LAUSR

It has been reported that the examination of circulating tumor cells (CTCs) is beneficial for predicting tumor stage or treatment response. The epitherial cell adhesion molecule (EpCAM) and cytokeratin has been used as epithelial markers for the identification of CTCs. Since the epithelial-mesenchymal transition is one of malignant phenotype of cancer cells, it is necessary to investigate other markers which might detect mesenchymal CTCs. This study aims to clarify the clinical significance of EpCAM negative and CEA positive CTCs in patients with gastric cancer. Forty patients who underwent operation for gastric cancer were enrolled in this study. A total of 10ml peripheral blood samples were obtained preoperatively. Informed consent to participate in this study was obtained from all of the patients before their surgery. This study was approved by the Human Ethics Review Committee of our University. After collection of mononuclear cell fraction, these cells were stained by PAPI, anti-CD45, anti-EpCAM, anti-cytokeratin, and anti-CEA (CD66e) antibody. We enumerated the number of cells which showed EpCAM, cytokeratin, and CEA positive expression among CD45 negative cells. ROC analyses were performed for investigating predictive value of these cell counts for distant metastasis. We examined association between these cell counts and clinicopathological features. ROC analyses revealed that the AUC for predicting distant metastasis using EpCAM, Cytokeratin, and CEA positive cell counts were 0.583, 0.638, and 0.769, respectively. The median number of EpCAM negative and CEA positive cells was 231 (range: 0-61897). The cell counts of EpCAM negative and CEA positive cells were significantly associated with Tumor depth (p=0.0084), lymph node metastasis (p=0.0107), and tumor size (p=0.023). CEA might be useful marker for detecting high risk of recurrence in patients with gastric cancer. Citation Format: Yuichiro Miki, Masakazu Yashiro, Tomohisa Okuno, Kishu Kitayama, Tatsuro Tamura, Takahiro Toyokawa, Hiroaki Tanaka, Kazuya Muguruma, Kosei Hirakawa, Masaichi Ohira. Clinical significance of EpCAM-negative and CEA-positive circulating tumor cells in gastric carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3791. doi:10.1158/1538-7445.AM2017-3791