Indian Journal of Cancer
Home  ICS  Feedback Subscribe Top cited articles Login 
Users Online :1991
Small font sizeDefault font sizeIncrease font size
Navigate here
  Search
 
  
Resource links
 »  Similar in PUBMED
 »  Search Pubmed for
 »  Search in Google Scholar for
 »Related articles
 »  Article in PDF (340 KB)
 »  Citation Manager
 »  Access Statistics
 »  Reader Comments
 »  Email Alert *
 »  Add to My List *
* Registration required (free)  

 
  In this article
 »  Abstract
 » Introduction
 »  Materials and Me...
 » Results
 » Discussion
 » Conclusion
 » Acknowledgments
 »  References
 »  Article Tables

 Article Access Statistics
    Viewed1816    
    Printed48    
    Emailed0    
    PDF Downloaded295    
    Comments [Add]    

Recommend this journal

 


 
  Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 51  |  Issue : 4  |  Page : 531-537
 

Prevalence of KRAS mutations in metastatic colorectal cancer: A retrospective observational study from India


1 Department of Molecular Pathology, Triesta Reference Laboratory, Triesta Sciences, A unit of Healthcare Global Enterprises Ltd., Bengaluru, Karnataka, India
2 Center for Academics and Research, HCG Foundation, Bengaluru, Karnataka, India
3 Department of Surgical Oncology, HCG cancer hospitals, Bengaluru, Karnataka, India
4 Department of Medical Oncology, HCG cancer hospitals, Bengaluru, Karnataka, India
5 Health Care Global Enterprises Ltd., Bengaluru, Karnataka, India

Date of Web Publication1-Feb-2016

Correspondence Address:
V H Veldore
Department of Molecular Pathology, Triesta Reference Laboratory, Triesta Sciences, A unit of Healthcare Global Enterprises Ltd., Bengaluru, Karnataka
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0019-509X.175371

Rights and Permissions

 » Abstract 

Background: One of the genetic alterations implicated in tumor progression in colorectal cancers (CRCs) are abnormalities in Kristen Rat Sarcoma (KRAS) gene. Evaluation of KRAS mutation status is an important prognostic factor and has predictive value in deciding first line therapy based on monoclonal antibodies such as Cetuximab and Panitumumab in metastatic CRCs. Materials And Methods: In this retrospective study, we analyzed 7 different somatic mutations in Exon 2 of KRAS gene in 299 unselected incidental CRC patients who visited the hospital for clinical management during the period 2009–2013. Most of the tumors were primarily originating from colon and rectum; nevertheless, there were a few from rectosigmoid, sigmoid, ceacum and anal canal in the study group. Genomic DNA extracted from paraffin embedded tumor tissues was screened for 7 point mutations located in Codons 12 and 13 of KRAS gene, using Scorpions amplified refractory mutation system real time polymerase chain reaction technology. Statistical analysis was performed to assess bivariate relationship between different variables that includes: mutation status, mutation type, tumor location, tumor morphology, age and sex. Results: Prevalence of mutation in Codons 12 and 13 was 42.8% in the study group. Well-differentiated tumors had significantly more mutation positivity than moderately and poorly differentiated tumors (P = 0.001). 92% of the mutations were from Codon 12 and 8% in Codon 13. Glycine to Arginine was relatively more common in rectosigmoid followed by ceacum, while Glycine to Alanine mutation was relatively more prevalent in sigmoid, followed by rectum and rectosigmoid. CONCLUSION: The results suggest a prevalence of KRAS mutation at 42.8% in Indian population indicating that this testing is very crucial for targeted therapy management in metastatic CRC in India. Further analysis on mutation status of other homologues such as NRAS and downstream partner, v-raf murine sarcoma viral oncogene homolog B1, would add value to understanding the role of anti-epidermal growth factor receptor therapy in CRC management.


Keywords: Codon 12, Codon 13, epidermal growth factor receptor, KRAS mutation, metastatic Colorectal Cancer, Scorpion ARMS Realtime PCR, tyrosine kinase inhibitor


How to cite this article:
Veldore V H, Rao M R, Prabhudesai S A, Tejaswi R, Kakara S, Pattanayak S, Krishnamoorthy N, Tejaswini B N, Hazarika D, Gangoli A, Rahman S M, Dixit J, Naik R, Diwakar R B, Satheesh C T, Shashidhara H P, Patil S, Gopinath K S, Kumar B S. Prevalence of KRAS mutations in metastatic colorectal cancer: A retrospective observational study from India. Indian J Cancer 2014;51:531-7

How to cite this URL:
Veldore V H, Rao M R, Prabhudesai S A, Tejaswi R, Kakara S, Pattanayak S, Krishnamoorthy N, Tejaswini B N, Hazarika D, Gangoli A, Rahman S M, Dixit J, Naik R, Diwakar R B, Satheesh C T, Shashidhara H P, Patil S, Gopinath K S, Kumar B S. Prevalence of KRAS mutations in metastatic colorectal cancer: A retrospective observational study from India. Indian J Cancer [serial online] 2014 [cited 2019 Aug 22];51:531-7. Available from: http://www.indianjcancer.com/text.asp?2014/51/4/531/175371



 » Introduction Top


Colorectal cancer (CRC) is the third most common cancer (1.36 million new cases, 10.0% of all cancers) worldwide as per the global cancer statistics GLOBOCAN 2012[1] and is the fourth most common cause of mortality associated with cancer. The incidence of CRC is lower in Asian/Indian population as compared to the western world; nevertheless, it has been increasing at an alarming rate due to several interacting factors including the life style, dietary habits and inherent genetic makeup.[2] As per global cancer atlas the age standardized incidence rates was 20.6 and 14.3 for men and women respectively per one lakh population.[3] As per the National cancer registry records dated 2005, estimated age-adjusted standardized rates of CRC in India is 4.2 and 3.2/100,000 for males and females, respectively as compared to 35.3 and 25.7, respectively, in the USA.[4],[5]

RAS mutations and colorectal cancer management

Genetic alterations in epidermal growth factor receptor (EGFR) family of receptors and their downstream phosphor-relay members has been well documented as major triggering events for the carcinogenesis and progression in several tumors.[6],[7] The epidermal growth factor (EGF) binds to its receptor, EGFR and initiates a cascade of signaling events and the Kristen Rat Sarcoma (KRAS) enzyme is a key component to these molecular interactions. However, certain oncogenic somatic mutations in the KRAS gene makes the enzyme constitutively active to function whether or not it receives the driving signal from EGFR. Thereby, in mutated KRAS tumors, the inhibition of EGFR by Cetuximab does not block the downstream molecular events that are activated further down the cascade. In July 2009, the US Food and Drug Administration (FDA) approved EGFR-targeted Monoclonal Antibody (Mab) therapy with Cetuximab (Erbitux), and Panitumumab (Vectibix) in patients with metastatic CRC along with analysis of KRAS mutation status, which is predictive biological marker of resistance.[8],[9],[10],[11],[12]

Constitutive activation of KRAS proto-oncogene by point mutations in Codons 12 and 13 has been well documented in several studies, and these mutational hotspots constitute 90% of the Ras mutations in CRC. Results from the correlation with clinical response suggested mutations in the codon 12 and codon 13 of KRAS in the Exon 2 are predominant, and known to be bad responders to Mab therapy.[13],[14],[15],[16],[17],[18],[19],[20],[21] These mutations lead to constitutive activation of KRAS protein, with the molecule remaining in the "ON" state indefinitely thus promoting the cell proliferation negating the effect of Mab binding to EGF receptor on the cancer cells. KRAS is a 21.6 kDa membrane-associated protein that belongs to the superfamily of small GTPases. KRAS, NRAS and HRAS are proto-oncogenes of this Ras family and are known to be mutated in several cancers at 80%, 15% and 5% respectively.[22] RAS wild-type status predicts survival and is associated with early radiological response in metastatic CRC treated with Cetuximab.[23] Frequency of KRAS mutations observed varies between 30% and 60% in CRCs from different studies.[24],[25],[26],[27],[28],[29],[30],[31],[32] The concordance between KRAS mutations in the primary tumor and related metastatic sites is high.[33] As per the latest National Comprehensive Cancer Network (NCCN) guidelines, evaluation of RAS mutation status that include KRAS + NRAS is part of the diagnostic work up for treatment of metastatic CRCs (NCCN V.2 2015).[34],[35]

Dietary factors, life style, and other environmental factors are also known to influence acquired mutations in KRAS genes that are known to be critical DNA targets for chemical carcinogens. KRAS mutations are known to be an early event in several other neoplasms such as lung and pancreas. Although intake of cruciferous vegetables, dietary folate, animal protein and fat, Vitamins B6 and B12 are known be associated with KRAS mutations in CRCs,[36] there are exceptions to this association and furthermore these correlations have not been proven to be significant and consistent. In the Indian scenario, we see a large portion of men being affected than women with CRC. In the current study, we have investigated the molecular epidemiology, clinic-pathological features and prognostic impact of KRAS gene mutation in Codon 12 and Codon 13 in CRC patients from our institution using a highly sensitive method for the detection of somatic mutations: Scorpions amplified refractory mutation system (ARMS) real-time polymerase chain reaction/THERASCREEN KRAS mutation detection system.[37] This is a prevalence study that summarizes the retrospective analysis on metastatic CRC patients who visited our hospital and underwent KRAS mutation screening as per the guidelines during the period 2009–2013.

Detection and analysis of KRAS mutations in the initial diagnostic workup would exclude a significant proportion of patients with CRC from being offered therapeutically ineffectual anti-EGFR Mab therapy in KRAS mutated patients, thereby helping reduce the treatment costs of cancer management.


 » Materials and Methods Top


In the present retrospective study, CRC patients who visited our hospital during the period 2009–2013 were analyzed for histopathology and KRAS mutation. In all the 299 patients, the relationship between different clinicopathological variables was analyzed retrospectively with mutation status using statistical methods.

DNA extraction

Genomic DNA was extracted from formalin-fixed paraffin embedded (FFPE) tumor tissues. The criteria being a minimum of 10% tumor cells, and 2 × 20 µ section was taken for all DNA extractions and were processed using QIAamp DNA mini kit (Cat. No: 51306) (Methodology as described in the kit insert).

DNA quantification

The DNA was quantified using Nano drop spectrophotometer for relative absorbance ratio at 260, 280 and 230 nm. Subsequently, the quality of the DNA was assessed by reatlime PCR methods as described by the manufacturer (DxS/THERASCREEN KRAS PCR kit, Qiagen).

Real-time polymerase chain reaction

Mutations in Codons 12 and 13 of Exon 2 in the KRAS oncogene were analyzed using THERASCREEN KRAS PCR kit from QIAGEN Inc (earlier DxS diagnostics Ltd) based on Scorpions ARMS technology on an ABI 7000 (Applied Biosystems Inc) and Light Cycler ® 480 platforms. The kit has primers designed for detection of 7 SNPs/mutations which are most commonly observed in CRCs and was cleared by US FDA in the year 2012, as an approved genetic test for KRAS testing to decide Mab treatment in metastatic Colorectal Cancer (mCRC). Analysis was carried out for all the samples as described in the kit procedure. The Scorpions technology in combination with ARMS methodology has been shown to detect somatic mutations with much higher sensitivity than many other conventional sequencing based techniques. This technology is known to detect 1% of the mutations in the background of the wild-type gene signature as described in the technical literature of the KRAS PCR kit [37]. Patients were considered to be positive for the KRAS mutation even if one out of seven mutations was detected.

Statistical analysis

The data were analyzed using SPSS version 20 for windows (SPSS Inc). Mutations were categorized as positive or negative qualitatively and assessed using Chi-square test for proportions across gender, age and clinical parameters such as tumor grade, tumor origin/surgically resected region, mutation status and mutation subtype as categories. The total number of mutations in Codons 12 and 13 were analyzed and assessed across gender, age and histological differentiation and site of the tumor using Pearsons Chi-square test.


 » Results Top


A total of 299 patients with CRC were analyzed for KRAS mutation. The mean age of the population was 55.9 ± 12.8 years. The majority of patients were male (65.2%), and those had well-differentiated adenocarcinoma predominantly (79.9%), and lesions were located primarily in the colon (48.5%). The mutation was present in 42.8% of the study population. Mutations in Codon 12: Glycine (Gly) to Valine (Val) was more followed by Glycine (Gly) to Cysteine (Cys) and then Glycine (Gly) to Aspartate (Asp). Mutation in Codon 13: Glycine to Aspartate was 8% [Table 1].{Table 1}

Histopathology type and KRAS mutation

In well differentiated adenocarcinoma, there was a significantly increased mutation in Gly to Val (χ2 = 12.9, P = 0.002), Gly to Cys (χ2 = 8.04, P = 0.02) and Gly to Ser (χ2 = 3.90, P = 0.05) as compared to moderately and poorly differentiated tumors. Overall KRAS mutation was also significantly higher (χ2 = 14.9, P = 0.001) in well differentiated adenocarcinoma compared to other tumor subtypes [Table 2].
Table 1: Clinical characteristics and mutation prevalence in patients with colorectal cancer

Click here to view


Location of tumor and clustering of mutation subtype in KRAS Codon 12

Gly to Arg mutation was significantly high in rectosigmoid and ceacum (χ2 = 9.80, P = 0.04). Gly to Ala mutation was significantly high in sigmoid, rectum and rectosigmoid colon (χ2 = 13.8, P = 0.008) [Table 3].
Table 3: Comparison of mutation across different sites in colon and rectum

Click here to view


Number of mutations versus histopathology types

There was a significantly increased representation of mutation percentage in well-differentiated tumors compared to moderate and poorly differentiated tumors (χ2 = 4.14, P = 0.04). Similarly, two or more mutations were found more frequently in the former compared to latter subtype tumors [Table 4].
Table 4: Comparison of number of Mutations with histopathology type

Click here to view


Mutation number versus location of tumor

There was a significant increase in number of mutations in rectum, recto-sigmoid, sigmoid colon and ceacum (χ2 = 16.6, P = 0.03) indicating that mutations occurred more at distal end as well as the extreme proximal of the colon [Table 5].
Table 5: Comparison of number of mutations with site of tumor

Click here to view


Neither sex nor age tends to influence mutation subtypes in Codon 12 and 13 which has been different across populations.[24],[25],[26],[27],[28],[29],[30],[31],[32] As the median age of the study sample was 56 years, approximately half of them in each group above and below this cut-off had mutation positivity indicating that age had no influence on mutation status. When 40 years was considered as cut-off age as the literature suggests more aggressive phenotype with mutation below 40 years,[38] in our study subset, the mutation positivity did not change significantly. Gender did not seem to influence the mutation positivity of the study cohort though females tend to have a greater percent of mutation positivity. This was also the same with treatment status with less number of patients having received chemotherapy and radiation before the tumor excision. There was a tendency for more mutation in the sigmoid, rectum and recto sigmoid colon as compared to other sites. There were no significant effects of age, sex, treatment status, metastasis and site of malignancy on mutation positivity based on Chi-square test.


 » Discussion Top


The results from our study suggest that both gender and age category did not seem to influence mutation status. The mutation was present in 42.8% of the study population. Mutations in Codon 12: Glycine (Gly) to Valine (Val) was more followed by Glycine (Gly) to Cysteine (Cys), Glycine (Gly) to Aspartate (Asp), Glycine (Gly) to Alanine (Ala), Glycine (Gly) to Serine (Ser) and Glycine (Gly) to Arginine (Arg). Our results are similar to earlier studies that have shown similar prevalence rates and mutation to occur independently of the influence of age or gender.[24],[25],[26],[27],[28],[29],[30],[31],[32] However, mutation rates were more in the distal end of the colon in rectosigmoid and rectum, and well-differentiated tumors compared to poorly differentiated tumors.

Mutant KRAS alleles are detected in the background of wild-type genomic DNA from the tumor tissue in a Real-time PCR platform based on Scorpions ARMS technology. This method being highly selective in detecting 1% of the mutant gene on the background of wild-type allele, it is considered to be much more sensitive than the conventional dye terminator sequencing and has been well documented from various studies [39],[40] as well as from a recent report from our laboratory.[41] As observed in many different studies [24],[25],[26],[27],[28],[29],[30],[31],[32] the G > A transition that is a mutation of Gly at codon 12 to Asp was not the most predominant mutation. We observed Gly to Val (G > T) transition at codon 12 as the most common mutation in our study subset. One such report that demonstrated high preponderance of Gly to Val was from a subset of Iraqi patients.[42] The genetic alterations occurred significantly more frequently in tumors of the left side of the colon as compared to the right side of the colon, in contrast to other reports which show a right sided shift.[43],[44] Similar pattern, as observed in our study for mutational preference in KRAS, was earlier observed in a multicentric study on molecular screening in 1093 colorectal adenomas [45] and also from a study reported on Turkish CRC patients [46], thus indicating a difference in the biological behavior. As there is very little information on KRAS mutation and its correlation to various ethnicities, this observation needs further studies to understand the molecular alterations in the Indian context. Additional factors that could be contributed to this pattern are lifestyle changes such as sedentary habits, fewer fibers or roughage in food, bowel motility disorders and chronic constipation. Constipation exposes the bowel lining to toxins released by fecal bacteria and undigested food that may cause tissue injury.[47] This may also explain a higher prevalence of mutations in distal colon and rectum. The mutation of the codon 13 appeared more frequently in the cases of local recurrences. There were four patients who had triple mutants. Patients with tumors containing double and triple mutants had solitary lung and liver metastases. Molecular alterations accumulated in a pattern with double/triple positive cases indicate varying degree of genetic heterogeneity.

This study demonstrates that abnormalities of KRAS gene is an important findings in colorectal neoplasias in Indian population, the data correlate with KRAS mutation prevalence from global studies [48],[49] as well as independent reports from different countries/continents such as Australia: 39%,[50] Japan: 33.5%,[51] Europe 38.5%,[52] USA 31%,[53] Spain 44%,[54] Netherlands 37%,[55] China (40.4%)[56] and other studies from India.[57],[58],[59] Reason for the variation of KRAS mutation prevalence possibly could be genetic, and/or method of detection and sample type. To the best of our knowledge, this report is the first largest subset representation from India to show the KRAS mutation prevalence using a highly sensitive and FDA approved method. The advantage of using such robust methodologies not only reduces the chances of false negativity but also improves the turnaround time (TAT)/turnover time of these tests from 12 to 15 working days to 3–4 working days. However, variations in the mutation frequencies with similar studies from different parts of India [57],[58],[59] cannot be rule out and could be attributed to factors, such as sample size, cohort selection, FFPE tissue samples, methods of mutation detection. The treatment solely on the basis of KRAS status is not ideal due to the fact that there are some nonresponders among the Wild type-KRAS patients, which could be attributed to some extent to mutations in its closest homologue NRAS and downstream target BRAF (v-raf murine sarcoma viral oncogene homolog B1). Despite recent changes and developments in the clinical management of metastatic CRC,[34],[35] KRAS mutation remains one of the most recognized molecular predictive markers in mCRC, predicting the efficacy of anti-EGFR antibodies. Sensitive methodology, technology, appropriate sample selection, and sample type, would certainly play an important role in increasing the success rate in a given population for anti-EGFR treatment in mCRC. There has been a significant increase in 5 years survival in metastatic CRC over the past decade, from 10% to 65%,[38] despite more than 55% of patients presenting with lymph node or distant metastases. This increase in 5 years survival is well correlated with targeted therapy that again depends on the molecular diagnosis of the disease further confirms the influence of these mutations in CRC management outcomes.


 » Conclusion Top


Prevalence of KRAS mutation (42.8%) in India is at par with world literature that varies from 30% to 60%. The development and practical use of ARMS or more sensitive molecular diagnostic methods hopefully will gain more importance in future for selection of most eligible patients for EGFR based targeted therapy. Furthermore, extended RAS testing beyond KRAS would add value to the subset of Wild-type KRAS patients who could get the benefit of targeted therapy. Considering the percentage of RAS mutation status, further studies are warranted to address the role of diet and life style with the incidence of CRC in this region.


 » Acknowledgments Top


The study has been internally supported by the institution.

 
 » References Top

1.
Ferlay J, Soerjomataram I, Dikshit R, Eser S, Mathers C, Rebelo M, et al. Cancer incidence and mortality worldwide: Sources, methods and major patterns in GLOBOCAN 2012. Int J Cancer 2015; 136:E359-86.  Back to cited text no. 1
    
2.
Sung JJ, Lau JY, Goh KL, Leung WK, Asia Pacific Working Group on Colorectal Cancer. Increasing incidence of colorectal cancer in Asia: Implications for screening. Lancet Oncol 2005; 6:871-6.  Back to cited text no. 2
    
3.
Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin 2011; 61:69-90.  Back to cited text no. 3
    
4.
Mateka JL, Haniff MM, Bainey RS, Iliou CB. Interesting trends in incidence and mortality rates of colorectal cancer in the United States of America. J Gastrointest Dig Syst 2013;S6: 004.  Back to cited text no. 4
    
5.
National Cancer Registry Programme. Population based cancer registries 2004-2005. New Delhi: Indian Council of Medical Research; 2008. [www.ncrpindia.org/Reports/PBCR_Rpt_2004_05.aspx].  Back to cited text no. 5
    
6.
Fearon ER, Vogelstein B. A genetic model for colorectal tumorigenesis. Cell 1990; 61:759-67.  Back to cited text no. 6
    
7.
Ciardiello F, Tortora G. Epidermal growth factor receptor (EGFR) as a target in cancer therapy: Understanding the role of receptor expression and other molecular determinants that could influence the response to anti-EGFR drugs. Eur J Cancer 2003; 39:1348-54.  Back to cited text no. 7
    
8.
Shields JM, Pruitt K, McFall A, Shaub A, Der CJ. Understanding Ras: 'It ain't over 'til it's over'. Trends Cell Biol 2000;10:147-54.  Back to cited text no. 8
    
9.
Traxler P, Bold G, Buchdunger E, Caravatti G, Furet P, Manley P, et al. Tyrosine kinase inhibitors: From rational design to clinical trials. Med Res Rev 2001; 21:499-512.  Back to cited text no. 9
    
10.
Lièvre A, Bachet JB, Le Corre D, Boige V, Landi B, Emile JF, et al. KRAS mutation status is predictive of response to cetuximab therapy in colorectal cancer. Cancer Res 2006; 66:3992-5.  Back to cited text no. 10
    
11.
Amado RG, Wolf M, Peeters M, Van Cutsem E, Siena S, Freeman DJ, et al. Wild-type KRAS is required for panitumumab efficacy in patients with metastatic colorectal cancer. J Clin Oncol 2008; 26:1626-34.  Back to cited text no. 11
    
12.
Di Fiore F, Blanchard F, Charbonnier F, Le Pessot F, Lamy A, Galais MP, et al. Clinical relevance of KRAS mutation detection in metastatic colorectal cancer treated by Cetuximab plus chemotherapy. Br J Cancer 2007 23;96:1166-9.  Back to cited text no. 12
    
13.
Andreyev HJ, Norman AR, Cunningham D, Oates JR, Clarke PA. Kirsten ras mutations in patients with colorectal cancer: The multicenter "RASCAL" study. J Natl Cancer Inst 1998;90:675-84.  Back to cited text no. 13
    
14.
Van Cutsem E, Nowacki M, Lang I, Cascinu S, Shchepotin I, Maurel J, et al. Randomized phase III study of irinotecan and 5-FU/FA with or without cetuximab in the first-line treatment of patients with metastatic colorectal cancer (mCRC): The CRYSTAL trial. In: Program and Abstracts of the 43rd American Society of Clinical Oncology Annual Meeting; June 1-5, 2007; Chicago, IL. Abstract 4000.  Back to cited text no. 14
    
15.
Van Cutsem E, Lang I, D'haens G, Moiseyenko, Zaluski J, Folprecht G, et al. KRAS status and efficacy in the first-line treatment of patients with metastatic colorectal cancer (mCRC) treated with FOLFIRI with or without cetuximab: The CRYSTAL experience. In: Program and Abstracts of the 44rd American Society of Clinical Oncology Annual Meeting; May 30-June 3, 2008; Chicago, IL. Abstract 2.  Back to cited text no. 15
    
16.
Bokemeyer C, Bondarenko I, Hartmann JT, De Braud FG, Volovat C, Nippgen J, et al. KRAS status and efficacy of first-time treatment of patients with metastatic colorectal cancer (mCRC) with FOLFOX with or without cetuximab: The OPUS experience. In: Program and abstracts of the 44rd American Society of Clinical Oncology Annual Meeting; May 30-June 3, 2008; Chicago, IL. Abstract 4000.  Back to cited text no. 16
    
17.
Punt CJ, Tol J, Rodenburg CJ, Cats A, Creemers G, SchramaJG. et al. Randomized phase III study of capecitabine, oxaliplatin, and bevacizumab with or without cetuximab in advanced colorectal cancer (ACC), the CAIRO2 study of the Dutch Colorectal Cancer Group (DCCG). In: Program and abstracts of the 44rd American Society of Clinical Oncology Annual Meeting; May 30-June 3, 2008; Chicago, IL. Abstract LBA4011.  Back to cited text no. 17
    
18.
Hecht JR, Mitchell E, Chidiac T, Carroll Scroggin, Christopher Hagenstad, David Spigel, et al. An updated analysis of safety and efficacy of oxaliplatin (Ox)/bevacizumab (bev) +/-panitumumab (pmab) for first-line treatment (tx) of metastatic colorectal cancer (mCRC) from a randomized controlled trial (PACCE). In: Program and abstracts of the 2008 Gastrointestinal Cancers Symposium; January 25-27, 2008; Orlando, FL. Abstract 273.  Back to cited text no. 18
    
19.
Jimeno A, Messersmith WA, Hirsch FR, Franklin WA, Eckhardt SG. KRAS mutations and sensitivity to epidermal growth factor receptor inhibitors in colorectal cancer: Practical application of patient selection. J Clin Oncol 2009;27:1130-6.  Back to cited text no. 19
    
20.
Allegra CJ, Jessup JM, Somerfield MR, Hamilton SR, Hammond EH, Hayes DF, et al. American Society of Clinical Oncology provisional clinical opinion: Testing for KRAS gene mutations in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor monoclonal antibody therapy. J Clin Oncol 2009;27:2091-6.  Back to cited text no. 20
    
21.
Guidelines Established for KRAS Mutation Testing of Colorectal Carcinoma Samples: Practice Guidelines Established for KRAS Mutation Testing in Colorectal Cancers: National Comprehensive Cancer Network Guidelines on Colon and Rectal Cancers. PA, USA: NCCN; 2008.  Back to cited text no. 21
    
22.
Bos JL. Ras oncogenes in human cancer: A review. Cancer Res 1989;49:4682-9.  Back to cited text no. 22
    
23.
De Roock W, Piessevaux H, De Schutter J, Janssens M, De Hertogh G, Personeni N, Biesmans B, Van Laethem JL, Peeters M, Humblet Y, Van Cutsem E, Tejpar S. KRAS wild-type state predicts survival and is associated to early radiological response in metastatic colorectal cancer treated with cetuximab. Ann Oncol. 2008 Mar;19(3):508-15.  Back to cited text no. 23
    
24.
Kressner U, Bjørheim J, Westring S, Wahlberg SS, Påhlman L, Glimelius B, et al. Ki-ras mutations and prognosis in colorectal cancer. Eur J Cancer 1998;34:518-21.  Back to cited text no. 24
    
25.
Riely GJ, Ladanyi M. KRAS mutations: An old oncogene becomes a new predictive biomarker. J Mol Diagn 2008;10:493-5.  Back to cited text no. 25
    
26.
Breivik J, Meling GI, Spurkland A, Rognum TO, Gaudernack G. K-ras mutation in colorectal cancer: Relations to patient age, sex and tumour location. Br J Cancer 1994;69:367-71.  Back to cited text no. 26
    
27.
Shen H, Yuan Y, Hu HG, Zhong X, Ye XX, Li MD, et al. Clinical significance of K-ras and BRAF mutations in Chinese colorectal cancer patients. World J Gastroenterol 2011;17:809-16.  Back to cited text no. 27
    
28.
Sammoud S, Khiari M, Semeh A, Amine L, Ines C, Amira A, et al. Relationship between expression of ras p21 oncoprotein and mutation status of the K-ras gene in sporadic colorectal cancer patients in Tunisia. Appl Immunohistochem Mol Morphol 2012;20:146-52.  Back to cited text no. 28
    
29.
Wu CM, Tang R, Wang JY, Changchien CR, Hsieh LL. Frequency and spectrum of K-RAS codons 12 and 13 mutations in colorectal adenocarcinomas from Taiwan. Cancer Genet Cytogenet 2005;158:55-60.  Back to cited text no. 29
    
30.
Okulczyk B, Piotrowski Z, Kovalchuk O, Nikliński J, Chyczewski L. Evaluation of K-RAS gene in colorectal cancer. Folia Histochem Cytobiol 2003;41:97-100.  Back to cited text no. 30
    
31.
Breivik J, Lothe RA, Meling GI, Rognum TO, Børresen-Dale AL, Gaudernack G. Different genetic pathways to proximal and distal colorectal cancer influenced by sex-related factors. Int J Cancer 1997;74:664-9.  Back to cited text no. 31
    
32.
Phang T, Shi C, Wee A, Ngoi S, Li B, Lee H, et al. K-ras mutation in colorectal carcinomas from singapore. Int J Oncol 1995;6:191-5.  Back to cited text no. 32
    
33.
Knijn N, Mekenkamp LJ, Klomp M, Vink-Börger ME, Tol J, Teerenstra S, et al. KRAS mutation analysis: A comparison between primary tumours and matched liver metastases in 305 colorectal cancer patients. Br J Cancer 2011;104:1020-6.  Back to cited text no. 33
    
34.
Sorich MJ, Wiese MD, Rowland A, Kichenadasse G, McKinnon RA, Karapetis CS. Extended RAS mutations and anti-EGFR monoclonal antibody survival benefit in metastatic colorectal cancer: A meta-analysis of randomized, controlled trials. Ann Oncol 2015;26:13-21.  Back to cited text no. 34
    
35.
Stein A, Bokemeyer C. How to select the optimal treatment for first line metastatic colorectal cancer. World J Gastroenterol 2014;20:899-907.  Back to cited text no. 35
    
36.
Slattery ML, Curtin K, Anderson K, Ma KN, Edwards S, Leppert M, et al. Associations between dietary intake and Ki-ras mutations in colon tumors: A population-based study. Cancer Res 2000;60:6935-41.  Back to cited text no. 36
    
37.
DxS/THERASCREEN® Package Insert. UK: DsX, Manchester; 2009. https://www.qiagen.com/resources/download.aspx?id=0457593b  Back to cited text no. 37
    
38.
(A) Ries L AG, Melbert D, Krapcho M, et al. SEER cancer statistics review, 1975–2005. Bethesda, MD: 2008. (B) Jemal A, Clegg LX, Ward E, Ries LA, Wu X, Jamison PM, Wingo PA, Howe HL, Anderson RN, Edwards BK. Annual report to the nation on the status of cancer, 1975-2001, with a special feature regarding survival. Cancer. 2004 1;101 (1):3-27. (C) http://seer.cancer.gov/statfacts/html/colorect.html.  Back to cited text no. 38
    
39.
Angulo B, García-García E, Martínez R, Suárez-Gauthier A, Conde E, Hidalgo M, et al. A commercial real-time PCR kit provides greater sensitivity than direct sequencing to detect KRAS mutations: A morphology-based approach in colorectal carcinoma. J Mol Diagn 2010;12:292-9.  Back to cited text no. 39
    
40.
Whitehall V, Tran K, Umapathy A, Grieu F, Hewitt C, Evans TJ, et al. A multicenter blinded study to evaluate KRAS mutation testing methodologies in the clinical setting. J Mol Diagn 2009;11:543-52.  Back to cited text no. 40
    
41.
Sahoo R, Harini VV, Babu VC, Patil Okaly GV, Rao S, Nargund A, et al. Screening for EGFR mutations in lung cancer, a report from India. Lung Cancer 2011; 73:316-9.  Back to cited text no. 41
    
42.
Al-Allawi NA, Ismaeel AT, Ahmed NY, Merza NS. The frequency and spectrum of K-ras mutations among Iraqi patients with sporadic colorectal carcinoma. Indian J Cancer 2012; 49:163-8.  Back to cited text no. 42
[PUBMED]  Medknow Journal  
43.
Samowitz WS, Curtin K, Schaffer D, Robertson M, Leppert M, Slattery ML. Relationship of Ki-ras mutations in colon cancers to tumor location, stage, and survival: A population-based study. Cancer Epidemiol Biomarkers Prev 2000; 9:1193-7.  Back to cited text no. 43
    
44.
Elnatan J, Goh HS, Smith DR. C-KI-RAS activation and the biological behaviour of proximal and distal colonic adenocarcinomas. Eur J Cancer 1996; 32A: 491-7.  Back to cited text no. 44
    
45.
Einspahr JG, Martinez ME, Jiang R, Hsu CH, Rashid A, Bhattacharrya AK, et al. Associations of Ki-ras proto-oncogene mutation and p53 gene overexpression in sporadic colorectal adenomas with demographic and clinicopathologic characteristics. Cancer Epidemiol Biomarkers Prev 2006;15:1443-50.  Back to cited text no. 45
    
46.
Baskin Y, Dagdeviren YK, Calibasi G, Canda AE, Sarioglu S, Ellidokuz H, Oztop I. KRAS mutation profile differences between rectosigmoid localized adenocarcinomas and colon adenocarcinomas. J Gastrointest Oncol. 2014 Aug;5(4):265-9  Back to cited text no. 46
    
47.
Lee KN, Lee OY. Intestinal microbiota in pathophysiology and management of irritable bowel syndrome. World J Gastroenterol 2014; 20:8886-97.  Back to cited text no. 47
    
48.
Faulkner NE, Da Silva MM, Heim RA, Horten BC, Rohlfs EM, Rosenblum LS, et al. KRAS Mutation Analyses of >16,500 Colorectal Carcinomas. Presented at: ASCO–NCI–EORTC Annual Meeting: Molecular Markers in Cancer. Brussels, Belgium, 18-20 October, 2010.  Back to cited text no. 48
    
49.
Parkin DM, Whelan SL, Ferlay L, Young RJ. Cancer Incidence in Five Continents (IARC Sci. Publ. No. 143) Series. Vol. 143. Lyon: International Agency for Research on Cancer; 1997. p. 566-7.  Back to cited text no. 49
    
50.
Scott RJ, Fox SB, Desai J, Grieu F, Amanuel B, Garrett K, et al. KRAS mutation testing of metastatic colorectal cancer in Australia: Where are we at? Asia Pac J Clin Oncol 2014; 10:261-5.  Back to cited text no. 50
    
51.
Nakanishi R, Harada J, Tuul M, Zhao Y, Ando K, Saeki H, et al. Prognostic relevance of KRAS and BRAF mutations in Japanese patients with colorectal cancer. Int J Clin Oncol 2013; 18:1042-8.  Back to cited text no. 51
    
52.
Blons H, Emile JF, Le Malicot K, Julié C, Zaanan A, Tabernero J, et al. Prognostic value of KRAS mutations in stage III colon cancer: Post hoc analysis of the PETACC8 phase III trial dataset. Ann Oncol 2014; 25:2378-85.  Back to cited text no. 52
    
53.
Phipps AI, Buchanan DD, Makar KW, Win AK, Baron JA, Lindor NM, et al. KRAS-mutation status in relation to colorectal cancer survival: The joint impact of correlated tumour markers. Br J Cancer 2013; 108:1757-64.  Back to cited text no. 53
    
54.
Díaz-Rubio E, Gómez-España A, Massutí B, Sastre J, Reboredo M, Manzano JL, et al. Role of Kras status in patients with metastatic colorectal cancer receiving first-line chemotherapy plus bevacizumab: A TTD group cooperative study. PLoS One 2012; 7:e47345.  Back to cited text no. 54
    
55.
Brink M, de Goeij AF, Weijenberg MP, Roemen GM, Lentjes MH, Pachen MM, et al. K-ras oncogene mutations in sporadic colorectal cancer in The Netherlands Cohort Study. Carcinogenesis 2003; 24:703-10.  Back to cited text no. 55
    
56.
Zhu XL, Cai X, Zhang L, Yang F, Sheng WQ, Lu YM, et al. KRAS and BRAF gene mutations in correlation with clinicopathologic features of colorectal carcinoma in Chinese. Zhonghua Bing Li Xue Za Zhi 2012; 41:584-9.  Back to cited text no. 56
    
57.
Bisht S, Ahmad F, Sawaimoon S, Bhatia S, Das BR. Molecular spectrum of KRAS, BRAF, and PIK3CA gene mutation: Determination of frequency, distribution pattern in Indian colorectal carcinoma. Med Oncol 2014;31:124.  Back to cited text no. 57
    
58.
Sameer AS, Chowdhri NA, Abdullah S, Shah ZA, Siddiqi MA. Mutation pattern of K-ras gene in colorectal cancer patients of Kashmir: A report. Indian J Cancer 2009; 46:219-25.  Back to cited text no. 58
[PUBMED]  Medknow Journal  
59.
Sinha R, Hussain S, Mehrotra R, Kumar RS, Kumar K, Pande P, et al. Kras gene mutation and RASSF1A, FHIT and MGMT gene promoter hypermethylation: Indicators of tumor staging and metastasis in adenocarcinomatous sporadic colorectal cancer in Indian population. PLoS One 2013; 8:e60142.  Back to cited text no. 59
    



 
 
    Tables

  [Table 2], [Table 2], [Table 3], [Table 4], [Table 5]



 

Top
Print this article  Email this article
 

    

  Site Map | What's new | Copyright and Disclaimer
  Online since 1st April '07
  © 2007 - Indian Journal of Cancer | Published by Wolters Kluwer - Medknow