Patients with advanced NSCLC may not be healthy enough for a tissue biopsy, or might only be able to undergo limited tissue procedures, like a Fine Needle Aspirate (FNA) or Core Needle Biopsy (CNB) for diagnosis.
After first line TKI therapy, it is preferable to use a new tumour specimen for EGFR analysis though this would require another invasive tissue biopsy procedure. The key benefits of testing with plasma is that it involves a non-invasive procedure for collecting biopsy from the patient and it can be sampled as frequently as needed without putting patients at risk.
When testing plasma with the cobas® EGFR Mutation Test v2, a feature called the Semi-Quantitative Index (SQI)* is included in the report—this number is designed to reflect a trend in the EGFR mutation load. If frequently testing a patient for the EGFR mutation, tracking the SQI value and identifying a trend may lead to understanding tumour progression, an option not available in other tests.
*SQI feature is currently not available in the USA.