Demographic factors on the incidence of KRAS mutation in colorectal cancers.

Abstract

e14040 Background: KRAS mutation status in colorectal cancers (CRCs) is predictive of response to anti-epidermal growth factor receptor therapies, such as cetuximab and panitumimab. Our objective was to determine the demographic factors on KRAS mutation status among patients with CRC seen at Washington University in St. Louis. Our secondary objective was to examine survival of patients stratified by age, race, disease location, and mutation status. Methods: A retrospective review of 271 patients on the CRC registry at Washington University was done between 1/17/07 and 12/18/09. All patients had KRAS mutational analysis. Patients with mutations to codons 12 or 13 were considered mutated. Others were considered wild-type. Age, sex, race, and location of primary tumor were examined for correlation with the rate of KRAS mutations. Survival was measured from the date of metastatic disease diagnosis to the date of death. Results: Patient cohort: Median age 58 (24–94), 20% AAs, 54% males. The overall rate of KRAS mutations was 43.5%. We found no significant association between KRAS mutation status and age or sex. The KRAS mutation rate among AAs (47%) was relatively higher than among Caucasians (43%). The KRAS mutation rate in colon cancers (46%) was higher than that in rectal cancers (37%). Median and overall survival statistics are preliminary; 76% of patients are still alive. However, overall survival is higher for wild type patients in all groups. Conclusions: In this single-institution retrospective study, KRAS mutation rates appear to be higher among AA patients and patients with colon, rather than rectal, primaries. Colorectal cancer patients with KRAS mutation have less therapeutic options than those with wild-type tumors. Thus, the difference in KRAS mutation rates among AA and Caucasians may, in part, elucidate factors contributing to worse outcomes among AA patients with colorectal cancers. Similarly, the higher rate of KRAS mutation in colon versus rectal tumors may contribute to worse prognoses. Mutated Nonmutated Median survival (days) Total (n) Age >= 50 43% 57% 614 203 < 50 44% 56% 577.5 68 Sex Male 43% 57% 565 145 Female 44% 56% 625.5 126 Race AA 47% 53% 573 55 Caucasian 43% 57% 617.5 210 Location Rectal 37% 63% 626 84 Colon 46% 54% 599 187 No significant financial relationships to disclose.