Abstract 4175: Endoscopic stent insertion for obstructive colorectal cancer may induce tumor cell dissemination into the peripheral circulation, resulting in viable circulating tumor cell detection
Authors: Yamashita Shinya , Tanemura Masahiro , Shimizu Yosuke , Kuwai Toshio , Urata Yasuo , Taniyama Kiyomi 
Published: August 2018

Abstract
The placement of a self-expanding metallic stent (SEMS) in obstructive colorectal cancer (OCRC) is acknowledged to be a safe and effective procedure for the relief of obstruction. However, there is concern that shear forces acting on the tumor during stent expansion may release cancer cells into the circulation, resulting in distant metastasis. The aim of the present study was to determine whether colonic stent insertion increases viable circulating tumor cells (v-CTCs) in the peripheral blood. For detecting v-CTCs of colorectal cancer (CRC), we employed a novel method, TelomeScan F35 detection system. The system was constructed with a GFP-expressing attenuated adenovirus, in which the telomerase promoter regulates viral replication to detect only viable cancer cells. 7.5 ml of peripheral blood samples were obtained before/after stent insertion and after operation. GFP-positive and CD45-negative cells were counted as v- CTCs. This study was a single institution trial, approved by the Kure Medical Center IRB (No. 25-40). Between October 2013 and June 2015, 8 patients, aged 62-85 years (5 males and 3 females) were enrolled. Median follow-up was 28.1 months (range 15.5-34.6 months). All patients underwent successful SEMS insertion. Five patients had an Eastern Cooperative Oncology Group performance status of 0, and the remaining 3 patients had performance status of 1 or 2 (PS1 1, PS2 2). OCRCs were located in the sigmoid colon in 5 patients, descending colon in 2 patients, and transverse colon in 1 patient. Four patients were diagnosed as TNM stage II, and 4 patients were diagnosed as stage III. Stent insertion was performed as a bride to surgery in 7 patients and for palliation in one patient. Surgical resection (R0) was performed in 7 patients. No patients required a permanent stoma and have any complications. Four patients had no v-CTCs before SEMS placement, two of four measurable patients had an increased number of v-CTCs after SEMS placement (1-3 v-CTCs), and one of two patients with increased v-CTCs developed distant lymphatic metastasis 24 months after surgery despite curative resection and receiving systemic chemotherapy with UFT+LV. Four patients had v-CTCs (1-19 cells) before SEMS placement, and two of these four patients had an increase in the number of v-CTCs (20-21 cells) after SEMS placement, while one of the four patients died early with distant metastasis. In conclusion, the present study demonstrated that endoscopic stent insertion may result in tumor cell dissemination into the peripheral circulation and may induce early distant metastasis. Although stenting has some advantages as a BTS in OCRC, the oncological risk and long-term prognosis of this approach have not been clarified. The conclusions of this study may open a window of opportunity for raising an alarm about SEMS placement in OCRC.
Citation Format: Shinya Yamashita, Masahiro Tanemura, Yosuke Shimizu, Toshio Kuwai, Yasuo Urata, Kiyomi Taniyama. Endoscopic stent insertion for obstructive colorectal cancer may induce tumor cell dissemination into the peripheral circulation, resulting in viable circulating tumor cell detection [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 4175.