Actionable insights: Liquid NGS in community oncology practice.

Abstract

e15081 Background: Liquid-based next-generation sequencing (NGS) is an integral test alongside tissue biopsy for identifying actionable mutations in various cancers. Currently, most practicing oncologists order liquid NGS when tissue biopsy is not feasible or concurrently with tissue biopsy to guide management with targeted therapies. However, concurrent testing can increase healthcare costs. We aim to explore whether liquid NGS has the same clinical utility as tissue biopsy in certain malignancies in a community-based oncology practice. Methods: A retrospective analysis was conducted at a community-based practice in Wichita, Kansas from 2022-2024. Data was collected through chart review and entered into a REDCap database. Adult patients with solid tumors who underwent Guardant360 liquid biopsy were included in the study. The primary objective was to compare and evaluate efficacy and assess concordance of genetic alterations identified by liquid NGS and tissue NGS. Descriptive statistics were used for data summarization. Results: The study analyzed 168 adult patients (90 males, 78 females). The cohort consisted of Caucasians (85.3%), African Americans (7.7%), Hispanics (3.2%), and Asians (3.8%). Twenty-two cancer subtypes were represented, including prostate (29.9%), lung (27.5%), breast (12%), colon (9.6%), and other malignancies (21%). The most common histologic type was adenocarcinoma (74.4%), with the majority of patients having metastatic disease. Comparing liquid NGS (n = 168) to tissue NGS (n = 89), liquid NGS demonstrated a shorter median turnaround time (8 vs. 13 days) and identified more genes overall (27 vs. 18 actionable, and 572 vs. 153 other variants). The average number of genes identified per patient was higher with liquid NGS (8.76 vs. 1.66). In 13 cases with repeated liquid biopsies, 3 patients had new actionable mutations identified. In subgroup analysis, liquid-based NGS outperformed tissue NGS in detecting actionable mutations, particularly in prostate (70% vs. 16%) and lung cancers (64.4% vs. 31.1%). Concordance rates between liquid and tissue NGS were 40% for lung and 33% for prostate cancer. Conclusions: Liquid-based NGS can be a reliable and effective tool for identifying targetable mutations. In our dataset, for specific cancer subtypes like prostate and lung cancer, it can be used as a first-line test for finding actionable mutations without the need for tissue NGS, potentially reducing the overall financial burden in oncology care.