Abstract 2108: Comparative analysis of fusion gene detection rates in tissue versus blood samples from Chinese diverse solid tumors

Abstract Background: The landscape of genetic alterations, particularly fusion genes, plays a critical role in the diagnosis and treatment of various solid tumors. As liquid biopsy methods evolve, understanding the differences in mutation frequencies between tissue and blood samples becomes essential for precision oncology. This study aimed to evaluate the detection rates of specific fusion genes in both tumor tissue and blood samples from patients with diverse solid tumors using a 733-gene panel through Next-Generation Sequencing (NGS). Methods: We conducted a comprehensive analysis of 23 types of solid tumors (including bladder cancer (BLCA), breast cancer (BRCA), biliary tract cancer (BTC), cervical cancer (CESC), colorectal cancer (COAD), esophageal cancer (ESCA), gastrointestinal stromal tumors (GIST), head and neck squamous cell carcinoma (HNSC), intestine cancer, kidney renal clear cell carcinoma (KIRC), liver hepatocellular carcinoma (LIHC), melanoma, neuroendocrine tumors, non-small cell lung cancer (NSCLC), ovarian cancer (OV), pancreatic adenocarcinoma (PAAD), prostate cancer (PRAD), sarcoma (SARC), small cell lung cancer (SCLC), stomach cancer (STAD), thyroid carcinoma (THCA), thymoma (THYM), and uterine corpus endometrial carcinoma (UCEC)). The frequencies of fusion genes (including ALK, BRAF, ESR1, FGFR1, FGFR2, FGFR3, MET, NRG1, NTRK1, NTRK2, NTRK3, PDGFB, PDGFRA, RET, ROS1) were calculated from NGS results of tissue and blood samples. Results: Significant differences in fusion gene detection rates were observed between tissue and blood samples for several cancers. ALK fusions were significantly more prevalent in tissue samples from NSCLC (2.4% vs 0.9%, P<0.05), COAD (0.1% vs 0.5%, P<0.05), and THCA (1.6% vs 9.8%, P=0.04). BRCA fusions showed similar trends in NSCLC (0.1% vs 0.3%, P<0.05), HNSC (0.1% vs 1.5%, P=0.03), STAD (0.1% vs 0.4%, P=0.01), and COAD (0.1% vs 0.7%, P<0.05). Furthermore, FGFR2 fusions were detected significantly more in blood than tissue in STAD (0.5% vs 1.1%, P=0.03). Other fusion genes did not exhibit significant differences in detection rates between the two sample types. Notably, in blood tests, ALK (9.8% in THCA and 5.0% in THYM), BRAF (2.3% in melanoma), NTRK1 (2.4% in THCA), and NTRK3 (2.1% in intestine) had detection rates exceeding 2%. In tissue specimens, ALK (2.4% in NSCLC), FGFR2 (2.0% in BTC), and RET (3.1% in THCA) were the only fusion genes with detection rates over 2%. Conclusion: This study highlights significant discrepancies in the detection rates of fusion genes between tissue and blood samples across various solid tumors, emphasizing the potential of blood-based biomarkers in clinical practice. These findings suggest the need for integrated approaches in managing and monitoring the genetic landscape of solid tumors, enhancing personalized treatment strategies. Citation Format: Jun-Ling Wang, Hong-Wei Li, Hong-Xia Liu, Xiu-Ping Li, Jian-Peng Hu, Qian Xiong, Jin-Si Yang, Zong-Sheng Wu, Ting Ji. Comparative analysis of fusion gene detection rates in tissue versus blood samples from Chinese diverse solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2108.