Edorium Journal of

Tumor Biology

 
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Original Article
 
Molecular analysis and clinicopathologic features of advanced colorectal cancer in Algerian patients
Kenza Boudida-Berkane1, Hind Benchaa2, Sonia Ait younes3, Hayet Ait Kaci4, Mohammed Oukkal5, Hacene Mahfouf6, Kamel Bouzid7
1University Sciences &Technology, Algiers, Algeria. Researcher in Molecular oncology laboratory Medical Oncology Department Pierre & Marie, Center Algiers, Algeria.
2University Algiers1 Medical Oncology Department Pierre & Marie Curie Center, Algiers, Algeria.
3University Algiers1, Anatomo pathology Department, Mustapha Hospital Algiers, Algeria.
4University Algiers1, Anatomo pathology Department Pierre & Marie Center, Algiers, Algeria.
5University Algiers1, Medical Oncology Department Pierre & Marie Curie Center, Algiers Algeria.
6University Algiers1, Medical Oncology Department, Rouiba Hospital, Algiers, Algeria.
7University Algiers1, Head of the Medical Oncology Department & Director of Molecular oncology laboratory, Medical Oncology Department Pierre & Marie Curie Center, Algiers, Algeria.

Article ID: 100004T09KB2016
doi:10.5348/T09-2016-4-OA-1

Address correspondence to:
Kenza Boudida-Berkane
University Sciences &Technology, Algiers
Algeria

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Boudida-Berkane K, Benchaa H, Younes SA, Kaci HA, Oukkal M, Mahfouf H, Bouzid K. Molecular analysis and clinicopathologic features of advanced colorectal cancer in Algerian patients. Edorium J Tumor Bio 2016;3:1–8.


Abstract
Aims: This retrospective study aims to analyze tumors hot spot mutations frequency in KRAS, BRAF and microsatellite instability (MSI) status of tumors in Algerian patients with advanced colorectal cancer (CRC) which can predict prognosis and contribute to decisions on treatment strategies.
Methods: KRAS exon 2, BRAF exon 15 were analyzed by direct sequencing of amplified PCR products in 102 tumors patients with advanced CRC cancer. The MSI was determined using a panel of five mononucleotide markers (BAT25, BAT26, NR21, NR22 and NR24).
Results: BRAF and KRAS mutations were detected in 4.9% and 31.3% of the tumors patients respectively. Activating mutations in codon 12 and 13 in KRAS was located in the right colon 40.6% versus 25% in the left colon. (62.5%) with KRAS mutations are well or moderately differentiated. The aminoacid changes are more frequently observed in codon 12 (29/32) than in codon 13 (3/32) and G12D (43.8%) is the most frequent mutation. BRAF v600E mutation is observed in proximal colon in 3 of 5 tumors (60%) in patients with older age > 50 years. (53.1%).BRAF wild type tumors (79%) were associated with MSI-H.
Conclusion: The results of KRAS and BRAF mutation analysis could be used in the selection of Algerian patients with CRC for anti epidermal growth factor receptor (anti-EGFR) therapy and MSI-H status associated with BRAF wild type (Wt) may be suggesting the possible presence of Hereditary non polyposis colorectal cancer (HNPCC) syndrome.

Keywords: Algeria, BRAF and KRAS mutations, Microsatellite instability (MSI), Colorectal cancer (CRC), Non polyposis colorectal cancer


Introduction

Colorectal cancer (CRC) is a heterogeneous disease and the third most common cancer in the western countries [1]. Its incidence rate is lower in North Africa [2] but has significantly increased these last two decades. In Algeria, CRC is the second most common cancer after lung cancer in men and breast cancer in women [3]. More than half of the patients were staged III and IV at the diagnosis and are younger than the patients in the western countries [4]. The possible causes of this include genetic, environmental and lifestyle factors [5]. Diet, obesity and comorbidities such as diabetes increase the risk of developing a cancer. Several factors such as socioeconomic status, screening, diagnosis and differences in treatment can explain the different health outcomes among patients [6]. Despite progress in recent years in the treatment of CRC with the use of the anti- EGFR and anti-vascular epidermal growth factor (anti-VEGF) agents which have significantly improved the survival of CRC patients [7], mortality remains high in Algeria. Molecular biomarkers that are clinically used have become important and may provide treatment with anti-EGFR agents [8]. It has been reported that patients with mutated RAS, do not benefit from anti-EGFR therapy [9] [10] . The aim of the current study was to detect some molecular alterations MSI, BRAF, KRAS which proved to be significant prognosis and /or predictive markers in the daily clinical practice and which may help define a better management of the Algerian patients with CRC. The development of platforms for detection of molecular alterations including BRAF and RAS hot spot mutations in tumors will facilitate the prescription of target therapies in Algeria.


Patients And Methods

Clinical data was collected from 102 Algerian patients with advanced CRC histopathologically proven and who were being treated at the medical oncology department in Pierre and Mary Curie Center, a specialized University hospital in Algiers, Algeria, between 2006–2009 and after radical surgical resection. All participants signed an informed consent and the study was approved by the ethical committee of our institution. Clinicopathological information including age at diagnosis, sex, tumor location, stage, pathological tumor staging system (p TNM/UICC), were available for all patients.

TISSUE SELECTION
Primary tumors paraffin included were cut in 4 µm sections and stained with Hematoxylin and Eosin (H&E) for histopathological examination. Formalin fixed and paraffin embedded (FFPE) tumor sections were reviewed by pathologist to confirm diagnosis and define tumor areas containing 50 to 70% tumor cellularity and areas of adjacent normal tissue (25 to 30%) which were immersed in xylene and ethanol. When necessary, the proportion of tumoral cells was maximed by macrodissection.

DNA ISOLATION
Genomic DNA was extracted using the Qiamp miniKit Qiagen following the manufacturer's recommendations (Qiagen courtaboeuf, France) and quantified by spectrophotometry with nanodrop (Thermo Fisher scientific).

MOLECULAR ANALYSIS

Microsatellite instability (MSI) status
Microsatellite markers (Bat25, Bat 26, NR 21, NR 22 and NR24) a pentaplex of mononucleotide repeat were used to evaluate MSI status by polymerase chain reaction (PCR). Instability at only one of the five markers tested was labeled Microsatellite Low (MSL). Instability for two for more was MSI-High (MSI-H) and no instability at any of the five markers tested was labeled Micro-satellite Stable (MSS). In this study MSI-L and MSS are combined into one group which is non MSI-H.

KRAS and BRAF status: Genomic DNA was analyzed by direct sequencing of amplified PCR products. (Applied Biosystem).

STATISTICAL ANALYSIS
Different variables were compared using chi-square test and Fisher student test. P-value < 0.05 was considered statistically significant.


Results

In this study, we analyzed 102 advanced CRC tumors from Algerian patients. Clinicopathological features are summarized in (Table 1). The gender distribution was 58 males (56.8%) and 44 females (43.2%) (p = 830) with 48 patients (47.1%) < 50 years and 54 > 50 years (52.9%) (p = 0.830) range (18–83 years). Tumors location was distributed to the proximal (28.4%), distal (36.3%) and rectum (35.3%) (p = 0.130). Histological analysis demonstrated 41 (40.2%) well differentiated 39 (38.2%) moderately differentiated and 22 (21.6%) poorly differentiated adenocarcinomas (p = 0.130). Of the 102 tumors analyzed, KRAS mutations in exon 2 codons 12–13 were detected in 32/102 (31. 4%). The most prevalent mutation observed in codon 12 was G12D (43.8%), G12A (25%), followed by G12V (9.3%), G12C and G12S (6.3%) respectively and in codon 13 we found G13D (9.3%) (Table 2). Analysis of KRAS mutations showed 40.6%, in the proximal colon, 25% in the distal colon and 34.4% in the rectum. Correlation of KRAS mutations with gender showed that KRAS mutations were more frequently observed in women (62.5%) than in men (37.5%), and no significant difference was found in other variables. MSI and BRAF status were determined of all colorectal tumors cases and MSI-High (MSI-H) was detected in 19 of 102 (18.6%) tumors patients analyzed. 17 of 19 (89.5%) tumors showed instability in all 5 markers used in this study. BRAF mutation was observed in 5 cases (4.9%) analyzed with a wild type (Wt) profile in KRAS. The majority of tumors MSI-H, 15/19 (79%) were BRAF Wild Type (Wt). Molecular markers included MSI status, KRAS and BRAF mutations in 102 tumors of Algerian patients analyzed are regrouped in (Table 3). As shown in (Table 4) correlation of tumor location and molecular markers shown KRAS mutation at the right colon 40.6% (13/32) versuss 25% (8/32) in the left colon and 34.4% (11/32) in the rectum. 3 of 5 tumors (60%) with v600E BRAF mutation were located significantly in proximal colon and found in patients older of 50 years.

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Table 1: Correlation of KRAS, BRAF mutations with clinicopathological parameters in advanced and metastatic colorectal cancer of primary tumor


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Table 2: Number and type of mutations in exon 2 codons 12, 13 and corresponding aminoacids of the KRAS gene. In advanced CRC of primary tumors.


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Table 3: MSI status, mutations in exon 2, codons 12, 13 of the KRAS gene and exon 15 v600E BRAF gene in advanced CRC of primary tumors.



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Table 4: Correlation of tumor location and molecular markers in advanced and metastatic CRC of primary tumors.



Discussion

The results of this preliminary study show that 70/102 (68.6%) Algerian patients with CRC could benefit from anti-EGFR therapy. EGFR has become an important target for treatment decisions making of CRC. So it has become important to multiply the platforms for determination of molecular alterations in tumors in Algeria, which would facilitate the prescription of target therapy in the country. Activating KRAS mutations in codons 12 and 13 have a clinical impact on patients with CRC [11] and predict resistance to anti-EGFR antibodies, cetuximab a human-mouse chimeric IgG1 and panitumumab a human IgG2 monoclonal antibodies which have been entered in the personalized treatment in patients with CRC [12]. KRAS is part of the EGFR signaling pathway downstream to EGFR. Activation of the pathway leads to the modulation of angiogenesis, cell migration, proliferation and metastasis formation. In this study, we identified 31.4% of tumors with KRAS codons 12, 13 mutations and a higher frequency in women, 20/32, (62.5%) versus 12/32 (37.5%) in males. The most prevalent mutations were observed in codon 12 with (90.7 %) than in codon 13 (9.3%). We found that the most frequent location was in the proximal colon with 40.6% versus 25% in the distal colon. No significant age difference was found in our study between patients with KRAS mutated tumors and Wt KRAS tumors and no association has been found between KRAS mutations and MSI phenotype, this is in accordance with results of other research studies [13][14]. Recently, prospective and retrospective analyses demonstrated that patients with tumors KRAS and NRAS Wt in exons 2, 3 and 4 predict benefit from anti-EGFR therapy associated with chemotherapy [15] [16]. The KRAS mutations are also detected in lung [17], pancreatic and cervical cancers and the anti-EGFR therapies have shown to be effective in patients with CRC. The prognostic role of KRAS mutations is more debated, and has been associated with a worse prognosis in some studies [14]. The BRAF Wt is also required for response to cetuximab or panitumumab [18] suggesting that BRAF analysis should be used with KRAS for the selection of the patients [19]. We observed that activating mutation of BRAF was (5%) in this study whereas it is about 10–20% in the majority of studies performed on sporadic CRC in western countries [20]. This mutation was found to be more frequent in the right colon and old age at presentation 3/5 (60%). However, no activating mutation has been observed at codon 600 of BRAF in 88 cases analyzed in western Africa (Ghana) with a high frequency of MSI-H [21] and the highest frequency is reported in the United States (21%). A low incidence was observed in Taiwan 1% [22], in Morocco 1.6% [23] and 5.4% [24], in Tunisia 2% [25], in Saudi Arabia 2.5% [26], in China, 3.8% [27], Japan, 6.5% [28], Korea and 9.6% [29]. These variations could be attributed to ethnic differences and the effect of other environmental and genetic factors. The implication of genetic factors in a population where the overall incidence of CRC is low, would suggest a greater proportion of familial versus sporadic cases. More studies are needed to confirm these differences. The BRAF mutation detection could have been also influenced by the mutation analysis methodology. Variety of methods including Sanger sequencing, pyrosequencing, high resolution melting, allele -specific PCR and new generation sequencing have been used and may have contributed to the wide variations in the prevalence of those mutations. The BRAF mutation was proposed as a marker to discriminate between sporadic cancer and HNPCC labeled also Lynch syndrome [30]. Its incidence which is 3–5% of CRC cases in western countries is higher in Algeria (7–10%) [4]. BRAF mutation is associated with MSI-H through its relationship to high-level CpG island methylator phénotype (CIMP) and with worse prognosis [31][32]. The prognostic value of MSI is influenced by the BRAF status which is a genetic consequence of a MisMatch Repair genes (MMR) defect [33]. Other studies suggested that the prognostic effects of BRAF mutations depended on the MSI status [34][35]. A negative prognostic effect of BRAF mutations was reported only for MSS patients but not for patients with MSI [36] and a predictive effect of BRAF for response to anti-EGFR therapy in metastatic colorectal cancer is not required for treatment decision but it may be useful as a prognostic factor and could be used for better management of patients with CRC because of its implication on microsatellite instability [14]. Our results showed approximately 80% tumors MSI-H / BRAF Wt and suggest the possible presence of HNPCC syndrome. MSI-H tumors in CRCs may be sporadic or associated with Lynch syndrome and germline mutation analysis is required for tumors MSI-H that are BRAF wild type because mutations in the BRAF gene was found in sporadic MSI-H tumors but not in HNPCC syndrome [37][38].


Conclusion

In conclusion, we have found that the clinicopathologic characteristics in Algerian patients with CRC are similar to those reported in other studies. As a result, a total of 70% Algerian patients could benefit from anti-EGFR therapy. RAS testing had an impact on therapeutic strategy and must be realized in all oncology departments in Algeria. In order to reduce the time of the process and to prescribe targeted therapy for the patients with CRC in the daily clinical practice. A limitation of this study is the absence of data of KRAS exons 3–4 and NRAS exons 2-3-4 which have been established as predictive markers of the response to EGFR-targeted therapy. Our study suggests also the possibility of the presence of the HNPCC syndrome and use of BRAF molecular analysis is only a step before germline genetic testing. Screening program should be set up to determine the real incidence rate of the HNPCC which tends to be more frequent in Algeria than in western countries. Further studies including a large number of patients are needed to confirm our results.


Acknowledgements

This work was supported by the Direction Générale de la Recherche Scientifique et du Développement Technologique in Algeria, (DGRSDT), Ministére de l'Enseignement Supérieur et de la Recherche Scientifique (MESRS) and Agence Thématique de la Recherche Scientifique Algéria (ATRS).

We thank, Helene Blons , Pierre Laurent Puig: European Hospital Georges Pompidou (HEGP), Paris, France and Jaqueline Lehmann, Hughes De Thé: Saint Louis Hospital, Paris, France for initiation of analysis molecular biology tests.


References
  1. Center MM, Jemal A, Smith RA, Ward E. Worldwide variations in colorectal cancer. CA Cancer J Clin 2009 Nov-Dec;59(6):366–78.   [CrossRef]   [Pubmed]    Back to citation no. 1
  2. Center MM, Jemal A, Ward E. International trends in colorectal cancer incidence rates. Cancer Epidemiol Biomarkers Prev 2009 Jun;18(6):1688–94.   [CrossRef]   [Pubmed]    Back to citation no. 2
  3. Hamdi-Cherif M, Bidoli E, Birri S, et al. Cancer estimation of incidence and survival in Algeria 2014. J Cancer Res Ther 2015;3(9):100–104.   [CrossRef]    Back to citation no. 3
  4. Registre du cancer Alger, Institut National Santé Publique INSP, Ministère de la Santé et des populations, Alger, Algeria. 2009.    Back to citation no. 4
  5. Siegel R, Ward E, Brawley O, Jemal A. Cancer statistics, 2011: the impact of eliminating socioeconomic and racial disparities on premature cancer deaths. CA Cancer J Clin 2011 Jul-Aug;61(4):212–36.   [CrossRef]   [Pubmed]    Back to citation no. 5
  6. Doubeni CA, Laiyemo AO, Major JM, et al. Socioeconomic status and the risk of colorectal cancer: an analysis of more than a half million adults in the National Institutes of Health-AARP Diet and Health Study. Cancer 2012 Jul 15;118(14):3636–44.   [CrossRef]   [Pubmed]    Back to citation no. 6
  7. Schwartzberg LS, Rivera F, Karthaus M, et al. PEAK: a randomized, multicenter phase II study of panitumumab plus modified fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) or bevacizumab plus mFOLFOX6 in patients with previously untreated, unresectable, wild-type KRAS exon 2 metastatic colorectal cancer. J Clin Oncol 2014 Jul 20;32(21):2240–7.   [CrossRef]   [Pubmed]    Back to citation no. 7
  8. Sideris M, Papagrigoriadis S. Molecular biomarkers and classification models in the evaluation of the prognosis of colorectal cancer. Anticancer Res 2014 May;34(5):2061–8.   [Pubmed]    Back to citation no. 8
  9. Di Fiore F, Blanchard F, Charbonnier F, et al. Clinical relevance of KRAS mutation detection in metastatic colorectal cancer treated by Cetuximab plus chemotherapy. Br J Cancer 2007 Apr 23;96(8):1166–9.   [CrossRef]   [Pubmed]    Back to citation no. 9
  10. Lièvre A, Bachet JB, Le Corre D, et al. KRAS mutation status is predictive of response to cetuximab therapy in colorectal cancer. Cancer Res 2006 Apr 15;66(8):3992–5.   [Pubmed]    Back to citation no. 10
  11. Febbo PG, Ladanyi M, Aldape KD, et al. NCCN Task Force report: Evaluating the clinical utility of tumor markers in oncology. J Natl Compr Canc Netw 2011 Nov;9 Suppl 5:S1–32.   [Pubmed]    Back to citation no. 11
  12. Amado RG, Wolf M, Peeters M, et al. Wild-type KRAS is required for panitumumab efficacy in patients with metastatic colorectal cancer. J Clin Oncol 2008 Apr 1;26(10):1626–34.   [CrossRef]   [Pubmed]    Back to citation no. 12
  13. 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 Nov;9(11):1193–7.   [Pubmed]    Back to citation no. 13
  14. Cushman-Vokoun AM, Stover DG, Zhao Z, Koehler EA, Berlin JD, Vnencak-Jones CL. Clinical utility of KRAS and BRAF mutations in a cohort of patients with colorectal neoplasms submitted for microsatellite instability testing. Clin Colorectal Cancer 2013 Sep;12(3):168–78.   [CrossRef]   [Pubmed]    Back to citation no. 14
  15. Bokemeyer C, Köhne CH, Ciardiello F, et al. FOLFOX4 plus cetuximab treatment and RAS mutations in colorectal cancer. Eur J Cancer 2015 Jul;51(10):1243–52.   [CrossRef]   [Pubmed]    Back to citation no. 15
  16. Douillard JY, Siena S, Cassidy J, et al. Final results from PRIME: randomized phase III study of panitumumab with FOLFOX4 for first-line treatment of metastatic colorectal cancer. Ann Oncol 2014 Jul;25(7):1346–55.   [CrossRef]   [Pubmed]    Back to citation no. 16
  17. Riely GJ, Marks J, Pao W. KRAS mutations in non-small cell lung cancer. Proc Am Thorac Soc 2009 Apr 15;6(2):201–5.   [CrossRef]   [Pubmed]    Back to citation no. 17
  18. Imamura Y, Morikawa T, Liao X, et al. Specific mutations in KRAS codons 12 and 13, and patient prognosis in 1075 BRAF wild-type colorectal cancers. Clin Cancer Res 2012 Sep 1;18(17):4753–63.   [CrossRef]   [Pubmed]    Back to citation no. 18
  19. Reimers MS, Zeestraten EC, Kuppen PJ, Liefers GJ, van de Velde CJ. Biomarkers in precision therapy in colorectal cancer. Gastroenterol Rep (Oxf) 2013 Nov;1(3):166–83.   [CrossRef]   [Pubmed]    Back to citation no. 19
  20. Di Nicolantonio F, Martini M, Molinari F, et al. Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer. J Clin Oncol 2008 Dec 10;26(35):5705–12.   [CrossRef]   [Pubmed]    Back to citation no. 20
  21. Raskin L, Dakubo JC, Palaski N, Greenson JK, Gruber SB. Distinct molecular features of colorectal cancer in Ghana. Cancer Epidemiol 2013 Oct;37(5):556–61.   [CrossRef]   [Pubmed]    Back to citation no. 21
  22. Tsai JH, Liau JY, Lin YL, et al. Frequent BRAF mutation in early-onset colorectal cancer in Taiwan: association with distinct clinicopathological and molecular features and poor clinical outcome. J Clin Pathol 2015 Oct 23. pii: jclinpath-2015–203335.   [CrossRef]   [Pubmed]    Back to citation no. 22
  23. Bennani B, Gilles S, Fina F, Mutation analysis of BRAF exon 15 and KRAS codons 12 and 13 in Moroccan patients with colorectal cancer. Int J Biol Markers 2010 Oct-Dec;25(4):179–84.   [CrossRef]   [Pubmed]    Back to citation no. 23
  24. Marchoudi N, Amrani Hassani Joutei H, Jouali F, Fekkak J, Rhaissi H. Distribution of KRAS and BRAF mutations in Moroccan patients with advanced colorectal cancer. Pathol Biol (Paris) 2013 Dec;61(6):273–6.   [CrossRef]   [Pubmed]    Back to citation no. 24
  25. Aissi S, Buisine MP, Zerimech F, et al. Somatic molecular changes and histo-pathological features of colorectal cancer in Tunisia. World J Gastroenterol 2013 Aug 28;19(32):5286–94.   [CrossRef]   [Pubmed]    Back to citation no. 25
  26. Siraj AK, Bu R, Prabhakaran S, et al. A very low incidence of BRAF mutations in Middle Eastern colorectal carcinoma. Mol Cancer 2014 Jul 8;13:168.   [CrossRef]   [Pubmed]    Back to citation no. 26
  27. Liou JM, Wu MS, Shun CT, et al. Mutations in BRAF correlate with poor survival of colorectal cancers in Chinese population. Int J Colorectal Dis 2011 Nov;26(11):1387–95.   [CrossRef]   [Pubmed]    Back to citation no. 27
  28. Yokota T, Ura T, Shibata N, et al. BRAF mutation is a powerful prognostic factor in advanced and recurrent colorectal cancer. Br J Cancer 2011 Mar 1;104(5):856–62.   [CrossRef]   [Pubmed]    Back to citation no. 28
  29. Kim B, Park SJ, Cheon JH, Kim TI, Kim WH, Hong SP. Clinical meaning of BRAF mutation in Korean patients with advanced colorectal cancer. World J Gastroenterol 2014 Apr 21;20(15):4370–6.   [CrossRef]   [Pubmed]    Back to citation no. 29
  30. Loughrey MB, Waring PM, Tan A, et al. Incorporation of somatic BRAF mutation testing into an algorithm for the investigation of hereditary non-polyposis colorectal cancer. Fam Cancer 2007;6(3):301–10.   [CrossRef]   [Pubmed]    Back to citation no. 30
  31. Lochhead P, Kuchiba A, Imamura Y, et al. Microsatellite instability and BRAF mutation testing in colorectal cancer prognostication. J Natl Cancer Inst 2013 Aug 7;105(15):1151–6.   [CrossRef]   [Pubmed]    Back to citation no. 31
  32. Birgisson H, Edlund K, Wallin U, et al. Microsatellite instability and mutations in BRAF and KRAS are significant predictors of disseminated disease in colon cancer. BMC Cancer 2015 Mar 14;15:125.   [CrossRef]   [Pubmed]    Back to citation no. 32
  33. Deng G, Bell I, Crawley S, et al. BRAF mutation is frequently present in sporadic colorectal cancer with methylated hMLH1, but not in hereditary nonpolyposis colorectal cancer. Clin Cancer Res 2004 Jan 1;10(1 Pt 1):191–5.   [CrossRef]   [Pubmed]    Back to citation no. 33
  34. Zlobec I, Kovac M, Erzberger P, et al. Combined analysis of specific KRAS mutation, BRAF and microsatellite instability identifies prognostic subgroups of sporadic and hereditary colorectal cancer. Int J Cancer 2010 Dec 1;127(11):2569–75.   [CrossRef]   [Pubmed]    Back to citation no. 34
  35. Cushman-Vokoun AM, Stover DG, Zhao Z, Koehler EA, Berlin JD, Vnencak-Jones CL. Clinical utility of KRAS and BRAF mutations in a cohort of patients with colorectal neoplasms submitted for microsatellite instability testing. Clin Colorectal Cancer 2013 Sep;12(3):168–78.   [CrossRef]   [Pubmed]    Back to citation no. 35
  36. Samowitz WS, Sweeney C, Herrick J, et al. Poor survival associated with the BRAF V600E mutation in microsatellite-stable colon cancers. Cancer Res 2005 Jul 15;65(14):6063–9.   [CrossRef]   [Pubmed]    Back to citation no. 36
  37. Domingo E, Niessen RC, Oliveira C, et al. BRAF-V600E is not involved in the colorectal tumorigenesis of HNPCC in patients with functional MLH1 and MSH2 genes. Oncogene 2005 Jun 2;24(24):3995–8.   [CrossRef]   [Pubmed]    Back to citation no. 37
  38. Bessa X, Ballesté B, Andreu M, et al. A prospective, multicenter, population-based study of BRAF mutational analysis for Lynch syndrome screening. Clin Gastroenterol Hepatol 2008 Feb;6(2):206–14.   [CrossRef]   [Pubmed]    Back to citation no. 38
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Author Contributions:
Kenza Boudida-Berkane – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Hind Benchaa – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Sonia Ait Younes – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Hayet Ait Kaci – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Mohammed Oukkal – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Hacene Mahfouf – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Kamel Bouzid – Analysis and interpretation of data, Revising it critically for important intellectual content, Final approval of the version to be published
Guarantor of submission
The corresponding author is the guarantor of submission.
Source of support
None
Conflict of interest
Authors declare no conflict of interest.
Copyright
© 2016 Kenza Boudida-Berkane et al. This article is distributed under the terms of Creative Commons Attribution License which permits unrestricted use, distribution and reproduction in any medium provided the original author(s) and original publisher are properly credited. Please see the copyright policy on the journal website for more information.



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