An upsetting, recently published article in JAMA Oncology entitled “Patient-Paired Sample Congruence Between 2 Commercial Liquid Biopsy Tests” has cast serious doubt on the reliability of the current genetic liquid biopsy tests for men with advanced metastatic prostate cancer that we have begun to use to guide our treatment choices.
The two tests evaluated in a study, the Guardian 360 Panel and the Plasma Select Test, both claim to have very high clinical sensitivity and specificity in the identification of specific genetic markers associated with high-risk forms of prostate cancer. The research published in Jama by Drs. Torga and Pienta from the Johns Hopkins University School of Medicine showed a significant lack of agreement between these two commercial tests!
Torga and Pienta research set out to ask if either of these liquid biopsy tests was superior for men with metastatic prostate cancer. They sent split blood samples (so that each lab received a part of the same sample) from 40 men to each lab for evaluation. They found that there was almost no agreement between the two tests.
The take home is clear, neither of these tests should be relied upon when making your treatment decisions. Since the FDA has approved these tests as companion tests and both labs are certified we need to question the reliability of all the genetic-based liquid biopsy tests current deployed.
The decisions we make using these tests results are too important to allow what are flawed results to guide our treatment decisions. Liquid biopsies, despite these findings, remain a promising technology, but they are still far from being ready for prime time. Liquid biopsies are just not yet ready for clinical use.
Joel T. Nowak, MA, MSW wrote this Post. Joel is the CEO/Executive Director of Cancer ABCs. He is a Cancer Thriver diagnosed with five primary cancers - Thyroid, Metastatic Prostate, Renal, Melanoma, and the rare cancer Appendiceal cancer.