Baseline characteristics
From July 2008 to November 2016, 107 patients with acute MORC (35 patients in the SEMS group and 72 in the ES group) underwent radical resection at Zhongshan Hospital. The median patient age was 66 (range 23–94) years. As shown in Table 1, there were no major differences in baseline and oncologic characteristics, with the exception of tumour location, between the SEMS and ES groups. No stent migration or perforation was observed, although one patient experienced re-obstruction after initial successful stenting. As of the last follow-up on August 2018, the overall median follow-up duration was 35 (range 0.1–120) months. Of the 107 patients, 13 (12.1%) were lost to follow-up. However, there was no significant difference in the rate of patients lost to follow-up between the SEMS and ES groups (11.4% [4/35] vs 12.5% [9/72], respectively; P > 0.99).
Characteristics of the procedures and postoperative short-term outcomes
The characteristics of the surgical procedures and short-term postoperative outcomes of the two groups are shown in Table 2. Although open surgery was the primary approach, laparoscopic procedures were performed more frequently in the SEMS group than the ES group (11.4% vs. 0%, respectively; P = 0.010). In regard to intraoperative findings, the incidence of ascites was greater in the ES group than the SEMS group (52.8% vs. 20.0%, respectively; P = 0.001), while perforation occurred in four (5.6%) patients in the ES group. The need for intraoperative transfusion tended to be lower in the SEMS group than the ES group, but the difference was not statistically significant (2.9% vs. 13.9%, respectively; P = 0.098). In the SEMS group, jejunostomy was performed for one patient, as partial duodenectomy was required due to intraoperative findings that the tumor had invaded the duodenum.
The postoperative ICU admission rate was significantly lower in the SEMS group than the ES group (11.4% [4/35 vs. 34.7% [25/72], respectively; P = 0.011). Moreover, the complication rate was significantly lower in the SEMS group than the ES group (11.4% [4/35] vs. 29.2% [21/72], respectively; P = 0.042). The most common postoperative complications in both groups were wound infection, pulmonary infection, and anastomotic leakage, but there was no significant difference in the incidence of complications between the two groups (P > 0.05). One patient in the ES group died due to multiple organ dysfunction syndrome on postoperative day 3. Moreover, the average duration of postoperative hospitalization was significantly shorter in the SEMS group than the ES group (8.23 ± 6.50 vs. 11.18 ± 6.71 days, respectively; P = 0.033). After excluding tumors located in the cecum from the ES group, the characteristics of the surgical procedures and postoperative short-term outcomes of the two groups were compared. The results in Supplementary Table 1 show the advantages of stent placement in terms of lower ICU admission rate, reduced complication rates, and shorter postoperative hospital stays.
Long-term outcomes of all populations in the SEMS and ES groups
Kaplan–Meier curves of PFS for all patients are presented in Fig. 1A. The hazard ratio (HR) for PFS between the ES vs. SEMS groups was 1.235 (95% confidence interval [CI] 0.674–2.263; P = 0.506). The 5-year PFS rate was greater in the SEMS group than the ES group (54.0% [95% CI 34.20%–73.80%] vs. 49.1% [95% CI 35.97%–62.23%], respectively). The Kaplan–Meier curves of OS for all patients are presented in Fig. 1B. The HR for OS between the ES and SEMS group was 0.995 (95% CI 0.520–1.907; P = 0.989). The 5-year OS rate was lower in the SEMS group than the ES group (56.0% [95% CI 36.40%–75.60%] vs. 61.6% [95% CI 49.25%–73.95%], respectively).
Subgroup analyses based on tumor stage
Comparison of stage II and III disease between the SEMS and ES groups
During the follow-up period, disease progression, defined as local site recurrence and distant metastasis, was observed in 27 (29.0%) patients with stage II and III disease. There was no significant difference in the distant metastasis rate between the SEMS and ES groups (21.4% [6/28] vs. 18.5% [12/65], respectively; P = 0.740) or in the rate of local relapse (7.1% [2/28] vs. 10.8% [7/65], respectively; P = 0.719). At the time of analysis, a total of 31 (33.3%) patients died during the follow-up period. However, there was no significant difference in the mortality rate between the SEMS and ES groups (32.1% [9/28] vs. 33.8% [22/65], respectively; P = 0.873) (Table 3).
PFS curves of the 93 patients with stage II and III disease are shown in Fig. 2A. As the HR for the ES vs. SEMS groups was 1.543 (95% CI 0.774–3.075; P = 0.253), the 5-year PFS rate was 64.5% (95% CI 43.53–85.47) for the SEMS group and 52.6% (95% CI 38.64–66.52) for the ES group. The Kaplan–Meier curves of OS are presented in Fig. 2B. The HR for the ES vs. SEMS group was 1.217 (95% CI 0.559–2.646; P = 0.619), when the 5-year OS rate was 68.2% (95% CI 47.82–88.58) for the SEMS group and 64.2% (95% CI 51.46–76.94) for the ES group.
Long-term outcomes of patients with stage IV disease
Table 4 shows the clinicopathological characteristics and long-term prognostic outcome data of 14 patients with stage IV colon cancer in the two groups. The SEMS and ES groups both had seven CRC patients with synchronous liver metastases. After colectomy, the synchronous or two-stage hepatectomy rates was significantly greater in the SEMS group than the ES group (85.7% [6/7] vs. 14.3% [1/7], respectively; P = 0.029). The remaining patients received chemotherapy, transcatheter arterial chemoembolisation or other palliative treatments.
To determine the advantages of different therapeutic regimens, survival outcomes of patients who underwent colectomy only vs. colectomy combined with hepatectomy were compared. Kaplan–Meier curves of OS are shown in Fig. 3. The data showed that median OS was superior for those who underwent combined resection as compared to colectomy alone (42 vs. 6 months, respectively), and the HR for colectomy only vs combined resection was 3.258 (95% CI 0.858–12.370; P = 0.041).