Turnaround Time of Plasma Next-Generation Sequencing in Thoracic Oncology Patients: A Quality Improvement Analysis

Genomic analysis of plasma cell-free DNA has become a widespread tool for advanced non-small-cell lung cancer care. Whereas accuracy has been reported on widely, its usefulness is also tied tightly to its turnaround time (TAT), which is not well studied.

We studied the TAT of commercial plasma next-generation sequencing (NGS; Guardant360) for 533 results from 461 patients at our center between August 2016 and October 2019. The study received institutional review board approval as a quality improvement study; therefore, the results of the test and clinical setting were not analyzed.

TAT from blood draw to result (median of 9 days) was slightly longer than the TAT from laboratory receipt to result, a median of 7 days. Testing volume at our center increased three-fold over the time of the study. During this period, clinical TAT decreased from an initial median of 12 days to a median of 8 days in 2018, but more recently the median increased slightly to 9 days. During the most recent 12 months, 231 (95%) of 247 cases resulted within 14 days from blood draw, with delayed results usually because of billing, whereas 44 cases (18%) resulted within 7 days of blood draw. Studying 92 cases drawn in the most recent 3-month period, the median time of result receipt was 4:01 pm Eastern Time/1:01 pm Pacific Time; 39 results (43%) were returned after 5:00 pm Eastern Time.

In a large single-institution experience, we find that plasma NGS results can routinely be expected within 2 weeks, but uncommonly result within 1 week, supporting the need for new strategies to incorporate plasma NGS into the initial genotyping of advanced non-small-cell lung cancer.