Abstract 1585: Evaluation of Circulating Free DNA in Non-Metastatic Breast Cancer

Abstract Background Circulating free DNA (cfDNA) is becoming an important tool in diagnosis and prognosis in several types of cancer. In this study we evaluated the association between cfDNA concentrations in peripheral blood with tumoral features of non-metastatic breast cancer patients. Methods cfDNA was extracted from plasma of peripheral blood of patients with non-metastatic breast cancer and healthy controls. In patients, blood samples were collected before and after surgery, while in controls samples were collected after their results of breast cancer screening. Detection of copy number of PUM1 and RNaseP genes were performed in a QuantStudio® 3D Digital PCR System and quantification was obtained with QuantStudio® 3D AnalysisSuite™ Cloud Software. Raw values were compared among the different clinicopathologic features. Results In total 26 patients and 25 controls were included. There were significant differences between controls and patients for levels counts of PUM1 and RNaseP genes (p<0.0001 in both cases). In patients, median concentrations before and after surgery for PUM1 were 10.6 copies/uL (range: 2.2-16.3) vs. 7.6 copies/uL (range: 1.3-12.8), respectively (P=0.04) and for RNaseP were 6.6 copies/uL (range: 0.9-20.0) vs. 5.3 copies/uL (range: 0.5-16.0), respectively (P=0.103). Hormonal tumors produced more cfDNA in terms of RNaseP at diagnosis (7.9 vs. 5.6, P=0.049). When we compared patients according to their hormonal status with controls, RNaseP was able to identified positive hormonal receptors patients (P<0.0001). There were no significant differences between other clinicopathologic features. There was a significant decrease after surgery of RNaseP levels in node negative tumors (P=0.049) and PUM1 levels in >10mm tumors (P=0.041). Conclusions Our results suggest that PUM1 is a better diagnostic biomarker for non-metastatic breast cancer because RNaseP loss sensitivity in negative hormone receptor cases. Hormonal tumors produced more circulating free DNA. RNaseP could be used to monitor node negative patients and PUM1 to patients with >10mm tumors. Citation Format: Jhajaira M. Araujo, Jaime Ponce, Alexis Murillo, Pamela Rebaza, Pierina Danos, Alfredo Aguilar, Ricardo Fujita, Henry L. Gomez, Joseph A. Pinto, Jose Buleje. Evaluation of circulating free DNA in non-metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1585.