KRAS testing of patients with metastatic colorectal cancer in a community-based oncology setting: a retrospective...

In 2009, treatment guidelines were updated to recommend KRAS testing at diagnosis for patients with metastatic colorectal cancer (mCRC). We investigated KRAS testing rates over time and compared characteristics of KRAS-tested and not-tested patients in a community-based oncology setting.

Adult patients with a diagnosis of mCRC from 2008-2011 were selected from the ACORN Data Warehouse (ACORN Research LLC, Memphis, TN). Text mining of physician progress notes and full chart reviews identified KRAS-tested patients, test dates, and test results (KRAS status). The overall proportion of eligible patients KRAS-tested in each calendar year was calculated. Among KRAS-tested patients, the proportion tested at diagnosis (within 60 days) was calculated by year. Univariate and multivariate analyses were used to compare patient characteristics at diagnosis between tested and not-tested cohorts, and to identify factors associated with KRAS testing.

Among 1,363 mCRC patients seen from 2008-2011, 648 (47.5%) were KRAS-tested. Among newly diagnosed mCRC patients, the rate of KRAS testing increased from 5.9% prior to 2008, to 13.9% in 2008, and then jumped dramatically to 32.3% in 2009, after which a modest yearly increase continued. The proportions of KRAS-tested patients who had been diagnosed in previous years but not tested previously increased from 17.7% in 2008 to 27.0% in 2009, then decreased to 19.0% in 2010 and 17.6% in 2011. Among patients who were KRAS-tested, the proportions tested at the time of diagnosis increased annually (to 78.4% in 2011). Patients more likely to have been tested included those with lung metastases, poor performance status, more comorbidities, and mCRC diagnosis in 2009 or later.

The frequency of KRAS testing increased over time, corresponding to changes in treatment guidelines and epidermal growth factor receptor inhibitor product labels; however, approximately 50% of eligible patients were untested during the study period.