Aug. 16 (UPI) -- University of California San Diego School of Medicine researchers have identified targetable genetic alterations in patients with a rare cancer using biopsies of the blood.
Blood or liquid biopsies can detect the onset of disease, monitor progression and measure any weakening with just one vial of blood.
The biopsies were able to identify genetic alterations in 66 percent of patients with cancer of unknown primary, or CUP, a rare type of cancer occurring in 7 to 12 per 100,000 people each year.
The study, published in the August edition of Cancer Research, showed that in CUP, the origin of the cancer is unknown even though the cancer may have spread throughout the body. This makes CUP difficult to treat.
The current standard to treat CUP is a combination of chemotherapies with a median survival of six to eight months.
"By definition, CUP does not have a definite anatomical diagnosis, but we believe genomics is the diagnosis," Dr. Razelle Kurzrock, director of the Center for Personalized Cancer Therapy at Moores Cancer Center at UC San Diego Health, said in a press release.
"Cancer is not simple and CUP makes finding the right therapy even more difficult. There are multiple genes and abnormalities involved in different areas of the body. Our research is the first to show that evaluating circulating tumor DNA from a tube of blood is possible in patients with CUP and that most patients harbor unique and targetable alterations."
Researchers sequenced circulating tumor DNA, or ctDNA, from blood samples of 442 patients with CUP, and were able to identify at least one genetic alteration linked to cancer in 290 patients. They used the Guardant Health screening test, which evaluates up to 70 genes at a time.
"What we saw was that the patient was responding to treatment, but the cancer had emerging new mutations," Kurzrock said. "What's new here is that we can do the same evaluation through a blood test that we previously could only do with a tissue sample. You will see these changes with a simple blood test and it is easy to repeat blood tests, but hard to repeat tissue biopsies."
Researchers found that 99.7 percent of the 290 patients with detectable tumor DNA in their blood had genomic alterations that could be targeted using existing Food and Drug Administration-approved drugs or therapies under clinical trials.