Grail's test is a cfDNA test. It detects DNA fragments in blood that are indicative of specific methylation patterns that are in turn indicative of possible cancerous growth. While a good approach, there are continued sensitivity challenges with cfDNA tests.

This research is a high quality longitudinal retrospective study of protein cancer biomarkers, not cfDNA. Protein biomarkers are a complementary signal that has the potential to boost the sensitivity and precision of these tests, especially when the signals are combined together.