Abstract 4583: Combined analysis of circulating tumor cells, fecal occult blood test and serum carcinoembryonic antigen for early detection and monitoring recurrence of patients with colorectal cancer

Current methods for clinical early detection and disease monitoring of patients with colorectal cancer (CRC) are immunochemical fecal occult blood test (iFOBT) and serum levels of carcinoembryonic antigen (CEA), which are known with low sensitivity. There is an unmet need to seek for additional molecular tools for early detection and disease monitoring of patients with CRC. Whether enumeration of circulating tumor cells (CTCs) supplements current clinical tests and facilitates early detection and monitoring disease progression was investigated. A total of 109 pre-operative patients with CRC (including early and advanced stages) and 65 non-cancerous controls were enrolled in this study. CTCs were enriched from the peripheral blood of these individuals by using the PowerMag negative selection system. Immunofluorescence staining of epithelial cell adhesion molecule (EpCAM), and podoplanin (PDPN, a marker related to poor cancer progression) was performed to define the two distinct subtypes of CTCs. Heterogeneous CTCs expressing PDPN or EpCAM are defined in the peripheral blood of patients with CRC. Regardless clinical stages in patients, the number of both EpCAM+-CTCs and PDPN+-CTCs explicitly differentiated non-cancerous controls and patients with CRC, and were also correlated with clinicopathological diagnosis. Receiver operating characteristic analysis demonstrated that the sensitivity and specificity of EpCAM+-CTCs was 86.32% and 78.46%, respectively, when the cutoff value was 23 EpCAM+-CTCs/mL. Using 7 PDPN+-CTCs/mL as the cutoff value, the sensitivity and specificity of PDPN+-CTCs was 77.98% and 75.38%, respectively. 84.2% and 80.3% of patients with serum CEA < 5 ng/mL were found to have higher EpCAM+-CTCs and PDPN+-CTCs counts, respectively. In addition, simultaneous measurements of iFOBT and CTCs could compromise the false-positive rate of iFOBT, while measurements of CEA and CTCs are applicable to monitor cancer recurrence after surgery. This study implicates that CTC testing supplements the current clinical methods to facilitate early detection and disease monitoring in CRC. Citation Format: Wei-Shan Hung, Wen-Sy Tsai, Tzu-Min Wang, Hsueh-Ling Hsu, Hsuan Liu, Chia-Yu Yang, Ching-Ping Tseng, Ju-Chien Cheng. Combined analysis of circulating tumor cells, fecal occult blood test and serum carcinoembryonic antigen for early detection and monitoring recurrence of patients with colorectal 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 4583.