Metastatic colorectal cancer (mCRC) is one of the most common and lethal cancers. Nextgeneration sequencing (NGS) has been recommended as a tool to help guide treatment by identifying actionable genetic mutations. However, data regarding realworld usage of NGS in a Veterans Affairs (VA) health care system is lacking. We conducted a retrospective observational study of the patterns of NGS usage in patients with mCRC at the South Texas Veterans Affairs Healthcare System (STVAHCS).
We identified patients with a diagnosis of mCRC evaluated and treated at STVAHCS between January 1, 2018 and June 1, 2022. We assessed the prevalence of utilizing NGS on solid tumor samples performed by Foundation One and identified the presence of different molecular aberrations detected by NGS.
65 patients were identified. Median age was 68 years. 63 (96.9%) were males and 2 (3.1%) were females. 29 (44.6%) were Hispanic, 25 (38.5%) were White, 10 (15.4%) were African American and 1 (1.5%) was Pacific Islander. NGS was performed in 34 (52.3%) patients. The most common reasons for not performing NGS were unknown/not documented (54.8%), early mortality (29%), lack of adequate tissue (12.9%) and patient refusal of treatment (3.2%). The most common molecular aberrations identified in patients who had NGS were TP53 (73.5%), APC (64.7%), KRAS (47.1%), ATM (20.6%), SMAD4 (14.7%) and BRAF (14.7%). All patients who had NGS were found to have at least one identifiable mutation.
Approximately 50% of patients with mCRC did not have NGS performed on their tissue sample. This rate is similar to other real-world studies in non-VA settings. Documented reasons for lack of NGS testing included inadequate tissue and early patient mortality. Other potential reasons could be lack of efficient VA clinical testing protocols, use of simple molecular testing rather than comprehensive NGS testing and limited knowledge of availability of NGS among providers. Measures that can be taken to increase utilization of NGS include incorporating NGS testing early in the disease course, incorporating testing into VA clinical pathways, improving physician education, increasing the size of solid tissue samples and ordering liquid biopsies where solid tissue is deficient.