Abstract 1051: Liquid biopsy in the detection of genetic biomarkers in gastrointestinal cancer

Abstract

Abstract Colorectal cancer (CRC) is one of the leading causes of morbidity and mortality worldwide. Detection prior to metastasis and appropriate therapeutic application lead to greater patient survival and quality of life. However, the diagnosis and postoperative surveillance are surrounded by limitations. Genetic biomarkers are influential factors that contribute to favorable clinical outcomes. To better understand the molecular basis associated with CRC, we investigated KRAS, NRAS, BRAF, EGFR and TP53 genes in the DNA of tumor and healthy cells using Sanger sequencing. The most frequent alteration, present only in the tumor DNA (somatic), was used to investigate, by Digital PCR (ddPCR), the detection and analysis of circulating tumor DNA (ctDNA) in the plasma. Altogether, 42 subjects made up the study, most of them male (59.5%), with a mean age of 63 years and tumors located in the right colon (21.4%). transversal (2.4%), left (4.8%), sigmoid (33.3%) and straight (38.1%). Germline and somatic allelic variants were found in the KRAS, EGFR and TP53 genes. The most frequent somatic alteration in the study was rs121913529, which showed an association with alcohol consumption (p = 0.002). Patients with a somatic mutation in TP53 are ten times more likely to die, compared with the chance of those without a mutation in this gene (OR 11.2; 95% CI 1.25 - 245). The applicability of these somatic changes in the liquid biopsy technique was demonstrated by ddPCR. Therefore, the results obtained expand the understanding of the molecular basis of CRC and present an optimization of the liquid biopsy, timely for clinical practice. Citation Format: Bianca Gomes-Fernandes, Juliana Garcia Carneiro, Rodrigo Gomes da Silva, Luiz de Marco, Luciana Bastos-Rodrigues. Liquid biopsy in the detection of genetic biomarkers in gastrointestinal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1051.