Real-world genetic testing patterns in metastatic colorectal cancer: Balancing adoption challenges with performance efficiency.

46 Background: Evaluation of real-world data regarding genetic testing for metastatic colorectal cancer (mCRC) highlights the successes and challenges of precision medicine. Guidelines recommend genetic testing to inform mCRC treatment choice. However, there is a lack of real-world evidence regarding genetic testing patterns, including adoption and efficiency. Methods: This retrospective analysis identified adult patients with newly diagnosed mCRC (2015-2106), Medicare Advantage coverage with a pharmacy benefit (MAPD), and claims evidence of CRC-related genetic testing. Inclusion required diagnosis of colon/rectal cancer on ≥2 medical claims and new metastatic disease. Paid and unpaid claims identified genetic testing, which was classified as limited RAS, extended KRAS/NRAS, limited + extended, and BRAF. Efficiency was measured as time-to-testing and time-to-treatment once testing was performed. Results: The study included 4,408 patients with mCRC and MAPD, with a median age of 72 years. Evidence of limited +/- extended testing was noted for 667 (15.1%) of patients. Of these, 78.3% initiated CRC treatment. Limited, extended, and limited + extended testing was observed for 51.7%, 4.5% and 43.8% of patients, respectively. BRAF was observed for 46.4%, 23.3% and 63.7% of patients with limited, extended, or limited + extended testing, respectively. For the 69.2% of patients tested prior to treatment, the median number of days between mCRC diagnosis and first genetic test was 6 [range: 0-31] days, with 25 [13-46] days between testing and treatment. When treatment preceded testing, the median number of days from treatment to test was 72.0 [20-251]. Of patients with > 1 genetic test, most patients had all tests on the same day (96.9%) or within 7 days (97.8%) of diagnosis, with no differences by type of testing. Conclusions: Per guidelines, mCRC-related genetic testing was completed efficiently after diagnosis and prior to treatment initiation for most patients. Genetic testing rates remain low, perhaps indicating barriers to scaling precision medicine. Ongoing research to explore ways to expedite adoption of precision medicine, while maintaining its efficiency, is needed.