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Blood tests for abnormal circulating cells are a method of future. For example a blood sample test of a pregnant woman can detect many genetic abnormalities an
by tsoukase 2y ago
Blood tests for abnormal circulating cells are a method of future. For example a blood sample test of a pregnant woman can detect many genetic abnormalities and sex of the fetus. It is based on minimal amount of DNA that can be reliably traced. The same can theoretically be done for cancerous cells if their DNA can be distinctly identified.
- _ihaque 2y agoThese are tests of circulating cell-free DNA (cfDNA), not circulating cells. The fraction of circulating _cancer cells_ is too low (outside of blood cancers or metastatic cancers) to be technically feasible to detect; ditto in pregnancy. By contrast, while there isn't much cfDNA (DNA fragments floating around in blood plasma outside of cells) -- on the order of 1-10 ng/mL -- there's enough to extract reliably, and critically, the fraction of that that is tumor-derived (or fetally-derived, for prenatal testing) can be high. It's already high single to low double digit percent at 10-12 weeks of gestation, and can go much higher in some cancers. But the biggest challenge for these tests is that this "tumor fraction" can be very very low in early stage cancers, which is why stage I sensitivity tends to be quite poor.
- tsoukase 2y agoThere is long time to go until a useful "cancer biomarker", sadly. Cancer is a stubborn problem.