Clinical relevance of the K-ras oncogene in colorectal cancer: Experience in a Mexican population

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. Aims: 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 Institute 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 65 years, 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. (C) 2013 Asociacion Mexicana de Gastroenterologia. Published by Masson Doyma Mexico S.A. All rights reserved.