EORTC Bladder Cancer Recurrence and Progression Risk Calculator
This calculator implements the 2006 EORTC risk-scoring system for non-muscle-invasive bladder cancer (NMIBC). Enter the six clinical and pathological factors from the TURBT report to get separate recurrence and progression scores, along with 1-year and 5-year probability estimates and risk category classifications. The model was derived from nearly 2,600 patients across seven EORTC clinical trials and is recommended by major urology guidelines as a standard decision-support tool.
What is the EORTC bladder cancer risk calculator?
The European Organisation for Research and Treatment of Cancer (EORTC) developed this scoring system in 2006 to help clinicians estimate the likelihood that non-muscle-invasive bladder cancer (NMIBC) will recur after complete transurethral resection of bladder tumors (TURBT), and the separate likelihood that it will progress to muscle-invasive disease. The model was built from individual patient data pooled across seven randomized EORTC clinical trials involving 2,596 patients and validated in independent cohorts. Six factors identified at the time of TURBT - number of tumors, tumor size, prior recurrence history, pathologic stage, concomitant carcinoma in situ, and grade - are each assigned a weighted score. Two separate total scores, one for recurrence risk and one for progression risk, are then mapped to 1-year and 5-year probability estimates from lookup tables. The tool is endorsed in the European Association of Urology (EAU) guidelines on NMIBC as a standard decision-support aid for choosing surveillance intensity and adjuvant intravesical therapy.
How the two-score system works
The EORTC model calculates two independent scores rather than one combined score, because the factors that best predict recurrence and those that best predict progression overlap but are not identical. The recurrence score can range from 0 to 17 points. It weights tumor number most heavily (up to 6 points for eight or more tumors), followed by size and prior recurrence rate (3 to 4 points each), with smaller contributions from stage, CIS, and grade. The progression score can range from 0 to 23 points. It assigns the largest weights to concomitant CIS (6 points), T1 stage (4 points), and grade 3 histology (5 points), reflecting that these pathological features most strongly predict invasion into the muscle layer. For the progression score, both 2-7 and 8-plus tumors score the same 3 points, and both prior recurrence categories score the same 2 points, because recurrence history is less predictive of progression. Once each total score is calculated, a four-band lookup table converts it to 1-year and 5-year probability ranges derived from the original trial data.
Risk categories and treatment implications
The EAU NMIBC guidelines use the EORTC scores to help stratify patients into low, intermediate, and high-risk groups for the purpose of selecting adjuvant therapy. Low recurrence score (0 points): a single intravesical instillation of chemotherapy (typically mitomycin C) immediately after TURBT is standard, and annual cystoscopy is generally sufficient surveillance. Intermediate recurrence score (1-9 points): adjuvant intravesical chemotherapy or BCG instillations for 1 year are recommended, with cystoscopy at 3 months and then every 3 to 6 months for 2 years. High recurrence score (10-17 points) or any non-zero progression score above 6: full-course BCG induction and 1 to 3 years of maintenance therapy is recommended. Any patient with a progression score above 13 (high risk) should have an early discussion about radical cystectomy, because BCG failure rates are substantial and prognosis after progression to muscle-invasive disease worsens significantly with delay. These recommendations should always be interpreted alongside complete clinical context, and specialist input is essential for individual management decisions.
Grading system and important caveats
This calculator uses the 1973 WHO three-tier grading system (G1, G2, G3) that was applied in the original Sylvester 2006 study. Many pathology reports today use the 2004 or 2016 WHO two-tier system (low grade, high grade). In broad terms, low-grade tumors correspond to G1-G2 and high-grade tumors correspond to G3, but the correspondence is imperfect and the two systems are not interchangeable. Clinicians should confirm the grading system used in the pathology report before entering values. The EORTC model applies specifically to stage Ta and T1 urothelial tumors: it does not apply to CIS alone, T2 or higher disease, upper-tract tumors, or tumors of non-urothelial histology. A newer 2016 EORTC model was developed for patients receiving BCG therapy and produces somewhat different estimates; the 2006 model used here remains the more widely cited reference for general NMIBC risk stratification.
EORTC risk score lookup tables
| Score range | Risk category | 1-year probability | 5-year probability |
|---|---|---|---|
| Recurrence score 0 | Low risk | 15% | 31% |
| Recurrence score 1-4 | Intermediate risk (lower) | 24% | 46% |
| Recurrence score 5-9 | Intermediate risk (higher) | 38% | 62% |
| Recurrence score 10-17 | High risk | 61% | 78% |
| Progression score 0 | Low risk | 0.2% | 0.8% |
| Progression score 2-6 | Low-intermediate risk | 1% | 6% |
| Progression score 7-13 | Intermediate-high risk | 5% | 17% |
| Progression score 14-23 | High risk | 17% | 45% |
Probability estimates from Sylvester et al., European Urology 2006;49:466-475. Data derived from 2,596 patients across 7 EORTC trials.
Frequently asked questions
What does the EORTC score actually measure?
The EORTC system produces two separate numeric scores. The recurrence score (0-17) estimates the probability that the bladder cancer will come back after successful removal at TURBT, typically as a new superficial tumor. The progression score (0-23) estimates the probability that the disease will advance into the muscle wall of the bladder (becoming T2 or higher), which is a more serious event requiring more aggressive treatment. Both scores are converted to 1-year and 5-year probability estimates using tables derived from clinical trial data.
Can the EORTC calculator be used for muscle-invasive bladder cancer?
No. The model was developed exclusively for non-muscle-invasive bladder cancer, specifically pTa and pT1 stage tumors. Muscle-invasive bladder cancer (T2 and above) requires entirely different prognostic tools and treatment pathways. The EORTC model also does not apply to carcinoma in situ (CIS) found in isolation, upper-tract urothelial carcinoma, or non-urothelial histologies.
What is concomitant CIS and why does it score so high?
Concomitant carcinoma in situ (CIS) is flat, high-grade urothelial cancer found alongside the main papillary tumor. It is biologically aggressive and is strongly associated with progression to muscle-invasive disease. In the EORTC progression model, the presence of CIS carries 6 points, the largest single contribution in the entire system, reflecting its powerful predictive value for disease advancement.
Why does tumor number score differently for recurrence versus progression?
For the recurrence score, the number of tumors is the most heavily weighted factor, with 8 or more tumors scoring 6 points and 2-7 tumors scoring 3 points. The distinction matters for recurrence because more tumors indicate widespread urothelial field change and a higher chance of visible recurrence after resection. For the progression score, both 2-7 and 8-plus tumors score the same 3 points, because extensive tumor number is less predictive of invasion into the muscle layer than pathological features like stage and grade.
How accurate are the EORTC probability estimates?
The EORTC model performs reasonably well as a population-level risk stratification tool and is better than unaided clinical judgment. However, validation studies in independent cohorts have found that the model tends to overestimate absolute recurrence rates in contemporary practice, possibly because systematic use of immediate post-TURBT instillation and BCG maintenance has improved outcomes compared with the original trial era. The probabilities should be treated as relative risk estimates for clinical decision-making rather than precise individual predictions.
Should I use the 2006 or 2016 EORTC model?
The 2006 EORTC model, implemented in this calculator, applies to all NMIBC patients at the time of initial risk stratification. The 2016 EORTC model was developed specifically to predict outcomes in patients who are receiving or have received BCG immunotherapy, so it uses different inputs and produces different estimates. If you are counseling a patient about adjuvant therapy choice before BCG is started, the 2006 model is the appropriate reference. Once a patient is established on BCG therapy, the 2016 model and BCG-response criteria become more relevant.