Stents Plus Neoadjuvant Therapy Reshapes Outcomes in Obstructive Colorectal Cancer

When a colorectal tumor grows large enough to block the bowel, patients often face one of the most dangerous emergencies in oncology. Malignant large bowel obstruction complicates roughly 15 to 29 percent of colorectal cancer cases, and for decades the standard response was emergency surgery performed on a swollen, inflamed, poorly nourished intestine. Now a multicenter retrospective study published in BMC Cancer suggests that a more deliberate strategy, combining self-expandable metal stents with neoadjuvant therapy, may meaningfully improve both the quality of surgery and, in the modern treatment era, overall survival.

The research, led by Zhuo Han and Nan Wang of Tangdu Hospital at the Fourth Military Medical University together with colleagues from Beijing Chaoyang Hospital and Xijing Hospital, analyzed 154 patients with obstructive colorectal cancer treated between 2011 and 2025. Ninety-three patients received a self-expandable metal stent followed by neoadjuvant therapy, while 61 underwent stent placement alone before surgery. Because treatment practices evolved dramatically over the fourteen-year enrollment window, the investigators stratified their analysis into two eras, 2011 to 2020 and 2021 to 2025, to separate the effects of the combined strategy from the effects of technological progress.

The biological rationale behind the combined approach is rooted in the peculiar hostility of the obstructed bowel. Compared with non-obstructive colorectal cancer, obstructed tumors are more often left-sided, larger, more poorly differentiated, and diagnosed at more advanced stages, with a greater tendency toward peritoneal spread. Obstruction also drives a cascade of systemic problems: elevated inflammatory markers such as C-reactive protein and interleukin-6, hypoproteinemia and malnutrition, and reduced physical activity that accelerates muscle loss and frailty. Recent molecular work has even identified distinct features of the obstructed tumor microenvironment, including altered extracellular matrix stiffness, activated cancer-associated fibroblasts, and a dense infiltration of CD8-positive T cells that paradoxically correlates with worse prognosis.

Emergency surgery for these patients carries perioperative mortality rates as high as 10 to 15 percent, along with elevated risks of anastomotic leakage, wound infection, and permanent stoma formation. Self-expandable metal stents, introduced in the 1990s, offered a minimally invasive alternative: an endoscopist deploys a mesh tube across the tumor, restoring bowel continuity within hours and converting an emergency into an elective operation. Meta-analyses have shown lower early complication rates, lower mortality, and far fewer stomas with stenting compared with emergency surgery. Yet long-term oncological concerns persisted, most notably a prospective study reporting significantly higher local recurrence after stenting, possibly linked to microperforations or mechanical manipulation of the tumor releasing circulating tumor DNA.

The new study addresses those concerns by layering neoadjuvant therapy onto the stent pathway. After decompression, multidisciplinary teams at each center assessed patients for systemic treatment based on locally advanced disease, molecular subtype, resectability, and performance status. Regimens ranged from XELOX and FOLFOX chemotherapy to combinations with cetuximab for RAS and BRAF wild-type left-sided tumors, and immunotherapy for patients with microsatellite instability-high or mismatch repair-deficient tumors. The theory is that decompression first reduces bowel wall edema and peritumoral inflammation, creating a healthier substrate for treatment and surgery, while neoadjuvant drugs shrink the tumor, downstage nodal disease, and potentially eradicate micrometastases.

The short-term surgical results were striking. In the 2011 to 2020 cohort, the stent-plus-therapy group had an intraoperative stoma rate of 8.6 percent versus 29.0 percent for stent alone, and postoperative complications of 8.6 percent versus 29.0 percent, both statistically significant differences. These advantages persisted into the 2021 to 2025 period. The authors attribute this to a synergistic mechanism: stent-induced decompression resolves intestinal wall edema and restores blood supply, converting lesions once deemed unsuitable for safe anastomosis into ones where primary reconstruction is feasible, while neoadjuvant therapy further reduces tumor volume and inflammation. Avoiding a stoma carries profound quality-of-life implications, with longitudinal data showing that ostomy patients suffer persistent deficits in physical, emotional, and social functioning for up to a year after surgery.

Pathological outcomes told an equally compelling story about the modern era. In the 2021 to 2025 cohort, 20.7 percent of neoadjuvant-treated patients achieved major tumor regression, graded as Tumor Regression Grade 0 to 1, and rates of T and N downstaging reached 39.7 percent and 60.3 percent respectively, far exceeding the earlier period when regimens consisted mainly of standard chemotherapy alone. The contemporary group also showed significantly fewer positive lymph nodes and significant improvements in pathological T and N stages. The authors link this enhanced response to the evolution of neoadjuvant regimens, including targeted and immune-based combinations that act on both the primary tumor and micrometastatic disease.

Survival analysis revealed a nuanced picture. In the earlier cohort, the neoadjuvant group showed marginally better three- and five-year disease-free and overall survival, but the differences did not reach statistical significance. In the 2021 to 2025 cohort, however, the combined strategy was associated with a statistically significant improvement in overall survival, with a reported P value of 0.013, while disease-free survival had not yet diverged, possibly because follow-up in that cohort remains short at a median of 41.3 months. The authors caution that retrospective design, modest sample size, and the absence of propensity score matching limit causal inference, but the consistency of surgical and pathological benefits across both eras strengthens the overall signal.

Perhaps the most practice-changing finding concerns timing. For patients treated with a stent alone, an interval of 14 to 21 days between stenting and surgery was associated with significantly better overall survival, a window during which decompression restores nutrition, dampens systemic inflammation, and allows prehabilitation without giving the tumor unnecessary time to progress. For patients receiving neoadjuvant therapy, the calculus differs: intervals exceeding 90 days were associated with significantly worse disease-free survival, suggesting that systemic treatment should be completed and surgery performed within roughly three months. A nationwide Chinese survey cited in the paper found that nearly half of stenting hospitals operated within two weeks, while about a fifth waited ten to twelve weeks when neoadjuvant therapy was given, underscoring how variable current practice remains.

The study arrives as two prospective trials, OUTSTAND and NACSOC-02, work to confirm whether stent-based neoadjuvant strategies can be standardized for obstructive left-sided colorectal cancer, with the latter testing immunotherapy combinations after decompression. For now, the retrospective evidence offers a coherent clinical algorithm: decompress with a stent at an experienced center, use the restored physiological window to deliver modern systemic therapy tailored to molecular subtype, and schedule radical surgery within a defined interval, ideally before 90 days elapse. If prospective data validate these findings, the dreaded obstructed bowel, long a surgical emergency defined by rushed decisions and permanent stomas, may instead become the starting point of a carefully sequenced, multidisciplinary treatment plan that improves both survival and the daily lives of patients.

Subject of Research: Neoadjuvant therapy combined with self-expandable metal stent placement for obstructive colorectal cancer

Article Title: Comparative effectiveness of neoadjuvant therapy combined with stent placement versus stent alone in obstructive colorectal cancer: a multicenter retrospective analysis

Article References: Han, Z., Zhang, B., Liu, S., Wu, T., Qiao, Q., He, X., Han, J., & Wang, N. (2026). Comparative effectiveness of neoadjuvant therapy combined with stent placement versus stent alone in obstructive colorectal cancer: a multicenter retrospective analysis. BMC Cancer, 26(1), Article 1139. https://doi.org/10.1186/s12885-026-16728-2

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16728-2

Keywords: colorectal cancer, bowel obstruction, self-expandable metal stent, neoadjuvant therapy, bridge to surgery, overall survival, disease-free survival, tumor regression grade, surgical timing, stoma, immunotherapy, retrospective study