Different oncological features of colorectal cancer codon-specific KRAS mutations: Not codon 13 but codon 12 have prognostic value

Table 1 Clinicopathologic characteristics of the study patients

Clinical characteristics (n = 2203)	Value1
Age (yr)	64.7 ± 12.2
Sex
Male	1264 (57.4)
Female	939 (42.6)
Body mass index (kg/m2)	23.9 ± 3.3
ASA score
1	575 (26.1)
2	1412 (64.1)
3	211 (9.6)
4	5 (0.2)
Cancer location
Cecum	46 (2.1)
Ascending colon	386 (17.5)
Hepatic flexure	88 (4.0)
Transverse colon	115 (5.2)
Splenic flexure	18 (0.8)
Descending colon	79 (3.6)
Sigmoid colon	771 (35.0)
Rectum	700 (31.7)
Preoperative CEA (ng/mL)	7.7 ± 42.3
Diverting stoma
Ileostomy	435 (19.7)
Colostomy	62 (2.8)
T stage
0	18 (0.8)
1	275 (12.5)
2	383 (17.4)
3	1282 (58.2)
4	245 (11.1)
N stage
0	1286 (58.4)
1	639 (29.0)
2	278 (12.6)
Tumor size (cm)	4.4 ± 2.4
Lymphatic invasion	597 (27.1)
Vascular invasion	469 (21.3)
Perineural invasion	934 (42.4)
Harvested lymph nodes	45.3 ± 21.2
Metastatic lymph nodes	1.4 ± 2.9
Adjuvant/Neoadjuvant therapy
Colon
Adjuvant therapy-stage II	274 (51.4)
Adjuvant therapy-stage III	575 (90.0)
Rectum
Neoadjuvant therapy	200 (28.6)
Operative first-Adjuvant therapy	264 (52.8)

¹Results are reported as mean ± SD or as frequency (percent).

ASA: American Society of Anesthesiologists; CEA: Carcinoembryonic antigen; AJCC: American Joint Committee on Cancer.

Table 2 Univariable analysis¹ of each codon-specific KRAS mutation

	KRAS overall2			KRAS Codon 12			KRAS Codon 13			KRAS Codon 61
	WT (%)	MT (%)	P value	WT (%)	MT (%)	P value	WT (%)	MT (%)	P value	WT (%)	MT (%)	P value
Age			0.418			0.734			0.698			0.246
< 65 yr	644 (62.8)	382 (37.2)		745 (72.6)	281 (27.4)		936 (91.1)	91 (8.9)		1016 (99.0)	10 (1.0)
≥ 65 yr	719 (61.1)	458 (38.9)		847 (72.0)	330 (28.0)		1067 (90.7)	110 (9.3)		1160 (98.5)	18 (1.5)
Sex			< 0.001			< 0.001			0.006			0.238
Male	851 (67.3)	413 (32.7)		961 (76.0)	303 (24.0)		1167 (92.3)	97 (7.7)		1251 (99.0)	13 (1.0)
Female	512 (54.5)	427 (45.5)		631 (67.2)	308 (32.8)		836 (88.9)	104 (11.1)		924 (98.4)	15 (1.6)
BMI			0.098			0.347			0.485			0.104
< 25 kg/m2	853 (60.6)	555 (39.4)		1008 (71.6)	400 (28.4)		1275 (90.6)	133 (9.4)		1386 (98.4)	22 (1.6)
≥ 25 kg/m2	510 (64.2)	285 (35.8)		584 (73.5)	211 (26.5)		727 (91.4)	68 (8.6)		789 (99.2)	6 (0.8)
ASA score			0.010			0.002			0.942			0.347
1-2	1212 (61.0)	775 (39.0)		1417 (71.3)	570 (28.7)		1806 (90.9)	181 (9.1)		1963 (98.8)	24 (1.2)
3-4	151 (69.9)	65 (30.1)		175 (81.0)	41 (19.0)		196 (90.7)	20 (9.3)		212 (98.1)	4 (1.9)
Cancer location (1)3			< 0.001			0.002			< 0.001			0.219
Right-sided	329 (51.8)	306 (48.2)		429 (67.6)	206 (32.4)		546 (86.0)	89 (14.0)		624 (98.3)	11 (1.7)
Left-sided	1034 (65.9)	534 (34.1)		1163 (74.2)	405 (25.8)		1456 (92.9)	112 (7.1)		1552 (98.9)	17 (1.1)
Cancer location (2)4			0.092			0.405			0.117			0.966
Colon	912 (60.7)	591 (39.3)		1078 (71.7)	425 (28.3)		1356 (90.2)	147 (9.8)		1484 (98.7)	19 (1.3)
Rectum	451 (64.4)	249 (35.6)		514 (73.4)	186 (26.6)		646 (92.3)	54 (7.7)		691 (98.7)	9 (1.3)
Preoperative CEA			< 0.001			< 0.001			0.037			0.301
< 5.0 ng/mL	1131 (64.7)	616 (35.3)		1299 (74.4)	448 (25.6)		1599 (91.5)	148 (8.5)		1727 (98.9)	20 (1.1)
≥ 5.0 ng/mL	232 (50.9)	224 (49.1)		293 (64.3)	163 (35.7)		403 (88.4)	53 (11.6)		448 (98.2)	8 (1.8)
Diverting stoma			0.001			0.071			0.029			0.131
No	1024 (60.0)	682 (40.0)		1217 (71.3)	489 (28.7)		1538 (90.2)	168 (9.8)		1681 (98.5)	25 (1.5)
Yes	339 (68.2)	158 (31.8)		375 (75.5)	122 (24.5)		464 (93.4)	33 (6.6)		494 (99.4)	3 (0.6)
T stage			0.008			0.003			0.488			0.139
T0-2	446 (66.0)	230 (34.0)		517 (76.5)	159 (23.5)		610 (90.2)	66 (9.8)		671 (99.3)	5 (0.7)
T3-4	917 (60.1)	610 (39.9)		1075 (70.4)	452 (29.6)		1392 (91.2)	135 (8.8)		1504 (98.5)	23 (1.5)
N stage			0.012			0.046			0.617			0.094
N0	824 (64.1)	462 (35.9)		950 (73.9)	336 (26.1)		1172 (91.1)	114 (8.9)		1274 (99.1)	12 (0.9)
N1-2	539 (58.8)	378 (41.2)		642 (70.0)	275 (30.0)		830 (90.5)	87 (9.5)		901 (98.3)	16 (1.7)
MSI status			0.003			0.001			0.458			0.973
MSS	1138 (61.0)	728 (39.0)		1327 (71.1)	539 (28.9)		1701 (91.2)	165 (8.8)		1842 (98.7)	24 (1.3)
MSI-low	90 (58.8)	63 (41.2)		110 (71.9)	43 (28.1)		135 (88.2)	18 (11.8)		151 (98.7)	2 (1.3)
MSI-high	135 (73.4)	49 (26.6)		155 (84.2)	29 (15.8)		166 (90.2)	18 (9.8)		182 (98.9)	2 (1.1)
Tumor size (cm)	4.3 ± 2.4	4.6 ± 2.3	0.005	4.3 ± 2.5	4.6 ± 2.1	0.001	4.4 ± 2.3	4.6 ± 2.7	0.837	4.4 ± 2.4	4.5 ± 2.1	0.708
Lymphatic invasion			0.005			0.099			0.080			0.302
No	1022 (63.6)	584 (36.4)		1176 (73.2)	430 (26.8)		1470 (91.5)	136 (8.5)		1589 (98.9)	18 (1.1)
Yes	341 (57.1)	256 (42.9)		416 (69.7)	181 (30.3)		532 (89.1)	65 (10.9)		587 (98.3)	10 (1.7)
Vascular invasion			0.090			0.047			0.614			0.061
No	1057 (61.0)	677 (39.0)		1236 (71.3)	498 (28.7)		1573 (90.7)	161 (9.3)		1716 (99.0)	18 (1.0)
Yes	306 (65.2)	163 (34.8)		356 (75.9)	113 (24.1)		429 (91.5)	40 (8.5)		459 (97.9)	10 (2.1)
Perineural invasion			0.003			0.027			0.387			0.048
No	819 (64.5)	450 (35.5)		940 (74.1)	329 (25.9)		1159 (91.3)	110 (8.7)		1258 (99.1)	11 (0.9)
Yes	544 (58.2)	390 (41.8)		652 (69.8)	282 (30.2)		843 (90.3)	91 (9.7)		917 (98.2)	17 (1.8)
Harvested LN	44.5 ± 20.6	46.5 ± 22.1	0.040	45.0 ± 21.1	45.9 ± 21.6	0.500	45.0 ± 20.9	47.9 ± 24.1	0.079	45.2 ± 21.3	47.7 ± 16.6	0.208
Metastatic LN	1.4 ± 3.1	1.3 ± 2.6	0.420	1.4 ± 3.1	1.3 ± 2.4	0.406	1.4 ± 2.9	1.4 ± 3.1	0.832	1.4 ± 2.9	1.4 ± 1.9	0.149

¹The continuous variables were compared using either independent t-test or Mann-Whitney U test; the categorical variables were compared using Chi-square or Fisher’s exact test.

²Kirsten rat sarcoma viral oncogene homolog overall indicates at least one mutation within codon 12, 13, or 61.

³Right-sided: From the cecum to distal 2/3 transverse colon; Left-sided: From the splenic flexure to rectum.

⁴Rectum: Below the pelvic inlet (an imaginary line drawn from the sacral promontory to the pubic symphysis).

KRAS: Kirsten rat sarcoma viral oncogene homolog; WT: Wild-type; MT: Mutation; BMI: Body mass index; ASA: American Society of Anesthesiologists; CEA: Carcinoembryonic antigen; MSI: Microsatellite instability; MSS: Microsatellite stable; LN: Lymph node.

Table 3 Univariable and Cox regression analyses of KRAS mutations for determination of recurrence-related factors

	Recurrence			Multivariable Cox regression analysis2
	Absent1 (n = 1998)	Present1 (n = 205)	P value	HR	95%CI		P value
					Lower	Upper
Age (yr)			0.716
< 65	933 (46.7)	93 (45.4)		-	-	-	-
≥ 65	1065 (53.3)	112 (54.6)		-	-	-
Sex			0.616
Male	1143 (57.2)	121 (59.0)		-	-	-	-
Female	855 (42.8)	84 (41.0)		-	-	-
BMI			0.094
< 25 kg/m2	1266 (63.4)	142 (69.3)		-	-	-	-
≥ 25 kg/m2	732 (36.6)	63 (30.7)		-	-	-
ASA score			0.980
1-2	1802 (90.2)	185 (90.2)		-	-	-	-
3-4	196 (9.8)	20 (9.8)		-	-	-
Cancer location (1)3			0.860
Right-sided	577 (28.9)	58 (28.3)		-	-	-	-
Left-sided	1421 (71.1)	147 (71.7)		-	-	-
Cancer location (2)4
Colon	1376 (68.9)	127 (62.0)	0.043	1.000
Rectum	622 (31.1)	78 (38.0)		1.053	0.718	1.545	0.791
Preoperative CEA			< 0.001
< 5.0 ng/mL	1607 (80.4)	140 (68.3)		1.000
≥ 5.0 ng/mL	391 (19.6)	65 (31.7)		1.158	0.849	1.579	0.354
Diverting stoma			< 0.001
No	1568 (78.5)	138 (67.3)		1.000
Yes	430 (21.5)	67 (32.7)		1.874	1.260	2.787	0.002
T stage			< 0.001
T0-2	659 (33.0)	17 (8.3)		1.000
T3-4	1339 (67.0)	188 (91.7)		2.620	1.479	4.641	0.001
N stage			< 0.001
N0	1230 (61.6)	56 (27.3)		1.000
N1-2	768 (38.4)	149 (72.7)		2.001	1.399	2.861	< 0.001
MSI status			0.037
MSS	1680 (84.1)	186 (90.7)		0.855	0.342	2.138	0.738
MSI-low	143 (7.2)	10 (4.9)		1.284	0.643	2.566	0.479
MSI-high	175 (8.8)	9 (4.4)		1.000
Tumor size (cm)	4.3 ± 2.4	4.9 ± 2.1	< 0.001	0.997	0.927	1.074	0.944
Lymphatic invasion			< 0.001
No	1493 (74.7)	113 (55.1)		1.000
Yes	505 (25.3)	92 (44.9)		1.324	0.977	1.793	0.070
Vascular invasion			< 0.001
No	1615 (80.8)	119 (58.0)		1.000
Yes	383 (19.2)	86 (42.0)		1.578	1.164	2.139	0.003
Perineural invasion			< 0.001
No	1211 (60.6)	58 (28.3)		1.000
Yes	787 (39.4)	147 (71.7)		1.684	1.194	2.376	0.003
Harvested LN	45.3 ± 21.2	44.9 ± 21.4	0.705	-	-	-	-
Metastatic LN	1.2 ± 2.6	3.3 ± 4.5	< 0.001	1.028	0.995	1.061	0.095
KRAS Codon 12
Wild-type	1459 (73.0)	133 (64.9)	0.013	1.000
Mutation	539 (27.0)	72 (35.1)		1.399	1.034	1.894	0.030
KRAS Codon 13
Wild-type	1809 (90.5)	193 (94.1)	0.088	1.000
Mutation	189 (9.5)	12 (5.9)		0.637	0.350	1.160	0.140
KRAS Codon 61
Wild-type	1975 (98.8)	200 (97.6)	0.176	1.000
Mutation	23 (1.2)	5 (2.4)		1.950	0.790	4.812	0.147

¹Results are reported as mean ± SD or as number (percent).

²No values indicated variables do not match the covariance input criterion (P < 0.1 in univariable analysis).

³Right-sided: From the cecum to distal 2/3 transverse colon; Left-sided: From the splenic flexure to rectum.

⁴Rectum: Below the pelvic inlet (an imaginary line drawn from the sacral promontory to the pubic symphysis).

KRAS: Kirsten rat sarcoma viral oncogene homolog; HR: Hazard ratio; CI: Confidence interval; BMI: Body mass index; ASA: American Society of Anesthesiologists; CEA: Carcinoembryonic antigen; MSI: Microsatellite instability; MSS: Microsatellite stable; LN: Lymph node.

Table 4 Cox regression analyses of recurrence-related factors in subgroups based on tumor location in the colon and rectum

	Colon (n = 1503)		Rectum (n = 700)
	HR (95%CI)	P value	HR (95%CI)	P value
Preoperative CEA ≥ 5.0 ng/mL	1.290 (0.860-1.933)	0.218	1.215 (0.705-2.220)	0.444
Diverting stoma (+)	0.903 (0.394-2.067)	0.809	1.249 (0.755-2.065)	0.386
T3-4 stage (vs T0-2)	1.211 (0.737-1.991)	0.450	1.079 (0.601-1.939)	0.799
N1-2 stage (vs N0)	1.241 (0.863-1.784)	0.244	1.126 (0.649-1.954)	0.674
Tumor size (cm)	1.100 (1.011-1.198)	0.027	1.077 (0.948-1.223)	0.256
Lymphatic invasion	1.342 (0.919-1.960)	0.128	0.971 (0.562-1.676)	0.915
Vascular invasion	1.981 (1.362-2.880)	< 0.001	1.401 (0.841-2.334)	0.195
Perineural invasion	1.793 (1.200-2.679)	0.004	3.358 (1.885-5.983)	< 0.001
Metastatic LN	1.048 (1.014-1.083)	0.006	1.095 (1.017-1.178)	0.016
KRAS Codon 12 mutation	1.496 (1.019-2.196)	0.040	1.492 (0.902-2.466)	0.119
KRAS Codon 13 mutation	0.831 (0.412-1.678)	0.606	0.481 (0.146-1.578)	0.227
KRAS Codon 61 mutation	2.385 (0.730-7.795)	0.150	2.270 (0.511-10.088)	0.282

KRAS: Kirsten rat sarcoma viral oncogene homolog; HR: Hazard ratio; CI: Confidence interval; CEA: Carcinoembryonic antigen; MSI: Microsatellite instability; MSS: Microsatellite stable; LN: Lymph node.

Table 5 Cox regression analyses of recurrence-related factors in subgroups based on microsatellite instability status: Microsatellite stable/microsatellite instability-low versus microsatellite instability-high

	MSS/MSI-low (n = 2019)		MSI-high (n = 184)1
	HR (95%CI)	P value	HR (95%CI)	P value
Preoperative CEA ≥ 5.0 ng/mL	1.178 (0.839-1.653)	0.344	8.321 (1.387-49.920)	0.020
Rectal cancer (vs colon cancer)	1.238 (0.850-1.804)	0.266	-	-
Diverting stoma (+)	1.069 (0.707-1.617)	0.752	2.431 (0.139-42.442)	0.543
T3-4 stage (vs T0-2)	1.175 (1.038-1.202)	0.407	0.284 (0.020-4.032)	0.353
N1-2 stage (vs N0)	1.190 (0.879-1.610)	0.260	1.000 (0.151-6.643)	1.000
Tumor size (cm)	1.117 (1.038-1.202)	0.003	0.991 (0.713-1.379)	0.960
Lymphatic invasion	1.242 (0.909-1.698)	0.174	1.154 (0.149-8.923)	0.891
Vascular invasion	1.740 (1.282-2.363)	< 0.001	0.009 (0.000-29.277)	0.255
Perineural invasion	2.335 (1.663-3.279)	< 0.001	0.538 (0.049-5.909)	0.613
Metastatic LN	1.050 (1.020-1.081)	0.001	1.442 (0.865-2.402)	0.160
KRAS Codon 12 mutation	1.467 (1.077-1.998)	0.015	2.508 (0.406-15.510)	0.323
KRAS Codon 13 mutation	0.713 (0.390-1.301)	0.270	-	-
KRAS Codon 61 mutation	2.265 (0.915-5.605)	0.077	-	-

¹No values: Due to a small sample size, the hazard ratio and confidence interval were not pre.

MSI: Microsatellite instability; MSS: Microsatellite stable; HR: Hazard ratio; CI: Confidence interval; CEA: Carcinoembryonic antigen; MSI: Microsatellite instability; MSS: Microsatellite stable; LN: Lymph node.