Dr. Pennell on Benefits of Liquid Biopsies in Lung Cancer

Nathan A. Pennell, MD, PhD, director, Lung Cancer Medical Oncology Program, Cleveland Clinic Taussig Cancer Institute, discusses the benefits of liquid biopsies in lung cancer.

Plasma testing for genetic variations can be helpful in scenarios where the patient does not have enough tissue for tissue testing or the wait for tissue testing results is a significant amount of time, explains Pennell. In Pennell’s practice, it is common for patients to have a tissue biopsy as well as a biopsy from somewhere else. In his practice, Pennell and his team do not have access to the tissue immediately because protocol is through the pathology department and the tissue is mailed to him, creating a wait time of weeks or a month to get results from tissue. In that setting, performing a liquid biopsy is helpful.

Plasma testing along likely cannot replace tissue testing, though its positive results are reliable, says Pennell. If a liquid biopsy shows a positive result for a mutation or gene fusion, that can be used to proceed to treatment. In common mutations like KRAS where patients likely do not have another actionable mutation, patients can proceed to systemic chemotherapy or immunotherapy. Plasma testing is going to miss about 20% of actionable mutations, which means if the plasma testing gives a negative result, the tissue test must be consulted, according to Pennell. If treatment must be started before the molecular testing results are received, Pennell suggests starting with chemotherapy alone.