Background: National Comprehensive Cancer Network guidelines have recommended metastatic colorectal cancer patients (mCRC pts) undergo BRAF, KRAS, NRAS, and microsatellite instability/mismatch repair deficiency (MSI/MMR) testing since 2015. Previous studies have reported molecular testing rates from academic and community cancer centers, but there is a lack of information on testing rates in community health systems (HS) which account for approximately half of US cancer care.

Methods: Tumor molecular testing rates were assessed in a first stage analysis for pts with mCRC in HS, in order to inform a second stage analysis focused on treatment decisions and pt outcomes. For the first stage analysis, we randomly selected 200 pts (50 pts from each of 4 HS sites) diagnosed with mCRC between 1/1/2015 and 9/1/2020. The 200 pts were identified through technology-enabled curation, followed by retrospective review performed by certified tumor registrars. An anticipated cohort of 1000 evaluable pts is planned for the second stage analysis.

Results: 53% of pts were tested for all four biomarkers at some point during their care (Table). Pts more likely to have been tested include those: from HS Site 1 (P = 4.2x10-5); age <65 years old at mCRC diagnosis (P = 0.014); and with commercial insurance (P = 0.015). Among pts tested, the median times from metastatic diagnosis to BRAF, KRAS, and NRAS testing results were 35, 33, and 34 days, respectively.

Conclusion: This first stage analysis of molecular testing in mCRC pts revealed variation in testing rates by site, biomarker, and patient characteristics, which may in part be explained by the implementation of a precision medicine testing program at HS Site 1. A second stage analysis assessing the impact of biomarker testing on treatment decisions and pt outcomes will be guided by this initial characterization of testing rates and possible confounders.

Biomarker testing rates among metastatic colorectal patients across four health system sites

Site 1 (n=50)Site 2 (n=50)Site 3 (n=50)Site 4 (n=50)
BRAF tested 43 (86%) 25 (50%) 24 (48%) 26 (52%) 
Count (%)     
KRAS tested 44 (88%) 35 (70%) 32 (64%) 35 (70%) 
Count (%)     
NRAS tested 42 (84%) 23 (46%) 26 (52%) 30 (60%) 
Count (%)     
MSI/MMR tested 49 (98%) 37 (74%) 44 (88%) 44 (88%) 
Count (%)     
All biomarkers tested 40 (80%) 19 (38%) 20 (40%) 26 (52%) 
Count (%)     
Site 1 (n=50)Site 2 (n=50)Site 3 (n=50)Site 4 (n=50)
BRAF tested 43 (86%) 25 (50%) 24 (48%) 26 (52%) 
Count (%)     
KRAS tested 44 (88%) 35 (70%) 32 (64%) 35 (70%) 
Count (%)     
NRAS tested 42 (84%) 23 (46%) 26 (52%) 30 (60%) 
Count (%)     
MSI/MMR tested 49 (98%) 37 (74%) 44 (88%) 44 (88%) 
Count (%)     
All biomarkers tested 40 (80%) 19 (38%) 20 (40%) 26 (52%) 
Count (%)     

Citation Format: Chenan Zhang, Mahder Teka, Francesca F. Coutinho, Joseph R. Burkhart, Louise E. Widmer, Ronda G. Broome, Mary T. Tran, Michael A. Thompson, Antony M. Ruggeri, Jennifer J. Godden, James L. Weese, Douglas J. Reding, Anna B. Berry, Yanina Natanzon, Thomas D. Brown. Staged analysis of standard of care tumor molecular testing among patients with metastatic colorectal cancer in the community health system setting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2618.