Clinical significance of K-ras and BRAF mutations in Chinese colorectal cancer patients

Table 1 Characteristics of colorectal cancer patients in this study

Terms	n (%)
No. of patients	118
Median age (yr)	61
Gender
Male	71 (60.2)
Female	47 (39.8)
Colorectal segment
Cecum	5 (4.2)
Ascending colon	23 (19.5)
Transversal colon	8 (6.8)
Descending colon	5 (4.2)
Sigmoid	25 (21.2)
Rectum	52 (44.1)
UICC stage
I	18 (15.3)
II	48 (40.7)
IIA	32 (27.1)
IIB	16 (13.6)
III	37 (31.4)
IIIA	5 (4.2)
IIIB	25 (21.2)
IIIC	7 (5.9)
IV	15 (12.7)

UICC: Union for International Cancer Control.

Table 2 Primers designed for amplification and pyrosequencing assay of K-ras and BRAF genes

	Primer sequence	Product (bp)
K-ras gene codon 12 & 13 (exon 1)	Forward: 5'-GCAGTCAACTGGAATTTTCATG-3'	431
	Reverse: 5'-biotin-GAAACCCAAGGTACATTTCAGA-3'
	Pyrosequencing assay: 5'-TGTGGTAGTTGGAGCT- 3'
K-ras gene codon 61 (exon 2)	Forward:5'-ATCCAGACTGTGTTTCTCCCTTC-3'	378
	Reverse: 5'-biotin-ACTGCTCTAATCCCCCAAGAACT-3'
	Pyrosequencing assay: 5'-TATTCACGACACAGCAGGT-3'
BRAF gene codon 600 (exon 15)	Forward: 5'-ACAAGCCTTCAAAAATGAAGTAG-3'	362
	Reverse: 5'-biotin-ATCCAGACAACTGTTCAAACTGA-3'
	Pyrosequencing assay: 5'-GGTGATTTTGGTCTAACTACA-3'

Table 3 Mutations of K-ras codons 12, 13, and 61 DNA detected by pyrosequencing assay

	Wild type (AA)	Point mutation (AA)	No. of mutations (%)
K-ras codon 12	GGT (Gly)	AGT (Ser)	2 (1.7)
	GGT (Gly)	GAT (Asp)	16 (13.6)
	GGT (Gly)	GCT (Ala)	2 (1.7)
	GGT (Gly)	GTT (Val)	8 (6.8)
K-ras codon 13	GGC (Gly)	GAC (Asp)	12 (10.2)
K-ras codon 61	CAA (Gln)	CAT (His)	1 (0.8)

AA: Amino acid; Gly: Glycinel; Gln: Glutamine; Ser: Serine; Asp: Aspartic acid; Ala: Alanine; Val: Valine; His: Histidine.

Table 4 Correlation between K-ras mutations and clinicopathological factors in colorectal cancer n (%)

Terms	All	Wild type	Mutation type	P value
No. of patients	118	77 (65.3)	41 (34.7)
Gender				0.037
Male	71	51 (71.8)	20 (28.2)
Female	47	26 (55.3)	21 (44.7)
Median age (yr)	61.0	64.0	60.0	0.728
Males	65.0	65.0	65.5
Females	60.0	60.5	58.0
Colorectal segment				0.559
Cecum	5	1 (20.0)	4 (80.0)
Ascending colon	23	17 (73.9)	6 (26.1)
Transversal colon	8	4 (50.0)	4 (50.0)
Descending colon	5	4 (80.0)	1 (20.0)
Sigmoid	25	16 (64.0)	9 (36.0)
Rectum	52	35 (67.3)	17 (32.7)
Differentiation				0.761
Poor	17	12 (70.6)	5 (29.4)
Moderate	42	25 (59.5)	17 (40.5)
Well	59	40 (67.8)	19 (32.2)
UICC classification				0.631
I	18	9 (50.0)	9 (50.0)
II	48	37 (77.1)	11 (22.9)
III	37	23 (62.2)	14 (37.8)
IV	15	8 (53.3)	7 (46.7)
Bowel wall invasion (pT)				0.120
pT1	2	1 (50.0)	1 (50.0)
pT2	21	11 (52.4)	10 (47.6)
pT3	65	43 (66.2)	22 (33.8)
pT4	30	22 (73.3)	8 (26.7)
Lymph node metastasis (pN)				0.585
pN0	69	47 (68.1)	22 (31.9)
pN1-2	49	31 (63.3)	18 (36.7)
Distant metastasis (pM)				0.301
pM0	103	70 (68.0)	33 (32.0)
pM1	15	8 (53.3)	7 (46.7)

UICC: Union for International Cancer Control.

Table 5 Relationship in K-ras mutation between gender and tumor location

	No. of K-ras mutated patients (%)		Total No. of patients
	Colon	Rectum
Male	12 (16.9)	8 (11.2)	71
Female	5 (10.6)	16 (34)	47