Liquid Biopsy Tests in People with Cancer: An Expert Review

March 14, 2018 7:03 pm

The following article is provided by The Clearity Foundation to support women with ovarian cancer and their families. Learn more about The Clearity Foundation and the services we provide directly to women as they make treatment decisions and navigate emotional impacts of their diagnosis.

Liquid Biopsy Tests in People with Cancer: An Expert Review

Use of tests that assess genomic variants in circulating tumor DNA (ctDNA) is on the rise. A new joint review from the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) provides an assessment of evidence on ctDNA tests in oncology. It also lays out a framework for future research and clinical practice guidelines to help better inform clinical practice.

The review, Circulating Tumor DNA Analysis in Patients With Cancer: American Society of Clinical Oncology and College of American Pathologists Joint Review, was published online today in the Journal of Clinical Oncology and the Archives of Pathology & Laboratory Medicine. It will appear in print versions of the journal following today’s online publication.

“This is an area of great interest to both pathologists and oncologists. It’s also an area where we see a lot of commercial advertisement, and a lot of enthusiasm from the public,” said Jason D. Merker, MD, PhD, FCAP, co-chair of the Expert Panel that developed the review, representing the CAP. “We thought it was a good time to look at the literature and take an evidence-based approach to various uses for ctDNA assays.”

Analysis of ctDNA allows clinicians to assess the characteristics of a patient’s tumor through a simple blood test, what is referred to as the “liquid biopsy.” The term “liquid biopsy” may refer to assays that analyze proteins, DNA, or cancer cells that circulate in the blood.  Recently, it has been used in reference to mutations found in circulating, cell-free DNA that is released by tumors, also called “circulating tumor DNA” or “ctDNA.” Compared to traditional biopsy, which involves removing a piece of tumor tissue from the body, a liquid biopsy is less invasive and is associated with less potential complications.

Despite growing excitement around the use of liquid biopsies in oncology, with possible applications ranging from cancer screening to informing treatment decisions and monitoring response to treatment, there are a number of questions with this strategy:

  • How well does the test perform? Can the test detect and measure the presence of a biomarker accurately, reproducibly, and reliably? (analytical validity). In the same vein, how should the samples for liquid biopsies be collected and handled – and how do these differ among the different types of tests? (pre-analytical considerations)
  • Do the results of the test accurately divide one population of patients into two or more separate groups? Can the test accurately detect a pathologic state or predict outcomes for groups of patients whose test results differ? (clinical validity)
  • Is it proven that using the results of the test to make clinical decisions actually benefits the patient and does not pose a risk? (clinical utility)

“Like all new things in medicine, the use of ctDNA assays in routine cancer care requires evidence of clinical utility. At present, there is insufficient evidence of clinical validity and utility for the majority of ctDNA assays in advanced cancer, including those that interrogate a panel of genes,” said Daniel F. Hayes, MD, FACP, FASCO, member of the Expert Panel that developed the review, representing ASCO.

For this review, an ASCO/CAP multidisciplinary Expert Panel examined evidence from 77 relevant articles published from January 2007 to March 2017. The review was limited to the analysis of sequence and gene copy number variants in ctDNA from solid tumors.

To read this entire article in The Clearity Portal, please click here.

Leave a Reply

Your email address will not be published.

Return to Blog Home Return to Clearity Foundation Home