A study has found that a simple blood test is enough to detect gene mutation that occurs in patients with lung cancer.
Researchers from Dana-Farber Cancer Institute and Brigham and Women's Cancer Center (DF/BWCC) reported that liquid biopsy has good reliability in identifying changes in two important genes in non-small cell lung cancer (NSCLC). This finding shows that the biopsy would be an excellent clinical tool for assessing patients who will benefit from drugs that prevent such mutations.
The liquid biopsy, also known as rapid plasma genotyping, is done by taking a test tube filled with blood that has free-floating DNA from cancer cells. The blood was subjected to DNA analysis to look for mutations and other abnormalities. Mutations can be detected in the blood because when tumor cells die, their DNA spills into the bloodstream and they become cell-free DNA.
The above-mentioned procedure, frequently done by researchers to study the molecular make up of a variety of cancers, allows experts to identify presence of any key genetic irregularities in a tumor.
Senior study author Dr. Geoffrey Oxnard said that plasma genotyping can be used as a noninvasive way of cancer screening. Genetic footprints can be identified without having to subject patients to traditional invasive biopsies.
"Our study was the first to demonstrate prospectively that a liquid biopsy technique can be a practical tool for making treatment decisions in cancer patients," said Oxnard.
The study involving 180 patients compared liquid biopsies with conventional tissue biopsy to test for the same epidermal growth factor receptor (EGFR) and KRAS mutations. Results showed that liquid biopsies has faster turnaround time of three days compared with the 12-day and 27-day period of tissue biopsies for newly diagnosed and drug-resistant patients, respectively.
Liquid biopsies also showed higher accuracy with a predictive value of 100 percent for newly diagnosed patients and 79 percent for those with drug resistance mutations, which suggests that the blood test was able to identify new cases of gene mutations that were not seen during standard biopsies.
Liquid biopsies allow doctors to immediately assess if the patient is responding to the medication or not.
"It's fast, it's quantitative (it indicates the amount of mutant DNA in a sample), and it can be readily employed at a cancer treatment center," said DF/BWCC pathologist Lynette Sholl.
The study was published on the Journal of American Medical Association Oncology.
According to the American Cancer Society, NSCLC remains as the most common lung cancer form affecting over 200,000 people in the United States annually. About 30 percent of patients diagnosed with NSCLC have genetic mutations that often respond to targeted therapies.
Just last month, the Food and Drug Administration (FDA) approved Pfizer's Xalkori (crizotinib) as treatment for patients with advanced non-small cell lung cancer with ROS1 gene mutation.
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