Table 1.
Microsatellite Instability (MI) as Determined by Various Measures of Instability
| Instability measure | Overall MI | MI in proximal tumors | MI in distal tumors | P value* |
|---|---|---|---|---|
| 10 tetranucleotides | 13.8% (63/457) | 23.9% (54/226) | 4.0% (8/201) | < 0.001 |
| Consensus panel | 12.5% (56/448) | 22.6% (49/217) | 2.5% (5/202) | < 0.001 |
| BAT-26 | 11.4% (53/466) | 21.2% (47/222) | 2.3% (5/213) | < 0.001 |
| TGFβRII | 10.1% (47/466) | 19.5% (44/226) | 1.4% (3/210) | < 0.001 |
| Any coding mononucleotide | 11.9% (57/481) | 21.4% (49/229) | 3.2% (7/220) | < 0.001 |
*All P values based on chi-square test comparing the percentage of proximal tumors with microsatellite instability versus the percentage of distal tumors with microsatellite instability.