Vigilance in detecting tumor mutations in prostate cancer by liquid biopsy: in a trial of 69 men, half were false positives.
- Liquid biopsy can detect cancer through a simple blood test
- This method can lead to confusion between a mutation present in a blood disease and a tumor mutation in prostate cancer
- This confusion can lead to the prescription of unnecessary treatments.
Liquid biopsy transforms the diagnosis of cancer: thanks to a simple blood test, scientists can detect the presence of a tumour. This method also allows them to analyze the evolution of cancer in a patient treated. A study from the University of Washington, however, calls for vigilance: these examinations can create false positives, that is to say that the test will indicate the presence of a genetic mutation of the tumor, whereas it does not ‘there is not any. In a study of men with prostate cancer, researchers found that half of the patients were false positives. This research from the University of Washington was published in JAMA Oncology.
Similar genetic mutations
Liquid biopsy consists of analyzing the blood to detect cancer or identify its evolution. “You can assess a patient’s tumor with a blood draw.”, summarizes Colin Pritchard, associate professor at the School of Medicine at the University of Washington. Genetic mutations are detectable through the DNA of the tumor present in the blood. In patients already treated for cancer, this examination makes it possible to adapt the treatments, according to the evolution of the tumour. In some cases, genetic mutations present in the blood can mislead researchers: they have no connection with the tumor but their DNA is similar. Mutations in the BRCA1, BRCA2 and ATM genes are linked to cancer, but also to clonal hematopoiesis, a pathology of the blood.
Half of false positives
In research carried out on 69 men, American scientists wanted to understand to what extent this pathology could be confused with a mutation in a prostate tumor. Of all the blood biopsies performed, almost half of the genetic mutations observed were linked to clonal hematopoiesis. The older the patients, the more frequently these variations were present. These false positives worry the researchers, because since the spring, two drugs have been authorized in the treatment of prostate cancer in the United States. If the biopsy is positive, they are among the possible therapies. For false positives, it would be a useless and ineffective treatment.
A necessary double check
For the research team, it is necessary that there is a double control in case of blood biopsy, to verify that it is not a clonal hematopoiesis. “The good news is that by looking at how blood cells are compartmentalized, you can tell whether it’s cancer or hemopoiesis with some degree of certainty.”concludes Colin Pritchard.
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