Health News Digest recently published an article that describes a simple blood test called DELFI, meaning DNA evaluation of fragments for early interception.
Its simplicity belies the fact that it can detect cancer by identifying patterns in DNA fragments that are sloughed off from malignant cells and then circulate in the bloodstream. This DNA fragmentation can be performed in the laboratory or it can happen spontaneously, meaning it happens within a cell.
In a study that tested the feasibility of DELFI, researchers found that it had an average of 73% accuracy in detecting cancer DNA. Two hundred and eight samples of blood were taken from patients from the United States, Netherlands, and Denmark with colorectal, breast, ovarian, lung, gastric, pancreatic or bile duct cancers.
The samples were taken prior to treatment. Most of the samples (183) were taken from patients who were eligible to have their tumors surgically removed.
The researchers also tested DELFI in two hundred samples of blood from healthy people. DELFI misread only four cases.
Machine Learning
DELFI uses machine learning which is an artificial intelligence application. Machine learning provides systems with the ability to perform specific tasks without being programmed for that task.
DELFI identifies abnormal patterns found in DNA fragments circulating in the bloodstream of cancer patients.
After the researchers studied these patterns, they discovered that they were able to identify the “tissue of origin” of the cancers in approximately seventy-five percent of the cases they reviewed.
A Need for Early Detection
The typical blood tests (liquid biopsies) search within a cell for changes in a DNA sequence. These tests also look for methylation, which is a chemical reaction in which a methyl group is added to DNA.
However, researchers found that existing tests are not effective in some patients because changes in these cancer patients cannot be detected by current methods. There is an urgent need to improve methods for early detection.
DELFI’s Approach
DELFI’s approach deals with the “packaging” inside the nucleus of a cell. It examines the blood for the amount and size of DNA which gives it clues to the packaging.
Dr. Alessandro Leal, the study’s lead author, describes packaging by using the analogy of a suitcase. For instance, DNA is packaged by healthy cells just as you would organize a suitcase. Different areas of the genome (full DNA sequence) are packed into various compartments.
Conversely, in cancer cells, the nuclei resemble disorganized suitcases where the areas of the genome are tossed into the suitcase haphazardly. Since the packaging of a cancer genome is not organized, when a cancer cell dies it releases its DNA into the bloodstream in a disorganized manner.
DELFI examines the DNA and recognizes cancer through detection of abnormalities in both the size and in the amount of DNA existing in areas of the genome according to the way it is packaged.
DELFI discovered that healthy individuals exhibit almost the same fragmentation profiles. Cancer patients, however, showed varied fragmentation profiles.
Researchers found that the fragmentation patterns in cancer patients result from DNA secreted from tumors and blood cells. The patterns exhibit changes in fragment sizes and multiple genomic differences.
The Future of DELFI
Additional studies are planned that are expected to provide further validation of the test. It is expected that DELFI will be used for cancer screening by simply taking a person’s blood, extracting the cell-free DNA, and determining its fragmentation profile.
The fragmentation pattern taken from individuals will be compared to reference populations (study base). It will then be determined if it is healthy or a result of cancer.
The fragmentation pattern can demonstrate the differences between certain tissues. When it is determined that the patterns are the result of cancer, the patterns can identify the origin of the cancer.
About the Genome
All human cells with a nucleus contain a genome. The entire genome consists of three billion DNA base pairs. DELFI analyzes millions of sequences in the genome and identifies tumor-specific abnormalities from very small amounts of cell-free DNA.
In addition to its other benefits, DELFI testing should be less expensive due to its ease of administration and its low-cost laboratory procedures.
