Observational Study
Copyright ©The Author(s) 2015.
World J Gastroenterol. Jan 28, 2015; 21(4): 1275-1283
Published online Jan 28, 2015. doi: 10.3748/wjg.v21.i4.1275
Table 1 Patient characteristics according to BRAF or KRAS status n (%)
CharacteristicsKRAS status
BRAF status
Wild-type n = 500Mutant n = 312P valueWild-type n = 771Mutant n = 40P value
Age (yr)0.110.40
mean ± SD63.5 ± 10.364.7 ± 10.363.9 ± 10.365.4 ± 11.6
Gender0.020.006
Male308 (62)166 (53)459 (60)15 (38)
Female192 (38)146 (47)312 (40)25 (63)
Tumor location0.37< 0.001
Proximal134 (27)98 (31)201 (26)31 (78)
Distal213 (43)125 (40)332 (43)5 (13)
Rectum153 (31)89 (29)238 (31)4 (10)
Histological grade0.24< 0.001
Well/moderate472 (94)288 (92)728 (94)31 (78)
Poor/mucinous28 (6)24 (8)43 (6)9 (23)
T stage0.120.89
152 (10)31 (10)79 (10)4 (10)
2106 (21)46 (15)145 (19)7 (18)
3286 (57)200 (64)462 (60)23 (58)
456 (11)35 (11)85 (11)6 (15)
LN metastasis0.180.96
Yes180 (36)127 (41)292 (38)15 (38)
No320 (64)185 (59)479 (62)25 (63)
TNM stage0.090.92
I125 (25)58 (19)173 (22)10 (25)
II195 (39)127 (41)306 (40)15 (38)
III180 (36)127 (41)292 (38)15 (38)
Adjuvant chemotherapy0.440.57
Yes217 (43)144 (46)344 (45)16 (40)
No283 (57)168 (54)427 (55)24 (60)
MSI status0.33< 0.001
MSS/MSI-L455 (91)290 (93)728 (94)16 (40)
MSI-H45 (9)22 (7)43 (6)24 (60)
Table 2 Univariate prognostic analysis of disease-free survival and overall survival
CharacteristicsDisease-free survival
Overall survival
HR95%CIHR95%CI
Age (yr)
< 651Reference1Reference
≥ 651.731.35-2.282.211.64-2.98
Gender
Female1Reference1Reference
Male1.571.20-2.061.571.16-2.13
Tumor location
Proximal1Reference1Reference
Distal0.920.67-1.250.90.64-1.26
Rectum1.170.85-1.620.970.67-1.40
Histological grade
Well/moderate1Reference1Reference
Poor/mucinous1.530.97-2.421.430.84-2.42
AJCC stage
I1Reference1Reference
II2.61.61-4.192.261.36-3.75
III4.682.95-7.423.492.14-5.70
Adjuvant chemotherapy
No1Reference1Reference
Yes1.240.96-1.601.291.10-1.51
MSI
MSS/MSI-L1Reference1Reference
MSI-H0.710.42-1.200.920.54-1.59
KRAS
Wild-type1Reference1Reference
Mutant1.351.04-1.741.441.08-1.92
BRAF
Wild-type1Reference1Reference
Mutant1.380.82-2.321.570.90-2.76
Table 3 Prognostic effects of microsatellite instability, KRAS, and BRAF status in Cox proportional models
Disease-free survival1
Overall survival1
HR (95%CI)P valueHR (95%CI)P value
MSI
MSS/MSI-L1 (reference)0.141 (reference)0.53
MSI-H0.64 (0.35-1.16)0.81 (0.42-1.56)
KRAS
Wild-type1 (reference)0.031 (reference)0.01
Mutant1.35 (1.03-1.75)1.46 (1.09-1.97)
BRAF
Wild-type1 (reference)0.011 (reference)0.02
Mutant2.20 (1.19-4.06)2.30 (1.15-4.71)
Table 4 Prognostic Effects of KRAS and BRAF mutations according to microsatellite instability status
KRAS
BRAF
HR (95%CI)P valueHR (95%CI)P value
DFS1
MSS/MSI-L1.37 (1.05-1.80)0.952.06 (0.96-4.43)0.91
MSI-H1.34 (0.34-5.24)2.46 (0.49-12.4)
OS1
MSS/MSI-L1.49 (1.10-2.02)0.702.74 (1.19-6.30)0.44
MSI-H1.39 (0.33-5.78)1.18 (0.23-6.02)