KRAS testing disparities in the state of New Mexico.

Abstract

551 Background: ASCO guidelines published in 2009 recommend all patients with metastatic colorectal cancer (CRC) receive KRAS testing to guide anti-EGFR monoclonal antibody treatment. Recent literature examining nation-wide trends via the Surveillance, Epidemiology, and End Results (SEER) database showed New Mexico to exhibit the highest KRAS rates of testing out of 18 registries. We aim to explore disparities in KRAS testing in the state of New Mexico. Methods: The New Mexico Tumor Registry (NMTR), a population-based cancer registry participating in the SEER Program, was queried to identify all incident cases of CRC among New Mexico residents from 2010 to 2013. Chi-square tests were used to identify disparity in KRAS testing with a p-value ≤ 0.05 considered significant. Results: A total of 637 patients were diagnosed with metastatic CRC from 2010-2013. As expected, KRAS testing in Stage 4 patients presented the highest frequency (38.4%), though testing in stage 3 (8.5%), stage 2 (3.4%) and stage 1 (1.2%) was also seen. In those with metastatic disease, younger patients (ages 22-39 and 40-64 years) were more likely to receive testing than patients 65 years and older (p < 0.0001). Patients living in or near a metropolitan center received KRAS testing more often than patients living in non-metro and rural areas (p = 0.016). There were no disparities in testing between male and female patients (39.1 v. 37.7%; p = 0.71) or amongst the predominant ethnic groups (p = 0.66). A small increase in the occurrence of KRAS testing was noted from 2010 to 2013 (34.2 to 42.2%); this trend approached though did not obtain significance (p = 0.07). In stage 4 patients, there were no significant differences in rates of wild-type versus mutant status when examined by age (p = 0.95), sex (p = 0.41), ethnicity (p = 0.41), by progressive years (p = 0.42) or geography (p = 0.35). Conclusions: New Mexico exhibits high rates of KRAS biomarker testing in patients with metastatic CRC. Age and geographic disparities exist in the rates of testing, while sex, ethnicity and the year tested showed no differences. Further study is required to explore the reasons for this disparity in KRAS testing, as well as to determine the motivation for testing in stage 1 through 3 CRC which is contrary to current treatment guidelines.