Abstract 391: Utility of circulating tumor cell (CTC) in advanced gastric cancer

Abstract

Abstract Circulating tumor cells (CTCs), known as the “leukemic phase” of solid tumor, have been associated with poor prognosis and clinical outcome in various cancer including breast and colorectal. However, fewer studies reported characteristic and usefulness of CTC as an indicator in gastric cancer (GC). In this study, we evaluated utility of CTC in advanced GC cancer. First, we confirmed detection rate of GC cancer cell lines as a spiking test, and then defined CTC as DAPI+, EpCAM+ and CD45- cells through immunofluorescence stating. To determine a cut-off for CTC of GC, we assessed the number of CTCs in blood of 22 healthy volunteers, and observed 1 (3/22) to 2 (1/22) of CTCs. Based on these results, we determined CTC positivity of GC as more than 3 CTCs. When we evaluated CTC positive rate in Stage IV GC patients, 28 patients were CTC positive (30.1%) with the median number of CTC 5 (range 3 to over 100). Interestingly, 3 out of 28 patients were showed more than 100 CTCs. While, in operable GC patients (Stage I to III), CTC positivity was 18.4% (7/38) and median number of CTC was 4 (range 3 to 9) in CTC positive patients. These results showed that Stage IV GC patients have high number of CTCs than operable GC patients. Tumor histology and Lauren classification did not affect to CTC positivity in Stage IV and operable GC patients. We also observed the potential use of CTC in serial follow-ups and one of the cases shows the decreasing CTCs followed by clinical response. In conclusion, this study demonstrates that detection of CTC may be useful prognostic indicator of GC cancer patients. Citation Format: Won Suk Lee, Jeong Min Kim, Woo Sun Kwon, So Jung Lim, Tae Soo Kim, Ga Yun Kim, Sung Ho Choi, Byung Hee Jeon, Min Kyu Jung, Joong Bae Ahn, Hyun Cheol Chung, Sun Young Rha. Utility of circulating tumor cell (CTC) in advanced gastric cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 391. doi:10.1158/1538-7445.AM2015-391