June 2015, Vol 4, No 3
DNA Blood Testing May Be an Alternative to Tumor Sampling for Identifying EGFR Mutations
Circulating cancer DNA in the blood of cancer patients appears to be able to provide information similar to that obtained from tumor tissue sampling, according to a study presented at the European Lung Cancer Conference. This makes blood testing for DNA an attractive option in cases where tumor tissue is not available.
These results have important implications for selection of targeted therapies aimed at specific cancer mutations, said presenting author Martin Reck, MD, Department of Thoracic Oncology at Lung Clinic Grosshansdorf, Germany.
There are circumstances where it is difficult, if not impossible, to obtain tumor tissue for genetic testing, he explained, and studies suggest that DNA from the tumor that circulates in the bloodstream can identify mutations present in the tumor. To test this assumption, the large international ASSESS trial compared the ability of blood testing versus standard tumor tissue testing to detect EGFR mutations.
âWe were really asking a question on behalf of patients. Is there a valid test that can identify an EGFR mutation and give me the opportunity for superior treatment, even if my lung tumor is not accessible for bronchoscopy or CT-guided biopsy? And, are the results of this blood test in agreement with the results of the âgold-standardâ tissue test?â Reck stated in a press release from the European Society of Medical Oncology.
The investigators assessed 1162 matched tumor tissue and blood samples for the presence of an EGFR mutation in lung cancer patients. An 89% agreement was found between the 2 types of tests. Plasma testing identified about half of the patients with EGFR mutations compared with tumor tissue sampling, for a sensitivity of 46%.
Reck pointed out that the tests in this study were performed in local labs used in routine clinical practice, not in a centralized lab selected for a clinical trial. This makes the results more reflective of the âclinical reality, and not a âvirtualâ trial reality,â he said.
The present study showed that the presence of EGFR mutations in circulating DNA from plasma or serum can be detected in about half of patients with the testing techniques used in this study. Commenting on the study, Rafael Rosell, MD, Catalan Institute of Oncology, Barcelona, Spain, noted that since the trial was conducted, refinements in blood tests for circulating DNA have improved the sensitivity of these tests, so in the future it should be possible to do a better job at finding EGFR and other genetic mutations.
âCell-free DNA detected in the bloodstream of cancer patients represents an excellent tool to examine genetic alterations that are usually found through tumor tissue testing. This represents one of the most astonishing phenomena in biology,â Rosell stated.
âThis work paves the way for future studies and expands the routine use of examining mutations such as EGFR mutations as part of patient care,â Rosell added.
Genetic tumor profiling, immune profiling, and immunohistocompatibility expression profiling are performed routinely at Yale Cancer Center for patients diagnosed with cancer. The results are presented to the multidisciplinary Molecular Tumor Board, which meets weekly to make treatment decisions. The following case exemplifies a personalized medicine approach and was presented by [ Read More ]
Just because whole genome sequencing can be done on a patientâs tumor doesnât mean that this will translate to a patientâs getting targeted therapy for identified genetic abnormalities, especially if that patient has pancreatic cancer. In the Individualized Molecular Pancreatic Cancer Therapy (IMPaCT) Trial, no patient with an identified genetic [ Read More ]