Table 2. Pooled frequency of MLH1 promoter methylation in colorectal cancer patients with different molecular features.
| Classification | No. ofstudies | No. ofdetectedcases | No. ofmethylationcases | Frequency and95%CI (%) | Heterogeneity | Publication bias | ||
| I2 (%) | P | Begg’stest P | Egger’stest P | |||||
| CRC(total) MSI Status | ||||||||
| MSI-H | 12 | 968 | 566 | 62.6(54.0–70.4)* | 78.288 | 0.000 | 0.411 | 0.049 |
| MSI-L | 4 | 344 | 24 | 12.2(3.0–38.2)* | 90.733 | 0.000 | 1.000 | 0.845 |
| MSI | 16 | 1325 | 576 | 55.8(45.2–65.8)* | 89.197 | 0.000 | 0.280 | 0.002 |
| MSS | 10 | 1791 | 155 | 5.2(2.2–11.6)* | 88.938 | 0.000 | 0.655 | 0.068 |
| LS- MSI-H | 5 | 95 | 11 | 15.3(8.8–25.4) | 0.000 | 0.517 | 0.050 | 0.160 |
| SCRC MSI Status | ||||||||
| MSI-H | 11 | 249 | 188 | 73.6(67.3–79.0) | 42.882 | 0.000 | 0.119 | 0.228 |
| MSI | 7 | 193 | 125 | 67.3(47.1–82.7)* | 79.255 | 0.000 | 0.293 | 0.253 |
| MSS | 4 | 264 | 51 | 17.5(10.0–29.0) | 35.109 | 0.202 | 0.174 | 0.014 |
| CRC(total) MLH1expression | ||||||||
| Positive | 2 | 67 | 7 | 11.9(1.5–53.8)* | 83.531 | 0.014 | – | – |
| Negative | 5 | 106 | 73 | 66.5(44.4–83.2)* | 73.534 | 0.004 | 1.000 | 0.981 |
| MSI-H- Loss of MLH1 protein | 5 | 247 | 201 | 80.8(75.3–85.3) | 0.000 | 0.644 | 0.624 | 0.321 |
| SCRC-MLH1 expression | ||||||||
| Positive | 6 | 308 | 25 | 9.8(3.4–25.2)* | 76.529 | 0.001 | 0.851 | 0.366 |
| Negative | 10 | 156 | 108 | 69.8(45.5–86.5)* | 78.786 | 0.000 | 0.089 | 0.083 |
| MSI-H- Loss of MLH1 protein | 3 | 64 | 56 | 86.3(75.3–92.9) | 0.000 | 0.618 | 0.602 | 0.782 |
| LS- Loss of MLH1 protein | 5 | 169 | 65 | 37.8 (25.3–52.1)* | 62.057 | 0.000 | 0.142 | 0.155 |
| CRC(total)BRAF situation | ||||||||
| Mutant | 3 | 138 | 70 | 53.2(27.7–77.2)* | 67.744 | 0.045 | 0.602 | 0.572 |
| Wild type | 3 | 764 | 113 | 13.7(5.1–32.0)* | 90.433 | 0.000 | 0.602 | 0.792 |
| CRC(total)KRAS situation | ||||||||
| Mutant | 3 | 353 | 41 | 14.0(10.2–19.0) | 9.722 | 0.330 | 0.117 | 0.119 |
| Wild type | 3 | 570 | 135 | 21.8(13.2–33.8)* | 77.209 | 0.012 | 0.602 | 0.699 |
Abbreviations: CRC, colorectal cancer; LS, lynch syndrome; MMR, mismatch repair; SCRC, sporadic colorectal cancer; MSI, Microsatellite instability; MSS, microsatellite stability; MSI-L, lower-level microsatellite instability; MSI-H, high-level microsatellite instability.
*
Random effect estimate.