title: Molecular markers and pathway analysis of colorectal carcinoma in the Middle East.
abstract: BACKGROUND
  Colorectal cancer (CRC) is one of the most common cancers in the world. A newly proposed integrated pathway comprising traditional, alternate, and serrated pathways by genetic and epigenetic factors was defined recently and hypothesized to play a role in the pathogenesis of CRC; however, to the authors' knowledge, there is a paucity of information regarding these proposed molecular pathways in different ethnic groups.
  
  
  METHODS
  Molecular characterization of 770 CRC specimens was performed for microsatellite instability, BRAF, and KRAS by polymerase chain reaction and 500 cases for CpG island methylator phenotype (CIMP) high phenotype by MethyLight technology. Tumors were assigned to different molecular pathways and examined for clinicopathological correlation and survival analysis.
  
  
  RESULTS
  The traditional pathway constituted 33.4% of CRC cases, the alternate pathway comprised 11.6%, and the serrated molecular pathway accounted for only 0.8% of Middle Eastern CRC cases. Approximately 54.2% of CRC cases did not qualify to fit into any pathway and thus were designated as an unassigned group. Molecular pathways were found to be significantly associated with tumor site and grade. A subset of cases with an uncategorized pathway demonstrated a significant survival difference (P = .0079).
  
  
  CONCLUSIONS
  The serrated pathway was found to account for a very low percentage of the CRC patient cohort in the current study. The unassigned group accounted for the majority of Middle Eastern CRC cases, and therefore methods of CRC pathway analysis might not be applicable to this ethnic group. The current study demonstrates the need to unravel the molecular genetic basis of this disease to further subcategorize these CRC cases. It also identifies a need for further studies on different populations for a better understanding of their exact role and incidence.
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Shaham
authors.initials: S
authors.lastname: Beg
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Abdul K
authors.initials: AK
authors.lastname: Siraj
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Sarita
authors.initials: S
authors.lastname: Prabhakaran
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Rong
authors.initials: R
authors.lastname: Bu
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Maha
authors.initials: M
authors.lastname: Al-Rasheed
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Mehar
authors.initials: M
authors.lastname: Sultana
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Zeeshan
authors.initials: Z
authors.lastname: Qadri
authors.affiliation: Department of Surgery, Security Forces Hospital, Riyadh, Saudi Arabia.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al-Assiri
authors.affiliation: Department of Surgery, Security Forces Hospital, Riyadh, Saudi Arabia.
authors.forename: Rami
authors.initials: R
authors.lastname: Sairafi
authors.affiliation: Department of Pathology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Fouad
authors.initials: F
authors.lastname: Al-Dayel
authors.affiliation: Colorectal Unit, Department of Surgery, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Nasser
authors.initials: N
authors.lastname: Al-Sanea
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Shahab
authors.initials: S
authors.lastname: Uddin
authors.affiliation: Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.|Department of Pathology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Khawla S
authors.initials: KS
authors.lastname: Al-Kuraya
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000208:ethnology* / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D008877:Middle East / Q000453:epidemiology; D009154:Mutation / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D012189:Retrospective Studies; D015398:Signal Transduction / Q000235:genetics*; D018631:ras Proteins / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: Middle East; alternate pathway; colorectal cancer; molecular pathways; serrated pathway; traditional pathway