New Blood-Based Liquid Biopsy Holds Potential as Alternative for Invasive Tumor Biopsy

A new FDA-approved blood-based genetic test suggests that a simple blood test, dubbed as liquid biopsy, can detect possible gene mutations of cancer DNA with the same accuracy as the traditional invasive tumor biopsy.

"These findings suggest that analysis of shed tumor DNA in patient blood, also known as a liquid biopsy, can be a highly informative, minimally-invasive alternative when a tissue biopsy is insufficient for genotyping or cannot be obtained safely," said study presenter Philip Mack, PhD, Professor and Director of Molecular Pharmacology at the University of California Davis Comprehensive Cancer Center, in a statement.

At present, medical practitioners extract a piece of the tumor using a needle or surgery to monitor the mutations of cancer genes. Tumor biopsies have complications due to its invasive nature and at some circumstances, cannot be done repeatedly. On the other hand, liquid biopsies only require a simple blood test to search and analyze circulating tumor DNA (ctDNA) shed by tumor cells into the bloodstream.

The study, to be presented at the 2016 ASCO Annual Meeting, involves 15,191 patients with advanced lung cancer, breast cancer, colorectal cancer and other kind of cancer. The researchers assessed the accuracy of the liquid biopsies by comparing the patterns of genomic changes in ctDNA to the 398 available tumor biopsy results. The researchers discovered that if a particular mutation that drive tumor growth was found in the blood it was also present in the tumor biopsy about 94 to 100 percent of the time.

However, there are some mutations that can't be detected using the liquid biopsy. In particular, patients with glioblastoma, the most common and most aggressive kind of brain cancer, have a lower chance of mutation detection using liquid biopsy. Researchers believe that this shortcoming of the liquid biopsy is due to the blood-brain barrier, making it more difficult for the ctDNA from a brain tumor to enter the bloodstream.

Researchers believe that periodic monitoring of the disease progression, response to therapy, and development of treatment resistance using liquid biopsy can greatly help doctors in adjusting the treatment plan of their patients. But, the researchers noted that tumor biopsy is still better for early cancer diagnosis.