The EORTC model is intended for NMIBC. It should not be used as a standalone decision tool for muscle-invasive disease, metastatic disease, or special histologic variants without expert input.
Clinical use: where this calculator helps most
- Framing surveillance intensity (cystoscopy schedules)
- Discussing intravesical treatment strategy
- Risk communication between clinician and patient
- Documenting baseline recurrence/progression risk at diagnosis
Bottom line
The EORTC bladder cancer calculator remains a practical, quick bedside estimate for NMIBC risk stratification. Use it as a structured conversation tool alongside pathology review, guideline recommendations, and individualized specialist care.