Innovative blood test may detect cancers that are otherwise hard to diagnose



A large-scale trial is ongoing to determine how the Gallieri test, as it is known, influences the time to cancer diagnosis.

Some results from the trial were recently presented at a conference.

They show a high rate of false positives but a low rate of false negatives.

The earlier cancer is detected, the more treatable it is, and the longer people are expected to survive.

National screening programs have been developed to improve cancer detection before symptoms appear, but they are not available for all cancers.

There is also some controversy over whether or not the screening programs pick up enough cancer cases for them to be worthwhile and whether they pick up too many false positive results in healthy people.

Many cancer screening tests are designed to look for a tumor in a particular organ, such as breast cancer mammographyTrusted Source screening. Some screening tests also look for a specific cancer marker from a particular organ — this is the case with the prostate-specific antigen used in prostate cancer screeningTrusted Source.

Methylation signature of cancer

Cells become cancerous when genetic mutations occur and change the expression of genes related to DNA repair, cell division, or death, and cause them to grow uncontrollably, leading to a tumorTrusted Source.

DNA in all human cells contains molecules called methyl groups, which affect how the DNA is transcribed and translated. In cancer cells, these are often different and contribute to the change in the gene expression of the cell.

Researchers also discovered in 1948 that all human cells — both cancerous and healthy ones — shed what’s called cell-free DNA into the bloodstream.

Blood tests using cell-free DNA are already used in noninvasive prenatal testing to determine whether a fetus is male or female, its blood type, or even if it has a genetic or chromosomal condition.

The use of these tests by pregnant people flagged the potential use of cell-free DNA blood tests to detect cancer when some abnormalities that turned out to be cancer in the mother were detected.

Development of the Gallieri testThe quest started to develop a blood test that could be used for cancer screening for more types of cancer using cell-free DNA.

After several years of developing the Gallieri test by the company GRAIL, in 2019, the Food and Drug Administration (FDA) received a Breakthrough Device designation for the test that looked at the methylation of cell-free DNA in the blood.

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