STER (Submucosal Tunneling Endoscopic Resection)

Some tumors in the digestive tract don't grow on the inner surface where standard endoscopy or EMR/ESD can easily reach — they grow deeper, within the muscle layer of the esophagus or stomach wall itself. STER (Submucosal Tunneling Endoscopic Resection) was developed specifically to reach and remove these tumors: rather than cutting directly into the tumor from the surface, the endoscopist creates a tunnel within the wall of the digestive tract, reaches the tumor from within that tunnel, removes it, and then closes the entry point — leaving the surface lining largely intact and avoiding any external incision entirely.

Yes, very much so — this is one of the more consistently well-performing techniques in advanced endoscopy. Technical success — successfully reaching and removing the tumor — is reported above 90% across published studies, and complete removal of the whole tumor in one piece is achieved in the large majority of cases. Recurrence after successful removal is uncommon. Complications are relatively infrequent and generally manageable when they occur. A genuinely reassuring local point: published research on this exact technique has come directly from a Hyderabad-based research team, reflecting real, established regional expertise rather than an unfamiliar or experimental approach. The section further down this page, ‘The evidence in more detail,’ has the specific study data.

• Leiomyomas — the most common tumor type treated with this technique
• Gastrointestinal stromal tumors (GISTs)
• Other tumors growing within the muscle layer of the esophagus, stomach, or gastroesophageal junction that are symptomatic, growing, or of uncertain nature on imaging

• Before: endoscopic ultrasound and sometimes biopsy to characterize the tumor and confirm STER is the right approach
• During: performed under general anesthesia; a tunnel is created within the esophageal or stomach wall, the tumor is carefully dissected free and removed through the tunnel, and the entry point is closed with clips
• After: a period of monitoring and a gradual return to normal diet; most patients recover quickly given the minimally invasive nature of the technique
• Follow-up: pathology review of the removed tumor, with surveillance based on the specific findings

This section is for anyone who wants the specific research behind the summary above — it's not necessary reading to understand the basics of this procedure, but it's here for transparency.

An Indian study from a Hyderabad-based research team evaluating STER in upper GI subepithelial tumors reported technical success in 97.7% of cases and complete single-piece (en bloc) removal in 88.4%, with no major adverse events and no tumor recurrence at a mean follow-up of over 12 months. A large systematic review and meta-analysis covering more than 2,900 patients found similarly strong outcomes across international data. A US multicenter study reported en bloc resection and retrieval in 94.1% of lesions, while a separate large Chinese series using a refined marking technique reported complete resection in 100% of cases, en bloc resection in 98.3%, and a low adverse event rate of 4.5% with no severe complications and no residual tumor detected on follow-up.

STER removes subepithelial tumours through a submucosal tunnel, leaving the overlying mucosa intact to close the defect. It is performed in the Advanced Endoscopy Clinic by our gastroenterologists who also perform POEM, since the tunnelling technique is the same. To have an EUS report on a subepithelial lesion reviewed, book a consultation.