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Mismatch Repair/Microsatellite Instability Biomarker Testing Utilization in Advanced Colorectal Cancer
In 2017, DNA mismatch repair/microsatellite instability (MMR/MSI) testing was nationally recommended for advanced colorectal cancers based on favorable immune checkpoint inhibitor responses among patients with MMR-deficient/MSI-high tumors.
Findings from a recently study revealed opportunities for enhancing rates of MMR/MSI testing and reporting, possibly by way of integration into quality control and accreditation metrics (Cancer Epidemiol Biomarkers Prev. 2022;31(9):1746-1751. doi:10.1158/1055-9965.EPI-22-0279).
David J Papke, Jr, MD, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, and colleagues used data from the National Cancer database to identify patients ages ≥20-years-old presenting with stage IV colorectal adenocarcinoma from 2010 to 2017. Patient, tumor, socioeconomic, and care setting characteristics were assessed for association with upfront MMR/MSI testing in 2017 using multivariable logistic regression and average adjusted predicted probabilities (%AAP).
Among 72,830 patients with stage IV colorectal cancers, upfront MMR/MSI testing levels increased from 16.4% in 2010 to 56.4% in 2017. For patients diagnosed in 2017 (i.e., following national recommendations, n = 10,022), testing levels were lower for older patients (Padj < 0.001), and were independent of patients' race/ethnicity and insurance status.
Patients from the poorest quartile of households received less testing [49.6%AAP, 99.9% confidence interval (CI) 45.5-53.7] than patients from the 3rd (56.9%AAP, 99.9% CI, 53.3-60.6; Padj < 0.001) or 4th quartiles (57.6%AAP, 99.9% CI, 54.3-60.9; Padj < 0.001). Although testing levels improved most at community programs, they remained lower in 2017 (46.6%AAP, 99.9% CI, 41.0-52.1) compared with academic/NCI-designated comprehensive cancer centers (62.8%AAP, 99.9% CI, 59.7-65.8; Padj < 0.001).
“Upfront MMR/MSI testing utilization for patients with advanced colorectal cancer has increased but there is still substantial need for optimization,” wrote Dr Papke and colleagues, concluding, “Testing utilization disproportionately lagged for patients who were older, from the poorest quartile of households, or managed at community cancer programs.”
