title: Clinicopathological Associations of K-RAS and N-RAS Mutations in Indonesian Colorectal Cancer Cohort.
abstract: BACKGROUND
  K-RAS and recently N-RAS gene mutation testing are mandatory requirements prior to anti-epidermal growth factor receptor (EGFR) monoclonal antibody treatment of metastatic CRC. Mutation prevalence and distribution in Indonesian colorectal cancer (CRC) are not known.
  
  
  METHODS
  Combined methods of PCR high-resolution melt (HRM), restriction fragment length polymorphism (RFLP), and direct DNA sequencing were used to genotype exons 2, 3, and 4 of both K-RAS and N-RAS genes for routine clinical testing of CRC patients. Descriptive analytical review of 595 consecutive CRC patients (years 2013 to 2016) was performed to find associations between gene mutations and clinicopathologic features.
  
  
  RESULTS
  This retrospective study revealed overall K-RAS gene mutation in exon 2 (codon 12 and 13) rates being 34.9%. Women (42.5%), stages I and II (43.4%), and well and moderate differentiations (37.7%) had higher frequency of K-RAS exon 2 mutations than men (29%, p = 0.006), stages (III and IV 31.9%, p = 0.05), and poor differentiation (11.8%, p = 0.002), respectively. At later period (2015-2016), 121 of 595 patients were genotyped for the remaining exons 3 and 4 of K-RAS as well as exons 2, 3, and 4 of N-RAS mutations resulting in overall RAS mutation prevalence of 41%. Mucinous histology had highest frequency of N-RAS mutation.
  
  
  CONCLUSIONS
  Combination of PCR HRM with either RFLP or direct DNA sequencing was useful to detect K-RAS exon 2 and extended RAS mutations, respectively. Frequency of all RAS mutations in stage IV Indonesian (41%) was similar among Asians (41-49%), which tend to be lower than western (55%) CRC.
authors.affiliation: Kalbe Genomics Laboratory, Jl. Ahmad Yani No. 2, Pulomas, Jakarta, Indonesia.
authors.forename: Michael
authors.initials: M
authors.lastname: Levi
authors.affiliation: Cancer Diagnostic, Stem-cell and Cancer Institute, Komplek Bintang Toedjoe Pulomas, Jakarta, Indonesia.
authors.forename: Gintang
authors.initials: G
authors.lastname: Prayogi
authors.affiliation: Kalbe Genomics Laboratory, Jl. Ahmad Yani No. 2, Pulomas, Jakarta, Indonesia.
authors.forename: Farid
authors.initials: F
authors.lastname: Sastranagara
authors.affiliation: Kalbe Genomics Laboratory, Jl. Ahmad Yani No. 2, Pulomas, Jakarta, Indonesia.
authors.forename: Edi
authors.initials: E
authors.lastname: Sudianto
authors.affiliation: Kalbe Genomics Laboratory, Jl. Ahmad Yani No. 2, Pulomas, Jakarta, Indonesia.
authors.forename: Grace
authors.initials: G
authors.lastname: Widjajahakim
authors.affiliation: Kalbe Genomics Laboratory, Jl. Ahmad Yani No. 2, Pulomas, Jakarta, Indonesia.
authors.forename: Winiarti
authors.initials: W
authors.lastname: Gani
authors.affiliation: Hong Kong University of Science and Technology, Hong Kong, Hong Kong.
authors.forename: Albert
authors.initials: A
authors.lastname: Mahanadi
authors.affiliation: University of Melbourne, Parkville, VIC, Australia.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Agnes
authors.affiliation: Institut Teknologi Bandung, Bandung, Indonesia.
authors.forename: Bela Haifa
authors.initials: BH
authors.lastname: Khairunisa
authors.affiliation: Cancer Diagnostic, Stem-cell and Cancer Institute, Komplek Bintang Toedjoe Pulomas, Jakarta, Indonesia. Ahmad.utomo@kalgenlab.com.
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Utomo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D007214:Indonesia / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: C117307:KRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)
keywords: Asian; Colorectal cancer mutation; High-resolution melting; Indonesia; K-RAS; N-RAS