title: [Clinical relevance of the K-ras oncogene in colorectal cancer: experience in a Mexican population].
abstract: BACKGROUND
  Colorectal cancer is frequent in the developed countries, with a cancer-specific mortality rate of 33%. Different biomarkers are associated with overall survival and the prediction of monoclonal treatment effectiveness. The presence of mutations in the K-ras oncogene alters the response to target therapy with cetuximab and could be an independent prognostic factor.
  
  
  OBJECTIVE
  To analyze the difference in survival between patients with mutated K-ras and those with K-ras wild-type status.
  
  
  METHODS
  Thirty-one clinical records were retrospectively analyzed of patients presenting with colorectal cancer that underwent K-ras sequencing through real-time polymerase chain reaction within the time frame of 2009 to 2012 at the Hospital de Alta Especialidad de Veracruz of the Instituto para la Salud y Seguridad Social de los Trabajadores del Estado (HAEV-ISSSTE). Survival analysis for patients with and without K-ras mutation was performed using the Kaplan Meier method. Contrast of covariates was performed using logarithmic transformations.
  
  
  RESULTS
  No statistically significant difference was found in relation to survival in the patients with mutated K-ras vs. those with K-ras wild-type (P=.416), nor were significant differences found when analyzing the covariants and survival in the patients with mutated K-ras: ECOG scale (P=.221); age (less than, equal to or greater than 65years, P=.441); clinical stage according to the AJCC (P=.057), and primary lesion site (P=.614).
  
  
  CONCLUSIONS
  No relation was found between the K-ras oncogene mutation and reduced survival, in contrast to what has been established in the international medical literature. Further studies that include both a larger number of patients and those receiving monoclonal treatment, need to be conducted. There were only 5 patients in the present study that received cetuximab, resulting in a misleading analysis.
authors.affiliation: Facultad de Medicina, Universidad Veracruzana, Veracruz, México. Electronic address: cabrera_md@icloud.com.
authors.forename: F
authors.initials: F
authors.lastname: Cabrera-Mendoza
authors.affiliation: Departamento de Medicina Interna, Oncología Médica, Hospital de Alta Especialidad de Veracruz, Instituto para la Salud Seguridad Social de los Trabajadores del Estado (ISSSTE), Veracruz, México.
authors.forename: S
authors.initials: S
authors.lastname: Gainza-Lagunes
authors.affiliation: Facultad de Medicina, Universidad Veracruzana, Veracruz, México.
authors.forename: I
authors.initials: I
authors.lastname: Castañeda-Andrade
authors.affiliation: Facultad de Medicina, Universidad Veracruzana, Veracruz, México.
authors.forename: A
authors.initials: A
authors.lastname: Castro-Zárate
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000401:mortality*; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D008297:Male; D008800:Mexico; D008875:Middle Aged; D009154:Mutation; D012189:Retrospective Studies; D015996:Survival Rate
keywords: Colon cancer; Cáncer colónico; K-ras mutations; Mutaciones K-ras; Supervivencia; Survival