A systematic review and meta-analysis of acupuncture versus sham/placebo acupuncture for postoperative gastrointestinal dysfunction in cancer patients: Evidence from randomized controlled trials

This systematic review and meta-analysis represents an important milestone in oncology acupuncture research, being the first study to specifically compare true acupuncture versus placebo acupuncture for postoperative gastrointestinal dysfunction in cancer patients. The investigators analyzed 11 randomized controlled trials involving 1,923 patients, providing robust evidence on the specific efficacy of acupuncture beyond placebo effect. Postoperative gastrointestinal dysfunction is a common and problematic complication in oncology patients undergoing surgery, characterized by interrupted intestinal motility that prevents effective bowel transit and food tolerance. This condition manifests as nausea, vomiting, abdominal distension, and delayed passage of gas and bowel movements, and may progress to bowel obstruction.

In addition to significant discomfort, gastrointestinal dysfunction prolongs hospital stay, increases medical costs, and may raise postoperative morbidity and mortality. The methodology employed followed rigorous scientific standards, with a comprehensive search of eight databases through August 2024. Inclusion criteria were specific: adult cancer patients who developed gastrointestinal dysfunction after surgery, comparing different acupuncture modalities (electroacupuncture and transcutaneous electrical acupoint stimulation) against sham/placebo controls. The most commonly used acupuncture points were ST-36, ST-37, ST-25, PC-6, SP-6, and LI-4, mainly from the Stomach and Spleen meridians, applied during the perioperative period in 20-30 minute sessions.

Results demonstrated statistically significant superiority of true acupuncture across all primary outcomes. Time to first flatus was reduced by an average of 11.57 hours, time to first bowel movement by 14.06 hours, time to recovery of bowel sounds by 9.79 hours, and length of hospital stay by 1.22 days. Subgroup analysis revealed that transcutaneous electrical acupoint stimulation showed benefits across all evaluated parameters, while electroacupuncture demonstrated efficacy for time to flatus and bowel movement but not for length of stay, suggesting a possible placebo effect for this last parameter. From a mechanistic standpoint, acupuncture may improve gastrointestinal function through multiple pathways: vagal nerve activation via the dorsal motor nucleus, modulation of the JAK2/STAT3 signaling pathway mediated by α7nAChR in macrophages, suppression of pro-inflammatory cytokine expression, and restoration of gastrointestinal motility.

Experimental studies show that electroacupuncture modulates jejunal function mainly through parasympathetic pathway activation, with Aδ and C fibers serving as fundamental neural mediators. Additionally, acupuncture may modulate the gut microbiota and increase butyric acid production, promoting bowel motility. In terms of safety, only one study reported treatment-related adverse events, including hematoma, acute pain, and residual needling sensation after needle removal. These events were considered mild and transient, with no reports of serious adverse events in any of the included studies.

The study has important limitations to consider when interpreting results. Substantial heterogeneity observed in analyses may be attributed to variations in acupuncture modalities, cancer types, sample sizes, and sham/placebo acupuncture protocols. All included studies were conducted in Chinese populations, limiting generalizability to other ethnic groups. Quality of evidence was rated as low mainly due to risk of bias and unexplained inconsistencies across studies.