Dr. Marshall on Genetic Testing in Gastrointestinal Cancer

John L. Marshall, MD, chief, Hematology and Oncology, professor, medicine and oncology, director, Otto J. Ruesch Center for the Cure of Gastrointestinal Cancers, Lombardi Comprehensive Cancer Center, Georgetown University, discusses the evolution of genetic testing in gastrointestinal cancer.

Although genetic testing can identify individual gene mutations, science and technology have evolved to include next-generation sequencing, which uses a large piece of tissue to look for more genes at one time, Marshall says. A more advanced form of testing that warrants further understanding is proteome analysis, which requires a larger, higher-quality tissue sample, Marshall explains.

When considering liquid biopsy, blood testing that is not tissue enriched can be effective, but not in all patients, Marshall notes. For those patients whose mutations do not appear in their blood alone, tissue-enriched blood testing allows for a deeper exploration of potential mutations based on sequencing from a tumor, Marshall says. Like other forms of genetic testing, liquid biopsy is evolving, and both types of blood tests have distinct clinical roles, Marshall concludes.