KRAS testing and first-line treatment among patients diagnosed with metastatic colorectal cancer using population data from ten National Program of Cancer Registries in the United States.

Abstract

Background: In 2011, the National Comprehensive Cancer Network (NCCN) recommended KRAS testing for metastatic colorectal cancer (mCRC) patients. Our study assessed KRAS testing prevalence and its association with socio-demographic and clinical factors and examined first-line treatment.

Methods: Ten state population-based registries supported by Centers for Disease Control and Prevention's (CDC) National Program of Cancer Registries (NPCR) collected detailed cancer information on mCRC cases diagnosed in 2011, including KRAS biomarker testing and first-line treatment from ten central cancer registries. Data were analyzed with Chi-square tests and multivariate logistic regression.

Results: Of the 3,608 mCRC cases, 27% (n = 992) had a documented KRAS test. Increased age at diagnosis (p < 0.0001), racial/ethnic minorities (p = 0.0155), public insurance (p = 0.0018), and lower census tract education (p = 0.0023) were associated with less KRAS testing. Significant geographic variation in KRAS testing (p < 0.0001) ranged from 46% in New Hampshire to 18% in California. After adjusting for all covariates, age and residence at diagnosis (both p < 0.0001) remained predictors of KRAS testing. Non-Hispanic Blacks had less KRAS testing than non-Hispanic Whites (OR = 0.77, 95% CI = 0.61-0.97). Among those tested and found to have normal (wild-type) KRAS, 7% received anti-EGFR treatment; none received such treatment among those with KRAS mutated gene.

Conclusions: Despite NCCN guideline recommendations, 73% of mCRC cases diagnosed in 2011 had no documented KRAS test. Disparities in KRAS testing existed based on age, race, and residence at diagnosis.

Impact: These findings show the capacity of monitoring KRAS testing in the US using cancer registry data and suggest the need to understand the low uptake of KRAS testing, and associated treatment choices during the first year since diagnosis.