KRAS mutation profile in Puerto Rican patients with colorectal cancer: Trends in expression of KRAS mutation in PR between April 2009 to January 2011.

Abstract

e14102 Background: The prevalence of a mutated KRAS gene in colorectal cancer shows ethnic variation with a range between 30-48% among the Caucasian, Asian, and European populations. The purpose of this study was to define the profile of KRAS mutation in colorectal cancer patients in Puerto Rico. Methods: Between April 2009 and January 2011, we collected the expression of KRAS gene among colorectal cancer patients in Puerto Rico. The assay was performed by a central laboratory which began to offer the test in the island in April 2009 (GENOPTIX). Data for the presence and type of mutation, age, sex, cancer histology, site of tumor, and cancer stage were collected. The site of the mutation in codon 12 and 13 were identified by the real time polymerase chain reaction (PCR). The study was approved by IRB. A total of 501 cases were available for study. SPPS version 14 was used for statistical analysis. Results: A mutated KRAS was present in 39% (n=195) of the cohort, more commonly in the 51-69 age group (55.4%; p=0.004), in females (55.4%; p=0.095), in the proximal area of colon (43.8%; p=0.017), in the codon 12 (91.2%), and 8.8% in the codon 13. The majority of mutated genes were in codon 12 (91.2%) with 12 ASP (39.5%) and 12 VAL (25.4%) most often seen. Mucinous histology was associated with 46.7% mutated KRAS, poorly differentiated tumor with 40.0% of KRAS mutation. The mutant expression of KRAS in cases with rectum carcinoma was 39.5%, where the most common mutation was 12 VAL. Conclusions: The prevalence of KRAS mutation in Puerto Rican population is similar to other reported studies. A higher prevalence of 12 VAL mutation in rectal carcinoma and a trend towards a higher mutation rate in females are different in this cohort as compared with published studies. This study was supported by NIH grant numbers G12RR-03035 & 8U54MD007587-03.