Gastroenterol Res

Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access

Article copyright, the authors; Journal compilation copyright, Gastroenterol Res and Elmer Press Inc

Journal website https://www.gastrores.org

Original Article

Volume 13, Number 5, October 2020, pages 184-198

A Systematic Literature Review and Meta-Analysis Describing the Prevalence of KRAS, NRAS, and BRAF Gene Mutations in Metastatic Colorectal Cancer

Figure 1. Publication bias: KRAS. Egger’s regression test: two-tailed P value = 0.014. Duval and Tweedie method added 64 “missing” studies to the left of the mean, resulting in an adjusted prevalence estimate of 31.7% (30.3% - 33.2%).

Figure 2. Publication bias: BRAF. Egger’s regression test: two-tailed P value = 0.001. Duval and Tweedie method added 45 “missing” studies to the right of the mean, resulting in an adjusted prevalence estimate of 8.6% (7.8% - 9.5%).

**Table 1.** Overall Prevalence of *KRAS* Mutations in mCRC and Subgroups
	N studies^f	Summary prevalence (95% CI)	P-Het; I²	P value for heterogeneity within subgroups
^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCodon specified in papers as existing within exon 2; ^cCodon specified in papers as existing within exon 1, exon 2, or unspecified; ^dP values assess differences between global exon estimates only; ^eCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^fIndividual studies may contribute multiple prevalence estimates derived from independent study arms; so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies. mCRC: metastatic colorectal cancer; CI: confidence interval.
Overall	288	35.9% (34.6% - 37.3%)	< 0.001; 92.6%
Exon 1^a	14	35.5% (30.3% - 41.1%)	< 0.001; 75.4%
Exon 2^a	76	39.1% (37.1% - 41.3%)	< 0.001; 85.4%
Codon 12^b	24	29.1% (26.3% - 32.1%)	< 0.001; 86.2%
Codon 12^c	50	29.0% (26.9% - 31.2%)	< 0.001; 83.9%
Gly12Ala	59	3.3% (2.7% - 3.9%)	< 0.001; 77.8%	< 0.001
Gly12Arg	36	0.9% (0.6% - 1.4%)	< 0.001; 82.9%
Gly12Asp	85	14.6% (13.3% - 16.1%)	< 0.001; 90.8%
Gly12Cys	61	3.5% (3.0% - 4.1%)	< 0.001; 76.1%
Gly12Phe	5	0.2% (0.1% - 0.6%)	0.035; 61.3%
Gly12Ser	62	2.8% (2.2% - 3.6%)	< 0.001; 88.8%
Gly12Val	87	10.2% (9.1% - 11.4%)	< 0.001; 89.6%
Other codon 12	15	0.9% (0.3% - 2.9%)	< 0.001; 96.9%
Codon 13^b	19	9.0% (7.9% - 10.2%)	< 0.001; 62.7%
Codon 13^c	39	8.6% (7.7% - 9.5%)	< 0.001; 55.2%
Gly13Arg	8	0.2% (0.1% - 0.7%)	0.001; 72.0%	< 0.001
Gly13Asp	82	8.6% (7.6% - 9.6%)	< 0.001; 85.0%
Gly13Cys	15	0.7% (0.4% - 1.2%)	< 0.001; 82.7%
Gly13Ser	4	0.3% (0.0% - 4.8%)	< 0.001; 90.9%
Gly13Val	8	0.4% (0.1% - 1.8%)	< 0.001; 80.2%
Exon 3^a	9	2.9% (1.9% - 4.4%)	0.009; 60.9%
Codon 61	14	2.7% (2.1% - 3.5%)	0.001; 62.0%
Gln61Arg	4	0.4% (0.2% - 0.6%)	0.810; 0.0%	0.016
Gln61His	11	1.6% (0.7% - 3.5%)	< 0.001; 92.3%
Gln61Leu	5	0.7% (0.2 %- 2.2%)	0.004; 73.9%
Other codon 61	3	0.2% (0.0% - 1.8%)	< 0.001; 89.3%
Exon 4^a	8	5.0% (4.1% - 6.2%)	0.228; 25.2%
Codon 146	9	2.5% (1.9% - 3.3%)	0.134; 35.5%
P value between exons^d				< 0.001
Sex
Male	55	37.3% (35.1% - 39.7%)	< 0.001; 76.9%	0.011
Female	57	42.2% (39.3% - 45.2%)	< 0.001; 81.7%
Median age of study population
< 62	77	37.0% (34.3% - 39.8%)	< 0.001; 92.6%	0.544
≥ 62	102	36.0% (33.8% - 38.1%)	< 0.001; 90.6%
Meta-regression on median age	179	0.004 (-0.012 - 0.020)	N/A	0.612
Race
< 88% White/Caucasian	21	37.8% (32.4% - 43.4%)	< 0.001; 94.1%	0.401
≥ 88% White/Caucasian	17	34.1% (28.1% - 40.7%)	< 0.001; 91.1%
Study location
Asia	64	31.8% (28.3% - 35.5%)	< 0.001; 93.2%	0.025
Australia	7	27.3% (19.1% - 37.5%)	< 0.001; 97.9%
Europe	146	37.3% (35.2% - 39.3%)	< 0.001; 92.0%
Multi-country	21	39.4% (36.1% - 42.9%)	< 0.001; 88.2%
North America	47	36.4% (33.4% - 39.6%)	< 0.001; 88.9%
South America	3	37.2% (28.7% - 49.9%)	< 0.001; 70.8%
Study design
Observational	226	35.0% (33.5% - 36.6%)	< 0.001; 92.9%	0.004
Clinical trial	62	39.5% (36.9% - 42.1%)	< 0.001; 89.0%
Treatment status
Partial population treated	10	27.5% (18.0% - 39.6%)	< 0.001; 95.0%	0.115
Complete population treated	158	37.2% (35.6% - 38.9%)	< 0.001; 89.6%
Unknown/not treated	120	35.1% (32.9% - 37.4%)	< 0.001; 94.2%
Source
Primary tumor	60	18.9% (15.6% - 22.7%)	< 0.001; 94.6%	0.012
Metastasis	37	21.2% (16.4% - 27.0%)	< 0.001; 94.3%
Both primary tumors and metastases	42	26.5% (23.0% - 30.4%)	< 0.001; 96.4%
Mutation assessment method^e
Gel electrophoresis methods	13	41.1% (35.7% - 46.6%)	0.001; 65.5%
High-resolution melting	18	28.8% (23.7% - 34.6%)	< 0.001; 97.3%
Mass spectrometry	17	36.0% (32.2% - 40.0%)	< 0.001; 92.2%
Multiplex mutation assays	20	36.4% (33.1% - 39.9%)	< 0.001; 87.2%
Mutant allele specific PCR	77	37.4% (35.1% - 39.8%)	< 0.001; 92.2%
Next-generation sequencing	11	29.7% (20.1% - 41.7%)	< 0.001; 97.1%
Pyrosequencing	38	37.2% (33.9% - 40.6%)	< 0.001; 88.9%
Sanger/direct sequencing (PCR)	144	35.5% (34.0% - 37.0%)	< 0.001; 86.3%
Strip assay	7	42.1% (38.9% - 45.3%)	0.045; 53.4%
Other	16	44.0% (37.4% - 50.7%)	< 0.001; 96.3%
Not reported	14	40.3% (33.1% - 47.9%)	< 0.001; 96.1%
Study quality score
≤ 16	172	35.0% (33.1% - 37.0%)	< 0.001; 94.5%	0.073
> 16	116	37.5% (35.7% - 39.3%)	< 0.001; 85.4%
Study time period
Pre-2007	22	35.5% (32.3% - 38.9%)	< 0.001; 63.9%	0.105
Includes 2007	115	36.0% (33.7% - 38.4%)	< 0.001; 90.0%
Post-2007	61	39.3% (36.7% - 42.0%)	< 0.001; 91.5%
Median length of follow-up time
< 25 months	29	34.6% (31.1% - 38.3%)	< 0.001; 80.9%	0.608
≥ 25 months	34	33.0% (28.1% - 38.3%)	< 0.001; 91.7%
Meta-regression on follow-up time	63	0.002 (-0.004 - 0.008)	N/A	0.583

Table 1. Overall Prevalence of KRAS Mutations in mCRC and Subgroups

N studies^f

Summary prevalence (95% CI)

P-Het; I²

P value for heterogeneity within subgroups

^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCodon specified in papers as existing within exon 2; ^cCodon specified in papers as existing within exon 1, exon 2, or unspecified; ^dP values assess differences between global exon estimates only; ^eCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^fIndividual studies may contribute multiple prevalence estimates derived from independent study arms; so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies. mCRC: metastatic colorectal cancer; CI: confidence interval.

Overall

288

35.9% (34.6% - 37.3%)

< 0.001; 92.6%

Exon 1^a

35.5% (30.3% - 41.1%)

< 0.001; 75.4%

Exon 2^a

39.1% (37.1% - 41.3%)

< 0.001; 85.4%

Codon 12^b

29.1% (26.3% - 32.1%)

< 0.001; 86.2%

Codon 12^c

29.0% (26.9% - 31.2%)

< 0.001; 83.9%

Gly12Ala

3.3% (2.7% - 3.9%)

< 0.001; 77.8%

< 0.001

Gly12Arg

0.9% (0.6% - 1.4%)

< 0.001; 82.9%

Gly12Asp

14.6% (13.3% - 16.1%)

< 0.001; 90.8%

Gly12Cys

3.5% (3.0% - 4.1%)

< 0.001; 76.1%

Gly12Phe

0.2% (0.1% - 0.6%)

0.035; 61.3%

Gly12Ser

2.8% (2.2% - 3.6%)

< 0.001; 88.8%

Gly12Val

10.2% (9.1% - 11.4%)

< 0.001; 89.6%

Other codon 12

0.9% (0.3% - 2.9%)

< 0.001; 96.9%

Codon 13^b

9.0% (7.9% - 10.2%)

< 0.001; 62.7%

Codon 13^c

8.6% (7.7% - 9.5%)

< 0.001; 55.2%

Gly13Arg

0.2% (0.1% - 0.7%)

0.001; 72.0%

< 0.001

Gly13Asp

8.6% (7.6% - 9.6%)

< 0.001; 85.0%

Gly13Cys

0.7% (0.4% - 1.2%)

< 0.001; 82.7%

Gly13Ser

0.3% (0.0% - 4.8%)

< 0.001; 90.9%

Gly13Val

0.4% (0.1% - 1.8%)

< 0.001; 80.2%

Exon 3^a

2.9% (1.9% - 4.4%)

0.009; 60.9%

Codon 61

2.7% (2.1% - 3.5%)

0.001; 62.0%

Gln61Arg

0.4% (0.2% - 0.6%)

0.810; 0.0%

0.016

Gln61His

1.6% (0.7% - 3.5%)

< 0.001; 92.3%

Gln61Leu

0.7% (0.2 %- 2.2%)

0.004; 73.9%

Other codon 61

0.2% (0.0% - 1.8%)

< 0.001; 89.3%

Exon 4^a

5.0% (4.1% - 6.2%)

0.228; 25.2%

Codon 146

2.5% (1.9% - 3.3%)

0.134; 35.5%

P value between exons^d

< 0.001

Sex

Male

37.3% (35.1% - 39.7%)

< 0.001; 76.9%

0.011

Female

42.2% (39.3% - 45.2%)

< 0.001; 81.7%

Median age of study population

< 62

37.0% (34.3% - 39.8%)

< 0.001; 92.6%

0.544

≥ 62

102

36.0% (33.8% - 38.1%)

< 0.001; 90.6%

Meta-regression on median age

179

0.004 (-0.012 - 0.020)

N/A

0.612

Race

< 88% White/Caucasian

37.8% (32.4% - 43.4%)

< 0.001; 94.1%

0.401

≥ 88% White/Caucasian

34.1% (28.1% - 40.7%)

< 0.001; 91.1%

Study location

Asia

31.8% (28.3% - 35.5%)

< 0.001; 93.2%

0.025

Australia

27.3% (19.1% - 37.5%)

< 0.001; 97.9%

Europe

146

37.3% (35.2% - 39.3%)

< 0.001; 92.0%

Multi-country

39.4% (36.1% - 42.9%)

< 0.001; 88.2%

North America

36.4% (33.4% - 39.6%)

< 0.001; 88.9%

South America

37.2% (28.7% - 49.9%)

< 0.001; 70.8%

Study design

Observational

226

35.0% (33.5% - 36.6%)

< 0.001; 92.9%

0.004

Clinical trial

39.5% (36.9% - 42.1%)

< 0.001; 89.0%

Treatment status

Partial population treated

27.5% (18.0% - 39.6%)

< 0.001; 95.0%

0.115

Complete population treated

158

37.2% (35.6% - 38.9%)

< 0.001; 89.6%

Unknown/not treated

120

35.1% (32.9% - 37.4%)

< 0.001; 94.2%

Source

Primary tumor

18.9% (15.6% - 22.7%)

< 0.001; 94.6%

0.012

Metastasis

21.2% (16.4% - 27.0%)

< 0.001; 94.3%

Both primary tumors and metastases

26.5% (23.0% - 30.4%)

< 0.001; 96.4%

Mutation assessment method^e

Gel electrophoresis methods

41.1% (35.7% - 46.6%)

0.001; 65.5%

High-resolution melting

28.8% (23.7% - 34.6%)

< 0.001; 97.3%

Mass spectrometry

36.0% (32.2% - 40.0%)

< 0.001; 92.2%

Multiplex mutation assays

36.4% (33.1% - 39.9%)

< 0.001; 87.2%

Mutant allele specific PCR

37.4% (35.1% - 39.8%)

< 0.001; 92.2%

Next-generation sequencing

29.7% (20.1% - 41.7%)

< 0.001; 97.1%

Pyrosequencing

37.2% (33.9% - 40.6%)

< 0.001; 88.9%

Sanger/direct sequencing (PCR)

144

35.5% (34.0% - 37.0%)

< 0.001; 86.3%

Strip assay

42.1% (38.9% - 45.3%)

0.045; 53.4%

Other

44.0% (37.4% - 50.7%)

< 0.001; 96.3%

Not reported

40.3% (33.1% - 47.9%)

< 0.001; 96.1%

Study quality score

≤ 16

172

35.0% (33.1% - 37.0%)

< 0.001; 94.5%

0.073

> 16

116

37.5% (35.7% - 39.3%)

< 0.001; 85.4%

Study time period

Pre-2007

35.5% (32.3% - 38.9%)

< 0.001; 63.9%

0.105

Includes 2007

115

36.0% (33.7% - 38.4%)

< 0.001; 90.0%

Post-2007

39.3% (36.7% - 42.0%)

< 0.001; 91.5%

Median length of follow-up time

< 25 months

34.6% (31.1% - 38.3%)

< 0.001; 80.9%

0.608

≥ 25 months

33.0% (28.1% - 38.3%)

< 0.001; 91.7%

Meta-regression on follow-up time

0.002 (-0.004 - 0.008)

N/A

0.583

**Table 2.** Overall Prevalence of *BRAF* Mutations in mCRC and Subgroups
	N studies^c	Summary prevalence (95% CI)	P-Het; I²	P value for heterogeneity within subgroups
^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^cIndividual studies may contribute multiple prevalence estimates derived from independent study arms, so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies. mCRC: metastatic colorectal cancer; CI: confidence interval.
Overall	142	7.1% (6.5% - 7.8%)	< 0.001; 66.3%
Exon 15^a	44	7.0% (6.1% - 8.1%)	0.001; 45.8%
Val600Glu (V600E)	75	6.8% (5.8% - 7.9%)	< 0.001; 76.9%	0.002
Asp594Gly	4	0.6% (0.1% - 2.8%)	0.064; 58.8%
Sex
Male	12	7.9% (6.5% - 9.7%)	0.076; 39.7%	0.018
Female	12	11.0% (9.2% - 13.1%)	0.260; 18.7%
Median age of study population
< 62	35	7.8% (6.6% - 9.1%)	< 0.001; 55.5%	0.970
≥ 62	57	7.8% (6.7% - 9.1%)	< 0.001; 68.6%
Meta-regression on median age	92	0.012 (-0.014 - 0.036)	N/A	0.390
Race
< 88% White/Caucasian	7	7.1% (5.5% - 9.2%)	0.915; 0.0%	0.855
≥ 88% White/Caucasian	5	7.6% (4.1% - 13.7%)	0.007; 71.7%
Study location
Asia	29	6.0% (5.1% - 7.0%)	0.175; 19.6%	0.002
Australia	7	11.1% (8.6% - 14.2%)	0.062; 49.9%
Europe	79	7.2% (6.3% - 8.1%)	< 0.001; 68.2%
Multi-country	8	8.3% (5.4% - 12.5%)	< 0.001; 83.3%
North America	19	6.6% (5.1% - 8.4%)	0.001; 56.5%
Study design
Observational	114	7.2% (6.5% - 7.9%)	< 0.001; 65.4%	0.897
Clinical trial	28	7.1% (5.7% - 8.7%)	< 0.001; 70.5%
Treatment status
Partial population treated	8	5.9% (3.9% - 8.9%)	0.168; 32.6%	0.659
Complete population treated	76	7.2% (6.3% - 8.3%)	< 0.001; 72.1%
Unknown/not treated	58	7.1% (6.3% - 8.0%)	< 0.001; 57.3%
Source
Primary tumor	34	7.5% (6.3% - 8.7%)	0.152; 20.1%	0.832
Metastasis	16	6.4% (3.8% - 10.6%)	< 0.001; 68.3%
Both primary tumors and metastases	20	7.1% (5.8% - 8.5%)	0.039; 39.0%
Mutation assessment method^b
Gel electrophoresis methods	6	4.5% (2.5% - 7.9%)	0.754; 0.0%
High-resolution melting	13	8.0% (5.9% - 10.9%)	< 0.001; 79.0%
Mass spectrometry	13	5.4% (4.4% - 6.6%)	0.044; 44.2%
Multiplex mutation assays	10	7.5% (5.8% - 9.6%)	0.170; 29.9%
Mutant allele specific PCR	35	8.1% (7.0% - 9.2%)	< 0.001; 57.0%
Next-generation sequencing	6	7.4% (5.7% - 9.5%)	0.974; 0.0%
Not reported	7	7.1% (4.6% - 10.9%)	0.010; 64.2%
Other	6	3.9% (2.3% - 6.4%)	0.004; 71.2%
Pyrosequencing	19	9.1% (7.2% - 11.4%)	< 0.001; 74.3%
Sanger/direct sequencing (PCR)	69	6.8% (6.1% - 7.6%)	0.004; 33.6%
Study quality score
≤ 16	70	7.2% (6.4% - 8.0%)	< 0.001; 58.5%	0.803
> 16	72	7.0% (6.1% - 8.1%)	< 0.001; 70.7%
Study time period
Pre-2007	10	6.3% (4.2% - 9.5%)	0.038; 49.4%	0.520
Includes 2007	59	7.4% (6.2% - 8.7%)	< 0.001; 73.1%
Post-2007	28	6.3% (4.2% - 9.5%)	0.098; 26.7%
Median length of follow-up time
< 25 months	12	9.7% (6.1% - 15.0%)	< 0.001; 71.9%	0.271
≥ 25 months	24	7.4% (6.1% - 8.8%)	0.002; 51.6%
Meta-regression on follow-up time	36	-0.005 (-0.015; 0.005)	N/A	0.314

Table 2. Overall Prevalence of BRAF Mutations in mCRC and Subgroups

N studies^c

Summary prevalence (95% CI)

P-Het; I²

P value for heterogeneity within subgroups

^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^cIndividual studies may contribute multiple prevalence estimates derived from independent study arms, so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies. mCRC: metastatic colorectal cancer; CI: confidence interval.

Overall

142

7.1% (6.5% - 7.8%)

< 0.001; 66.3%

Exon 15^a

7.0% (6.1% - 8.1%)

0.001; 45.8%

Val600Glu (V600E)

6.8% (5.8% - 7.9%)

< 0.001; 76.9%

0.002

Asp594Gly

0.6% (0.1% - 2.8%)

0.064; 58.8%

Sex

Male

7.9% (6.5% - 9.7%)

0.076; 39.7%

0.018

Female

11.0% (9.2% - 13.1%)

0.260; 18.7%

Median age of study population

< 62

7.8% (6.6% - 9.1%)

< 0.001; 55.5%

0.970

≥ 62

7.8% (6.7% - 9.1%)

< 0.001; 68.6%

Meta-regression on median age

0.012 (-0.014 - 0.036)

N/A

0.390

Race

< 88% White/Caucasian

7.1% (5.5% - 9.2%)

0.915; 0.0%

0.855

≥ 88% White/Caucasian

7.6% (4.1% - 13.7%)

0.007; 71.7%

Study location

Asia

6.0% (5.1% - 7.0%)

0.175; 19.6%

0.002

Australia

11.1% (8.6% - 14.2%)

0.062; 49.9%

Europe

7.2% (6.3% - 8.1%)

< 0.001; 68.2%

Multi-country

8.3% (5.4% - 12.5%)

< 0.001; 83.3%

North America

6.6% (5.1% - 8.4%)

0.001; 56.5%

Study design

Observational

114

7.2% (6.5% - 7.9%)

< 0.001; 65.4%

0.897

Clinical trial

7.1% (5.7% - 8.7%)

< 0.001; 70.5%

Treatment status

Partial population treated

5.9% (3.9% - 8.9%)

0.168; 32.6%

0.659

Complete population treated

7.2% (6.3% - 8.3%)

< 0.001; 72.1%

Unknown/not treated

7.1% (6.3% - 8.0%)

< 0.001; 57.3%

Source

Primary tumor

7.5% (6.3% - 8.7%)

0.152; 20.1%

0.832

Metastasis

6.4% (3.8% - 10.6%)

< 0.001; 68.3%

Both primary tumors and metastases

7.1% (5.8% - 8.5%)

0.039; 39.0%

Mutation assessment method^b

Gel electrophoresis methods

4.5% (2.5% - 7.9%)

0.754; 0.0%

High-resolution melting

8.0% (5.9% - 10.9%)

< 0.001; 79.0%

Mass spectrometry

5.4% (4.4% - 6.6%)

0.044; 44.2%

Multiplex mutation assays

7.5% (5.8% - 9.6%)

0.170; 29.9%

Mutant allele specific PCR

8.1% (7.0% - 9.2%)

< 0.001; 57.0%

Next-generation sequencing

7.4% (5.7% - 9.5%)

0.974; 0.0%

Not reported

7.1% (4.6% - 10.9%)

0.010; 64.2%

Other

3.9% (2.3% - 6.4%)

0.004; 71.2%

Pyrosequencing

9.1% (7.2% - 11.4%)

< 0.001; 74.3%

Sanger/direct sequencing (PCR)

6.8% (6.1% - 7.6%)

0.004; 33.6%

Study quality score

≤ 16

7.2% (6.4% - 8.0%)

< 0.001; 58.5%

0.803

> 16

7.0% (6.1% - 8.1%)

< 0.001; 70.7%

Study time period

Pre-2007

6.3% (4.2% - 9.5%)

0.038; 49.4%

0.520

Includes 2007

7.4% (6.2% - 8.7%)

< 0.001; 73.1%

Post-2007

6.3% (4.2% - 9.5%)

0.098; 26.7%

Median length of follow-up time

< 25 months

9.7% (6.1% - 15.0%)

< 0.001; 71.9%

0.271

≥ 25 months

7.4% (6.1% - 8.8%)

0.002; 51.6%

Meta-regression on follow-up time

-0.005 (-0.015; 0.005)

N/A

0.314

**Table 3.** Overall Prevalence of *NRAS* Mutations in mCRC and Subgroups
	N Studies^e	Summary prevalence (95% CI)	P-Het; I²	P value for heterogeneity within subgroups
^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCodon specified in papers as existing within exon 1, exon 2, exon 3 or unspecified; ^cP values assess differences between global exon estimates only; ^dCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^eIndividual studies may contribute multiple prevalence estimates derived from independent study arms, so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies; ^fP value assesses differences between codon estimates. *N < 3, insufficient studies to run a meta-analysis. mCRC: metastatic colorectal cancer; CI: confidence interval.
Overall	49	4.1% (3.5% - 4.8%)	< 0.001; 56.0%
Exon 2^a	6	2.3% (1.4% - 3.7%)	0.127; 41.8%
Codon 12^b	7	2.2% (1.6% - 3.0%)	0.209; 28.7%	< 0.001^f
Codon 13^b	4	0.7% (0.5% - 1.0%)	0.927; 0.0%
Exon 3^a	5	2.4% (1.1% - 5.0%)	0.003; 75.5%
Codon 61^b	10	3.6% (2.6% - 5.0%)	0.065; 44.1%
Exon 4^a	3	0.6% (0.1% - 3.9%)	0.991; 0.0%
P value between exons^c				0.368
Sex
Male	*	*	*	*
Female	*	*	*
Median age of study population
< 62	12	3.7% (3.0% - 4.7%)	0.863; 0.0%	0.479
≥ 62	12	4.3% (3.2% - 5.6%)	0.036; 47.1%
Meta-regression on median age	24	0.006 (-0.048 - 0.060)	N/A	0.822
Race
< 88% White/Caucasian	*	*	*	*
≥ 88% White/Caucasian	3	5.8% (3.4% - 9.8%)	0.954; 0.0%
Study location
Asia	13	3.0% (2.0% - 4.5%)	0.009; 54.5%	0.108
Australia	*	*	*
Europe	22	4.6% (3.7% - 5.8%)	< 0.001; 64.6%
Multi-country	3	5.8% (3.4% - 9.8%)	0.954; 0.0%
North America	10	3.6% (2.9% - 4.5%)	0.980; 0.0%
Study design
Observational	39	3.9% (3.3% - 4.7%)	< 0.001; 61.9%	0.105
Clinical trial	10	5.3% (3.9% - 7.1%)	0.544; 0.0%
Treatment status
Partial population treated	5	3.5% (2.1% - 6.0%)	0.940; 0.0%	0.840
Complete population treated	15	4.2% (3.3% - 5.3%)	0.336; 10.5%
Unknown/not treated	29	4.1% (3.3% - 5.0%)	< 0.001; 69.5%
Source
Primary tumor	8	3.4% (2.4% - 4.8%)	0.026; 55.9%	0.318
Metastasis	6	4.9% (3.4% - 7.0%)	0.936; 0.0%
Both primary tumors and metastases	9	3.5% (2.5% - 4.9%)	0.019; 56.3%
Mutation assessment method^d
High-resolution melting	6	3.0% (1.7% - 5.1%)	< 0.001; 84.6%
Mass spectrometry	11	4.0% (3.2% - 5.0%)	0.023; 51.8%
Multiplex mutation assays	4	4.2% (3.3% - 5.4%)	0.233; 29.8%
Mutant allele specific PCR	7	4.3% (3.4% - 5.3%)	0.253; 23.1%
Next-generation sequencing	8	4.9% (3.9% - 6.2%)	0.309; 15.4%
Other	3	4.5% (2.6% - 7.6%)	0.064; 63.6%
Pyrosequencing	9	5.1% (3.6% - 7.3%)	< 0.001; 72.4%
Sanger/direct sequencing (PCR)	20	4.5% (4.0% - 5.0%)	0.483; 0.0%
Strip assay	*	*	*
Study quality score
≤ 16	29	3.8% (3.0% - 4.8%)	< 0.001; 69.0%	0.151
> 16	20	4.7% (4.0% - 5.5%)	0.535; 0.0%
Study time period
Pre-2007	*	*	*
Includes 2007	9	3.7% (2.9% - 4.7%)	0.447; 0.0%	0.247
Post-2007	26	4.5% (3.6% - 5.6%)	< 0.001; 63.2%
Median length of follow-up time
< 25 months	*	*	*	*
≥ 25 months	7	4.1% (3.0% - 5.5%)	0.998; 0.0%
Meta-regression on follow-up time		0.000 (-0.012 - 0.012)	N/A	0.957

Table 3. Overall Prevalence of NRAS Mutations in mCRC and Subgroups

N Studies^e

Summary prevalence (95% CI)

P-Het; I²

P value for heterogeneity within subgroups

^aGlobal exon estimate (most global estimate for a given exon contained within a manuscript); ^bCodon specified in papers as existing within exon 1, exon 2, exon 3 or unspecified; ^cP values assess differences between global exon estimates only; ^dCategories not mutually exclusive as some studies used multiple forms of mutation assessment methods, P value not calculated; ^eIndividual studies may contribute multiple prevalence estimates derived from independent study arms, so N refers to the number of independent prevalence estimates included in summary measure and may exceed the actual number of studies; ^fP value assesses differences between codon estimates. *N < 3, insufficient studies to run a meta-analysis. mCRC: metastatic colorectal cancer; CI: confidence interval.

Overall

4.1% (3.5% - 4.8%)

< 0.001; 56.0%

Exon 2^a

2.3% (1.4% - 3.7%)

0.127; 41.8%

Codon 12^b

2.2% (1.6% - 3.0%)

0.209; 28.7%

< 0.001^f

Codon 13^b

0.7% (0.5% - 1.0%)

0.927; 0.0%

Exon 3^a

2.4% (1.1% - 5.0%)

0.003; 75.5%

Codon 61^b

3.6% (2.6% - 5.0%)

0.065; 44.1%

Exon 4^a

0.6% (0.1% - 3.9%)

0.991; 0.0%

P value between exons^c

0.368

Sex

Male

Female

Median age of study population

< 62

3.7% (3.0% - 4.7%)

0.863; 0.0%

0.479

≥ 62

4.3% (3.2% - 5.6%)

0.036; 47.1%

Meta-regression on median age

0.006 (-0.048 - 0.060)

N/A

0.822

Race

< 88% White/Caucasian

≥ 88% White/Caucasian

5.8% (3.4% - 9.8%)

0.954; 0.0%

Study location

Asia

3.0% (2.0% - 4.5%)

0.009; 54.5%

0.108

Australia

Europe

4.6% (3.7% - 5.8%)

< 0.001; 64.6%

Multi-country

5.8% (3.4% - 9.8%)

0.954; 0.0%

North America

3.6% (2.9% - 4.5%)

0.980; 0.0%

Study design

Observational

3.9% (3.3% - 4.7%)

< 0.001; 61.9%

0.105

Clinical trial

5.3% (3.9% - 7.1%)

0.544; 0.0%

Treatment status

Partial population treated

3.5% (2.1% - 6.0%)

0.940; 0.0%

0.840

Complete population treated

4.2% (3.3% - 5.3%)

0.336; 10.5%

Unknown/not treated

4.1% (3.3% - 5.0%)

< 0.001; 69.5%

Source

Primary tumor

3.4% (2.4% - 4.8%)

0.026; 55.9%

0.318

Metastasis

4.9% (3.4% - 7.0%)

0.936; 0.0%

Both primary tumors and metastases

3.5% (2.5% - 4.9%)

0.019; 56.3%

Mutation assessment method^d

High-resolution melting

3.0% (1.7% - 5.1%)

< 0.001; 84.6%

Mass spectrometry

4.0% (3.2% - 5.0%)

0.023; 51.8%

Multiplex mutation assays

4.2% (3.3% - 5.4%)

0.233; 29.8%

Mutant allele specific PCR

4.3% (3.4% - 5.3%)

0.253; 23.1%

Next-generation sequencing

4.9% (3.9% - 6.2%)

0.309; 15.4%

Other

4.5% (2.6% - 7.6%)

0.064; 63.6%

Pyrosequencing

5.1% (3.6% - 7.3%)

< 0.001; 72.4%

Sanger/direct sequencing (PCR)

4.5% (4.0% - 5.0%)

0.483; 0.0%

Strip assay

Study quality score

≤ 16

3.8% (3.0% - 4.8%)

< 0.001; 69.0%

0.151

> 16

4.7% (4.0% - 5.5%)

0.535; 0.0%

Study time period

Pre-2007

Includes 2007

3.7% (2.9% - 4.7%)

0.447; 0.0%

0.247

Post-2007

4.5% (3.6% - 5.6%)

< 0.001; 63.2%

Median length of follow-up time

< 25 months

≥ 25 months

4.1% (3.0% - 5.5%)

0.998; 0.0%

Meta-regression on follow-up time

0.000 (-0.012 - 0.012)

N/A

0.957

**Table 4.** Hazard Ratios and Median Overall and Progression-Free Survival by Mutation Status
	Overall survival	Progression-free survival
*N < 3 (studies), insufficient for meta-analysis. mCRC: metastatic colorectal cancer; HR: hazard ratio; CI: confidence interval.
Survival analysis (mutant vs. wild-type)
KRAS	47	1.49 (1.37 - 1.64)	< 0.001; 50.2%	25	1.62 (1.33 - 1.97)	< 0.001; 83.1%
BRAF	32	2.83 (2.23 - 3.58)	< 0.001; 84.1%	12	2.90 (1.84 - 4.56)	< 0.001; 91.3%
NRAS	4	1.88 (1.35 - 2.62)	0.795; 0.0%	*	*	*
Median survival		Median months (95% CI)			Median months (95% CI)
KRAS mutant	41	13.41 (11.35 - 15.83)	< 0.001; 96.8%	42	4.48 (3.58 - 5.62)	< 0.001; 99.2%
KRAS wild-type	42	17.00 (14.52 - 19.89)	< 0.001; 96.8%	49	5.98 (4.74 - 7.54)	< 0.001; 99.3%
P value for difference	0.022	0.04
BRAF mutant	12	8.71 (6.54 - 11.59)	< 0.001; 90.1%	11	5.05 (3.67 - 6.96)	< 0.001; 88.6%
BRAF wild-type	13	17.19 (13.00 - 22.74)	< 0.001; 96.6%	12	8.26 (6.78 - 10.07)	< 0.001; 93.5%
P value for difference	< 0.001	0.005

Table 4. Hazard Ratios and Median Overall and Progression-Free Survival by Mutation Status

Overall survival

Progression-free survival

N studies

HR (95% CI)

P-Het; I²

N studies

HR (95% CI)

P-Het; I²

*N < 3 (studies), insufficient for meta-analysis. mCRC: metastatic colorectal cancer; HR: hazard ratio; CI: confidence interval.

Survival analysis (mutant vs. wild-type)

KRAS

1.49 (1.37 - 1.64)

< 0.001; 50.2%

1.62 (1.33 - 1.97)

< 0.001; 83.1%

BRAF

2.83 (2.23 - 3.58)

< 0.001; 84.1%

2.90 (1.84 - 4.56)

< 0.001; 91.3%

NRAS

1.88 (1.35 - 2.62)

0.795; 0.0%

Median survival

Median months (95% CI)

KRAS mutant

13.41 (11.35 - 15.83)

< 0.001; 96.8%

4.48 (3.58 - 5.62)

< 0.001; 99.2%

KRAS wild-type

17.00 (14.52 - 19.89)

< 0.001; 96.8%

5.98 (4.74 - 7.54)

< 0.001; 99.3%

P value for difference

0.022

0.04

BRAF mutant

8.71 (6.54 - 11.59)

< 0.001; 90.1%

5.05 (3.67 - 6.96)

< 0.001; 88.6%

BRAF wild-type

17.19 (13.00 - 22.74)

< 0.001; 96.6%

8.26 (6.78 - 10.07)

< 0.001; 93.5%

P value for difference

< 0.001

0.005