CRC MSI-H Risk Calculator
Pretreatment risk stratification for PCR-defined microsatellite instability-high colorectal cancer
Intended use: for clinicians and research staff managing patients with primary colorectal cancer before confirmatory MSI/MMR results are available. The calculator supports pretreatment risk stratification and testing prioritisation.
Not intended for: diagnosing or excluding MSI-H, deciding that confirmatory testing is unnecessary, or making treatment decisions on the calculator result alone.
Not intended for: diagnosing or excluding MSI-H, deciding that confirmatory testing is unnecessary, or making treatment decisions on the calculator result alone.
Result
Predicted MSI-H probability
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Three-zone risk group
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Model information
Outcome
PCR-defined MSI-H
Predictors
Age, tumour site, CEA, CA19-9, CA72-4, albumin, fibrinogen
Development cohort
n=1412; MSI-H=149
Temporal validation
n=898; MSI-H=89; later period at the same institution
Temporal AUC
0.850 (95% CI 0.801–0.889)
Calibration
Intercept −0.052; slope 0.905
External validation
Not yet performed independently; temporal validation at the same centre does not replace external validation.
Important: Low risk means lower predicted probability, not absence of MSI-H. Confirmatory MSI/MMR testing remains required according to the relevant clinical pathway. Absolute predicted probabilities should be interpreted cautiously outside the study setting.
Privacy: calculations are performed locally in this browser. This static calculator does not transmit or store entered values.
Interface version 1.2.5; frozen model coefficients and thresholds are unchanged.