LAUSR

Background: The analysis of circulating tumor DNA (ctDNA) is becoming an instrumental tool in the practice of precision oncology. It not only provides a non-invasive method to study the mutational composition of solid tumors, particularly when there are limitations in tissue acquisition, but also helps capturing the biological heterogeneity and genomic evolution of advanced tumors. There is tremendous variability in utilization of ctDNA among oncologists in in various solid tumors and currently there are no guidelines. Methods: We evaluated the results of all Guardant360 ctDNA tests that were requested for clinical management in advanced cancers in our academic tertiary cancer center. We identified and annotated the most common genomic alterations and variants for each disease type. Moreover, we collected variant allele frequency variants (VAF) from each report and disease. The results for each type of neoplasm were compared to the others. Results: A total of 2199 tests for 1402 patients were performed between 2015 to January 2019. The test volume increased from 162/year in 2015 to 733/year in 2018. The tests were most commonly requested in patients with the diagnosis of advanced breast adenocarcinoma (ABC)(36%), followed by non-small cell lung cancer (NSCLC)(21%), colorectal cancer (CRC)(5%). 88% of reports included at least one alteration, with a median of 3 alterations per case and median of highest VAF of 1.1%. Prostate small cell carcinoma, contained the largest number of alterations/case (median: 9.5) and highest VAF (median: 7.1%). Among common neoplasms CRC had a significantly higher VAF (Median: 5.4%), compared to NSCLC and ABC (median Citation Format: Amir Behdad, Firas Wehbe, Carmen Williams, Wenan Qiang, Athanasios Vasilopoulos, Massimo Cristofanilli MD FACP. Real-world use of circulating tumor DNA (ctDNA) in the clinical management of patients with solid tumors: A single institution’s experience [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C012. doi:10.1158/1535-7163.TARG-19-C012