BRAF and K-ras mutations in colorectal polyps
| Polyp type | No of cases | BRAF (V599E) | p Value** | K-ras | p Value** |
|---|---|---|---|---|---|
| HP, hyperplastic polyp; MP, mixed polyp; SA, serrated adenoma; AD, tubular adenoma and tubulovillous adenoma; CIMP, CpG island methylator phenotype. | |||||
| *CIMP status was determined using four markers (MINT 1, MINT 2, MINT 12, and MINT 31); CIMP-high, 3–4 markers methylated; CIMP-low, 1–2 markers methylated; CIMP-negative, no marker methylated. | |||||
| †HP or MP showing atypical features, as described by Torlakovic et al and Goldstein et al.11,13 | |||||
| ‡Serrated polyps (polyps with serrated architecture) include HP, MP, and SA. | |||||
| §Range 1–16 mm; mean (SEM) 5.4 (0.5) mm. | |||||
| ¶Two SA were not available for size measurement. | |||||
| **We used either Pearson’s χ2 test or Fisher’s exact test where appropriate to compare all variables. | |||||
| ††p value was analysed by χ2 test for five categories (classical HP, variant HP, MP, SA, and AD). | |||||
| ‡‡p value is for comparison of 27 classical HP and 16 variant HP, as described by Torlakovic et al and Goldstein et al.11,13 | |||||
| §§p value is for comparison of 24 polyps (16 HP and eight MP) showing atypical features and 28 polyps (27 HP and one MP) lacking atypical features. | |||||
| ¶¶p value is for comparison of 57 serrated polyps and 28 conventional adenomas. | |||||
| Histology | <0.0001†† | 0.02†† | |||
| HP | 43 | 17 (40%) | <0.001‡‡ | 8 (19%) | 0.02‡‡ |
| Classical HP | 27 | 5 (19%) | 8 (30%) | ||
| Variant HP† | 16 | 12 (75%) | 0 (0%) | ||
| MP | 9 | 8 (89%) | 0 (0%) | ||
| Without atypical histology† | 1 | 0 (0%) | 0 (0%) | ||
| With atypical histology† | 8 | 8 (100%) | <0.0001§§ | 0 (0%) | <0.01§§ |
| SA | 5 | 1 (20%) | 1 (20%) | ||
| AD | 28 | 0 (0%) | <0.0001¶¶ | 11 (39%) | 0.03¶¶ |
| Characteristics of serrated polyps‡ | 57 | ||||
| Location | 0.01 | 0.07 | |||
| Right sided | 31 | 19 (61%) | 2 (6%) | ||
| Left sided | 26 | 7 (27%) | 7 (27%) | ||
| Size§ | 0.02 | 0.25 | |||
| 1-5 mm | 38 | 13 (34%) | 8 (21%) | ||
| 6 mm or more | 17 | 12 (71%) | 1 (6%) | ||
| Unknown | 2¶ | 1 | 0 | ||
| Origin | <0.0001 | 0.06 | |||
| Hyperplastic polyposis | 25 | 22 (88%) | 1 (4%) | ||
| Sporadic | 32 | 4 (13%) | 8 (25%) | ||
| CIMP-status* | 0.002 | 0.009 | |||
| CIMP-high | 25 | 18 (72%) | 1 (4%) | ||
| CIMP-low | 23 | 7 (30%) | 4 (17%) | ||
| CIMP-negative | 8 | 1 (13%) | 4 (50%) | ||
| Unknown | 1 | 0 | 0 | ||