MSI test result parameters for diagnosis of HNPCC in individuals unselected by age of onset or family history1-a
| MSI detected in: | One carcinoma | One adenoma | Two carcinomas | Two adenomas |
|---|---|---|---|---|
| Sensitivity | 95% | 95% | 90% | 81% |
| Specificity | 86% | 98% | 98% | >99% |
| Positive predictive value | 6% | 32% | 29% | 95% |
| Negative predictive valueb | >99% | >99% | 98% | >99% |
↵1-a based on 15% of colorectal cancers and 3% of adenomas having MSI, 1% of colorectal tumours being due to HNPCC, and 95% of HNPCC tumours having MSI, see text for details.8 ,12 ,21-26 b based on not finding MSI in a single tumour, or in both of two tumours.