Oncologic safety of colonic stenting as a bridge to surgery in leftsided malignant colonic obstruction:Current evidence and prospects

Approximately 7%-29%of patients with colorectal cancer present with colonic obstruction.The concept of self-expandable metal stent(SEMS)insertion as a bridge to surgery(BTS)is appealing.However,concerns on colonic stenting possibly impairing oncologic outcomes have been raised.This study aimed to review current evidence on the short-and long-term oncologic outcomes of SEMS insertion as BTS for left-sided malignant colonic obstruction.For short-term outcomes,colonic stenting facilitates a laparoscopic approach,increases the likelihood of primary anastomosis without a stoma,and may decrease postoperative morbidity.However,SEMS-related perforation also increases local recurrence and impairs overall survival.Moreover,colonic stenting may cause negative oncologic outcomes even without perforation.SEMS can induce shear forces on the tumor,leading to increased circulating cancer cells and aggressive pathological characteristics,including perineural and lymphovascular invasion.The conflicting evidence has led to discordant guidelines.Well-designed collaborative studies that integrate both oncologic outcomes and data on basic research(e.g.,alteration of circulating tumors)are needed to clarify the actual benefit of colonic stenting as BTS.

Oncologic impact of colonic stents for obstructive left-sided colon cancer

Colonic stenting has had a significant positive impact on the management of obstructive left-sided colon cancer(OLCC) in terms of both palliative treatment and bridge-to-surgery(BTS). Notably, many studies have convincingly demonstrated the effectiveness of stenting as a BTS, resulting in improvements in shortterm outcomes and quality of life, safety, and efficacy in subsequent curative surgery, and increased cost-effectiveness, whereas the safety of chemotherapy after stenting and the long-term outcomes of stenting as a BTS are controversial. Several studies have suggested an increased risk of perforation in patients receiving bevacizumab chemotherapy after colonic stenting. In addition, several pathological analyses have suggested a negative oncological impact of colonic stenting. In contrast, many recent studies have demonstrated that colonic stenting for OLCC does not negatively impact the safety of chemotherapy or long-term oncological outcomes. The updated version of the European Society of Gastrointestinal Endoscopy guidelines released in 2020 included colonic stenting as a BTS for OLCC as a recommended treatment. It should be noted that the experience of endoscopists is involved in determining technical and clinical success rates and possibly oncological outcomes. This review discusses the positive and negative impacts of colonic stenting on OLCC treatment, particularly in terms of oncology.

Self-expanding metal stent placement and pathological alterations among obstructive colorectal cancer cases

BACKGROUND Experimental studies suggest that self-expanding metal stents(SEMSs)enhance the aggressive behavior of obstructive colorectal cancer.The influence of SEMS placement on pathological alterations remains to be elucidated.AIM To determine whether SEMS placement is associated with molecular or pathological features of colorectal carcinoma tissues.METHODS Using a nonbiased molecular pathological epidemiology database of patients with obstructive colorectal cancers,we examined the association of SEMS placement with molecular or pathological features,including tumor size,histological type,American Joint Committee on Cancer(AJCC)-pTNM stage,and mutation statuses in colorectal cancer tissues compared with the use of transanal tubes.A multivariable logistic regression model was used to adjust for potential confounders.RESULTS SEMS placement was significantly associated with venous invasion(P<0.01),but not with the other features examined,including tumor size,disease stage,mutation status,and lymphatic invasion.In both the univariable and multivariable models with adjustment for potential factors including tumor location,histological type,and AJCC-pT stage,SEMS placement was significantly associated with severe venous invasion(P<0.01).For the outcome category of severe venous invasion,the multivariable odds ratio for SEMS placement relative to transanal tube placement was 19.4(95%confidence interval:5.24–96.2).No significant differences of disease-free survival and overall survival were observed between SEMS and transanal tube groups.CONCLUSION SEMS placement might be associated with severe venous invasion in colorectal cancer tissue,providing an impetus for further investigations on the pathological alterations by SEMSs in colorectal cancer development.