The Lynx Group

No Clear Selection Criteria for Genomic Testing in Patients with Metastatic Colorectal Cancer

October 2016, Vol 7, No 9

Washington, DC—The use of gene panels to guide decision-making in patients with metastatic colorectal cancer (mCRC) has no clear association with patient characteristics, according to the results of a preliminary single-center study presented at a poster session at the 2016 International Society for Pharmacoeconomics and Outcomes Research annual meeting.

Patients whose tumors were evaluated by next-generation sequencing gene panels had clinical and demographic characteristics similar to those of patients whose tumors were evaluated for KRAS mutation status. Year of diagnosis for metastatic disease proved to be the only predictor of next-generation sequencing testing.

“Clinicians are adopting this practice [next-generation sequencing testing] to guide clinical decisions regardless of mCRC patients’ characteristics,” Eman Biltaji, PhD candidate, a graduate research assistant at the University of Utah, Salt Lake City, and colleagues noted.

The National Comprehensive Cancer Network recommends routine testing for KRAS mutation status for patients with newly diagnosed mCRC to identify those eligible for treatment with an EGFR inhibitor, the standard of care for KRAS-positive tumors. Recent evidence suggests the possible existence of multiple mutations in patients with mCRC that are amenable to treatment with targeted agents.

Genomic profiling using technology that includes next-generation sequencing panels has the potential to identify multiple targetable mutations in a single test, eliminating the need for multiple tests for individual mutations, according to the investigators. Understanding factors associated with the use of next-generation sequencing testing can inform efforts to make efficient use of the technology

Study Details

To identify factors associated with use of next-generation sequencing testing in patients with mCRC, Ms Biltaji and colleagues analyzed data from electronic health records and the University of Utah Huntsman Cancer Institute Tumor Registry. Patients with newly diagnosed stage IV mCRC from January 1, 2010, through April 10, 2015, were identified.

By means of codes associated with the tests, the investigators identified patients for whom next-generation sequencing or KRAS testing was performed.

Data analysis included 140 patients who had testing only for KRAS mutations, and 59 patients who had testing with next-generation sequencing and did or did not undergo testing for KRAS mutations.

The results showed that the frequency of next-generation sequencing testing increased from 1.7% of patients with newly diagnosed mCRC tumors in 2010 to 71.2% in 2014. However, most of the increase occurred from 2013 (8.5%) to 2014. The proportion of mCRC tumors tested for KRAS mutations decreased from 25.0% in 2010 to 4.3% in 2014; as with the increase in next-generation sequencing testing, most of the decrease occurred from 2013 (21.4%) to 2014.

A comparison of baseline characteristics for patients with KRAS testing only and those who had next-generation sequencing testing showed no significant differences with respect to patient age at diagnosis of mCRC, sex, race, stage at initial diagnosis, number of metastatic sites, sites of metastatic disease, time from initial diagnosis to mCRC, or time from mCRC diagnosis to genetic testing.

In a multivariable analysis, the year of the patient’s mCRC diagnosis was the only factor that had a significant association with the likelihood of next-generation sequencing testing. As compared with 2010, the odds ratio favoring next-generation sequencing testing increased from 2.41 to 5.83 for the years 2011 through 2013, but none of the differences achieved statistical significance. In contrast, patients with newly diagnosed mCRC had an odds ratio favoring next-generation sequencing testing of 250.83 in 2014 versus 2010.

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