A low-cost blood test could help catch cancers mammograms miss in dense breasts
A whole blood RNA test could screen women with dense breasts at a lower lifetime cost, and with marginally better projected health outcomes, than mammography alone.
An exploratory economic analysis published online July 25 in Clinical Breast Cancer used a lifetime Markov model to compare three biennial screening strategies starting at age 40: mammography alone, the blood test alone, and the two combined.
Researchers measured lifetime costs, life-years and quality-adjusted life-years (QALYs) for each pathway.
Modelling put the blood-test-only pathway at a lifetime cost of US$21,642 and 18.78 QALYs per person, the authors report, against US$26,852 and 18.67 QALYs for mammography alone.
Because mammography alone cost more and produced fewer QALYs, the analysis classed it as "dominated."
Adding mammography to the blood test raised costs for a small gain, generating an incremental cost-effectiveness ratio (ICER) of US$169,385 per QALY, above the US$100,000 to US$150,000 per QALY the study cites as standard US willingness-to-pay thresholds.
The authors stress the findings are exploratory and hypothesis-generating.
The test remains under clinical validation, they note, and no clinical utility or real-world performance results have been published; stage-shift, adherence and mortality benefits were estimated from preliminary data rather than demonstrated.
Cost sits at the centre of the case.
The model assumed a blood test price of US$512, set equal to the US Medicare payment for the Cologuard colorectal screening test.
Syantra Inc., whose staff co-authored the analysis alongside University of Calgary academics, said rival blood tests entering the market can cost upwards of US$3,000.
The modelled test uses 15 RNA transcripts measured by multiplex quantitative PCR with machine-learning software, and detects the body's response to a tumour rather than cancer-derived material.
Women with dense breasts make up about half of the screening-age population and tend to have cancers masked on mammography.
It drew mammography sensitivity of 39.1 percent for dense breasts from a 2020 comparison study, against interim results for the blood test of 79.2 percent sensitivity and 94.3 percent specificity.
The model also assumed higher participation for blood testing, drawing on colorectal and prostate screening evidence; measured against a population that does not screen at all, biennial blood testing cut per-patient costs by US$5,987 and improved QALYs by 0.194, the analysis found.
The study set out to test how a blood-based test might fit into breast screening pathways, said Eldon Spackman, an associate professor at the University of Calgary and a co-senior author.
The results point to the test as a complement to mammography or an option for those not screening regularly, he said.
Rob Lozuk, Syantra's chief executive officer, said detection timing is the core problem.
The main challenge is "finding cancer when it is most treatable," he said, which remains unmet for millions of women.
Lozuk said the company plans real-world testing through early access programs pairing blood testing with imaging in higher-risk women and those who do not screen regularly.
The study provides "an early framework" for how blood-based screening could fit into future breast cancer pathways, especially for women with dense breasts, said Edith Perez, a professor emeritus at the Mayo Clinic.
