Baseline characteristics
From March 2018 to January 2021, 36 patients were enrolled. A flowchart of these patients is shown in Fig. 1A. After exclusion of patients with palliative operation (n = 3) and patient occurred myocardial infarction (n = 1), a total of 32 patients were included in the subsequent analysis Fig. 1B. Stent insertion was performed in 24 patients, 3 of which underwent emergent surgery owing to stent placement failure and then transferred to ES group. Emergency surgery was performed in 12 patients in all while one patient was excluded owing to occurred myocardial infarction on the first postoperative day. In SEMS group, 15 patients underwent radical surgery 7 days (5–8 days) after stents placement, 6 patients underwent palliative surgery. CTC detection were performed before operative procedures and after 7 days of operative procedures which include stents placement, ES operation and operation after stents placement.
In SEMS group (Table 1), the average age was 71.24(8.9) year [mean, (SD), years]. Obstructive CRC were located in the transverse colon (left-side) in 2 patients, descending colon in 4 patients, and sigmoid colon in 15 patients. Among them, 9 patients were diagnosed as cTNM stage II and 12 patients were diagnosed as cTNM stage III.
Postoperative clinical data (Table 2) include surgical approach, the permanent stoma rate, adjuvant therapy and postoperative TNM stage. 7 of 11 patients suffered permanent stoma in ES group while 3 of 15 patients suffered in SEMS group who underwent radical surgery (p = 0.043). 13 of 15 patients in SEMS group underwent laparoscopic resection compared 2 of 11 patients in ES group (p = 0.001). 7 of 11 patients received adjuvant therapy while 14 patients in SEMS (p = 0.128). Other postoperative characteristics, including pT stage (p = 0.999), pN stage (p = 0.398) and pM stage (p = 0.999).
Technical success of SEMS placements. 24 patients underwent SEMS insertion, however, the guide wire failed to pass through the stenosis and obstruction in 3 patients. All of 3 patients transferred to ES group and performed conventional emergency surgery to decompress.
Clinical success of relieving obstruction and complications. Among the 21 patients in SEMS group, 1 patient suffered perforation 8 days after SEMS placements and underwent surgery promptly. In ES group, 12 patients underwent emergency surgery successfully, only one patient occurred myocardial infarction on the first postoperative day and died on the fifth day (excluded case).
Detection of CTCs. The number of CTCs detected within the peripheral blood circulation before/after SEMS placement and operation or ES in 7 days. As shown in Fig. 2A and B, there were no statistically significant differences before and after stent placement (34.90 vs 38.33, p = 0.90), neither between the SEMS group and ES group in the first CTC levels (34.90 vs 58.09, p = 0.394). We further compared the second CTC in SEMS group and first CTC in ES group, no significant differences (38.33 vs 58.09, p = 0.632) were observed (Fig. 2C). In order to analysis whether ES or operation after stent placement would have effects on the number of CTCs, we compared the third CTC in SEMS and the second CTC in ES, however, no major differences (24.17 vs 42.27, p = 0.225) were observed in two group (Fig. 2D).