Table 2.

Clinical, pathologic, and molecular characteristics according to KRAS mutation status

KRAS mutant
Mutation in either codon 12 or codon 13 onlyMutations in both codon 12 and codon 13
Clinical, pathologic, or molecular featureTotal No. (%)KRASwild type No. (%)P (wild type vs. all mutants together)Codon 12 No. (%)P (codon 12 vs. codon 13)Codon 13 No. (%)No. (%)
Total no. of patients1,2618103351106
Sex0.00490.39
Male 568 (45%)341 (42%)164 (49%)59 (54%)4 (67%)
Female 693 (55%)469 (58%)171 (51%)51 (46%)2 (33%)
Mean age (y) ± SD68.5 ± 8.768.2 ± 8.70.1869.4 ± 8.60.04467.4 ± 9.168.7 ± 5.2
Year of diagnosis0.480.0079
Before 1995 396 (31%)246 (30%)105 (31%)41 (37%)4 (67%)
1995 –1999405 (32%)260 (32%)100 (30%)44 (40%)1 (17%)
2000 –2006460 (36%)304 (38%)130 (39%)25 (23%)1 (17%)
Family history of colorectal cancer in first degree relative(s)0.350.95
Absent 1,020 (81%)649 (80%)275 (82%)90 (82%)6 (100%)
Present 241 (19%)161 (20%)60 (18%)20 (18%)0
Tumor location<0.00010.68
Cecum 210 (17%)100 (12%)82 (25%)27 (25%)1 (17%)
Ascending to transverse colon 374 (30%)260 (33%)80 (24%)32 (29%)2 (33%)
Splenic flexure to sigmoid colon 388 (31%)254 (32%)104 (31%)29 (26%)1 (17%)
Rectum 276 (22%)187 (23%)65 (20%)22 (20%)2 (33%)
Disease stage0.0260.72
I 300 (24%)199 (25%)80 (24%)20 (18%)1 (17%)
II 356 (28%)248 (31%)77 (23%)30 (27%)1 (17%)
III 324 (26%)195 (24%)95 (28%)30 (27%)4 (67%)
IV 166 (13%)95 (12%)52 (16%)19 (17%)0
Unknown 115 (9.1%)73 (9.0%)31 (9.3%)11 (10%)0
Tumor differentiation0.00180.29
Well to moderate 1,132 (90%)711 (88%)315 (95%)101 (92%)5 (83%)
Poor 122 (9.7%)94 (12%)18 (5.4%)9 (8.2%)1 (17%)
MSI status<0.00010.86
MSI low/MSS1,047 (85%)625 (79%)315 (95%)102 (94%)5 (83%)
MSI high190 (15%)166 (21%)17 (5.1%)6 (5.6%)1 (17%)
CIMP status<0.00010.40
CIMP 0518 (44%)335 (45%)140 (44%)39 (37%)4 (67%)
CIMP low456 (39%)242 (32%)154 (49%)59 (56%)1 (17%)
CIMP high203 (17%)174 (23%)21 (6.7%)7 (6.7%)1 (17%)
BRAF mutation status<0.00010.43
Wild type1,080 (86%)635 (78%)332 (99%)108 (98%)5 (83%)
Mutant 181 (14%)175 (22%)3 (0.9%)2 (1.8%)1 (17%)
PIK3CA mutation status<0.00010.48
Wild type972 (84%)656 (88%)240 (77%)72 (73%)4 (67%)
Mutant 188 (16%)88 (12%)72 (23%)26 (26%)2 (33%)
Mean LINE-1 methylation level (%) ± SD62.7 ± 9.462.8 ± 9.70.4362.8 ± 9.10.1561.3 ± 8.361.8 ± 9.0

NOTE: (%) indicates the proportion of cases with a specific clinical, pathologic, or molecular feature among each KRAS mutation status group. A P value for significance was adjusted for multiple hypothesis testing to P = 0.05/24 = 0.0021. Thus, a P value between 0.05 and 0.0021 should be regarded as of borderline significance.

Abbreviations: CIMP, CpG island methylator phenotype; MSS, microsatellite stable.