Plasma may have changes in DNA that could flag cancer several years before existing diagnostic testing. This is a hint from early research.
A recent study, published May 22 in the journal Cancer Discovery, found traces of free-proliferating DNA from dead pre-cancer cells or cancer cells in plasma donated three years before diagnosis.
“This is an important step towards preclinical cancer detection, which could potentially revolutionize cancer screening,” said Catherine Alix Panaviere, a cancer researcher at the University of Montpellier in France, who was not involved in the work. “Previous detections usually correlate with better outcomes for more cancer types with previous interventions,” she told Live Science in an email.
You might like it
The prognosis for cancer patients is generally worsened, but the illness is then arrested. Especially when it grows and spreads to other organizations. However, tumor-causing genes alter genes or mutations that tend to appear decades ago. Dr. Yuxuan Wang, a consultant oncologist at Johns Hopkins University, and her colleagues wanted to see if tumor DNA could be detected in plasma long before cancer appeared.
They examined plasma (the liquid in which blood cells are suspended) collected from patients about 40 years ago for unrelated studies. They focused on 26 participants who developed cancer within six months of donating blood, and 26 controls who did not develop cancer after at least 17 years of control.
Related: Simple blood tests can become the future of cancer diagnosis
Wang’s group discovered 1-3 common cancer mutations in seven plasma samples. All of these were taken from participants who developed cancer within four months of donating blood.
Six of these patients had donated blood from 3.1 to 3.5 years ago, so Wang’s team even backed the clock and evaluated these previous samples for the same mutation. Two of the early samples contained the same DNA error, and in at least some people we confirmed that these warning signs were detectable several years before the tumor appeared.
As only a few common mutations have been discovered in two of the six plasma samples taken three years before diagnosis, plasma DNA was sequenced to find additional mutations unique to each patient. Using the genome of those leukocytes, a type of immune cells, as a reference, we discovered 4-90 unique mutations in plasma DNA from three patients. They said they found cancer hints in three of the five early samples they looked at.
The patients in this study suffered from a variety of cancers, including breast, colon, liver, lung, pancreas and rectal cancers. However, it is not clear whether the testing method works equally for all tumor types. “Some organs run more tumor DNA than others,” Wang told Live Science, saying that the barrier to the blood-brain, a protective membrane, could prevent organs from entering the bloodstream.
Furthermore, the new study found no cancer DNA in 18 of the 26 participants who developed tumors in the months after the samples were collected. It is not ideal for clinical testing, Wang said. However, she suggested that detection could potentially improve if doctors ingest more plasma from each patient.
This test could help preemptively screen patients one day, as they could detect cancer a few years before symptoms first appear. However, further experiments are needed to ensure that this diagnosis does not result in false positive results, which can lead to unnecessary warnings on patients and possibly lead to unnecessary treatment or invasive diagnostic procedures, such as biopsies.
“Ethically, implementing such tests in everyday screening requires clear guidelines on how to handle accidental findings,” said Alix-Panabières.
Additionally, since the study only includes 52 plasma samples, a large study with hundreds or even thousands of participants will be required to validate the test before physicians can use it with confidence. “Realistically, widespread clinical recruitment can take another five to ten years,” predicted Alix-Panabières.
Finding personalized mutations requires a sequence of the patient’s DNA, which can cost hundreds or even thousands of dollars, Wang said. So, even if such a test is validated in a large-scale trial, it may need to be booked, for example, in groups at risk whose families know about cancer history, “probably not something we can offer to everyone we want to screen.”
Recent studies consisted mainly of black and white men and women between the ages of 45-64 in four US states. Future research can explore the efficiency of testing people from other genetically diverse backgrounds.
This article is for informational purposes only and is not intended to provide medical advice.
Source link
