Table 2

BRAF and K-ras mutations in colorectal polyps

Polyp typeNo of casesBRAF (V599E)p Value**K-rasp 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.
    HP4317 (40%)<0.001‡‡8 (19%)0.02‡‡
        Classical HP275 (19%)8 (30%)
        Variant HP†1612 (75%)0 (0%)
    MP98 (89%)0 (0%)
        Without atypical histology†10 (0%)0 (0%)
        With atypical histology†88 (100%)<0.0001§§0 (0%)<0.01§§
    SA51 (20%)1 (20%)
    AD280 (0%)<0.0001¶¶11 (39%)0.03¶¶
Characteristics of serrated polyps‡57
        Right sided3119 (61%)2 (6%)
        Left sided267 (27%)7 (27%)
        1-5 mm3813 (34%)8 (21%)
        6 mm or more1712 (71%)1 (6%)
        Hyperplastic polyposis2522 (88%)1 (4%)
        Sporadic324 (13%)8 (25%)
        CIMP-high2518 (72%)1 (4%)
        CIMP-low237 (30%)4 (17%)
        CIMP-negative81 (13%)4 (50%)