In this study, BTS using with stent in patients who presented with obstructive colorectal cancer was associated with better surgical outcomes. In a comparison of the surgery alone group and the BTS group, significant differences were found in the avoidance of emergency surgery, the presence of large wounds due to open surgery, and length of hospital stay. The median operative time was longer in the BTS group than in the surgery alone group (P < 0.001). We reasoned that the BTS group had a higher rate of laparoscopic surgery compared to the surgery alone group. The better surgical outcomes in the BTS group might lead to an improvement in the postoperative quality of life. However, in the present study, BTS using stent for obstructive colorectal cancer with curative potential was associated with impaired mid-term oncological outcomes. When the two groups were compared, no significant differences were found in relapse-free survival, overall survival, and locoregional recurrence rates, but in contrast, a significant difference was found in distant recurrence.
A meta-analysis by Ceresoli et al. in 2017 reported that stents such as BTS had no adverse effects on the 3-year or 5-year mortality rates or on local recurrence [16]. Recently, 2 meta-analyses revealed no significant difference between the stent group and the emergency surgery group in terms of overall survival, disease-free survival, and recurrence [13, 17]. In 2016, the multicenter, randomized controlled ESCO trial reported no difference in the 3-year overall survival and progression-free survival rates between the colonic stenting (BTS group) and the emergency surgery group [18].
When we designed this study, we speculated that the locoregional recurrence rate would be worse in the BTS group compared with the surgery alone group. However, in this study, the locoregional recurrence rate was not significantly different in both groups because no patients with a stent-related perforation was included in this study. If it is possible that stent-related perforations could occur in patients in the BTS group, the actual locoregional recurrence rate might be worse than that reported in this study. In 2013, the multicenter, randomized controlled Dutch Stent-In 2 trial reported that the locoregional or distant disease recurrence rate in the stent group was worse than that in the emergency surgery group and that the disease-free survival was worse in the subgroup with stent- or guidewire-related perforations [8]. The results of the present study suggested that stent placement for curable obstructive colorectal cancer might increase the rate of distant metastases even in cases without stent- related perforations. A meta-analysis by Foo et al. in 2019 reported that a BTS stent was significantly associated with a greater chance of recurrence, especially systematic recurrence, although BTS was not associated with the 3-year disease-free survival or overall survival rate [19]. In 2013, Sabbagh et al. performed a retrospective comparative study with a propensity score analysis and found a significantly poorer overall and 5-year survival rates than patients undergoing surgery only [11]. These results suggested that stents may have an adverse effect on the long-term outcomes of colorectal cancer patients [11]. That study found a higher prevalence of synchronous distant metastasis in the stent placement group (37.5%) than in the surgery-only group (10.2%) and a lower success rate (81%) in the stent group. On the contrary, the present study limited patients to those without pathological stage IV and had a high clinical success rate (97.7%) and a low stent-related perforation rate (0%).
Takahashi et al. reported that stent placement increased the plasma levels of cell-free DNA and circulating tumor DNA due to tumor manipulation [20]. Maruthachalam et al. reported that stent placement increased the cytokeratin 20 mRNA level in the peripheral blood and might be associated with increased recurrence of any type [7]. In the present study, since a significant difference was observed in the distant recurrence rate, we could not deny the possibility that tumor compression by stent placement led to molecular biological effects that were associated with distant metastases. The Dutch Stent-In 2 trial reported that the liver recurrence rate was 12.5% in the stent group, which was worse than the 6.8% in the emergency surgery group [8].
These findings should be considered in several limitations. First, this study was limited by its small sample size and its retrospective, non-randomized single-institution design. Thereby, the heterogeneity of the surgical strategy may have affected the prognostic factors. Although we limited patients to those with less than pathological stage IV cancer, the patient’s backgrounds were still heterogeneous. Second, the median follow-up time was relatively short, and a systematic difference was found in the observation period between the surgery alone group and the BTS group (median follow-up time was 49.4 and 37.8 months for the surgery alone group and BTS group, respectively). Patients in the BTS group were more recently treated than those in the surgery alone group. Given the advances in chemotherapy for recurrent colorectal cancer, there might have been a trend in the BTS group that the relapse-free survival rate was worse and the overall survival rate was better compared with the surgery alone group. Lastly, although endoscopic stent placement procedures were validated, stent devices used in this study had different lengths, types, and thickness and obtained from different vendors.