ER-STER for cervical esophageal submucosal tumors via PEG

ER-STER (Endoscopic Retrograde Submucosal Tunnel Resection) represents an innovative approach to address the challenges of resecting cervical esophageal submucosal tumors (SMTs), which are difficult to access and treat using conventional endoscopic techniques due to the limited maneuvering space and proximity to the upper esophageal sphincter (UES). This method utilizes a retrograde approach via a percutaneous endoscopic gastrostomy (PEG) to overcome these limitations.

### Key Features of ER-STER:

1. **Concept and Purpose**:

• ER-STER proposes accessing cervical esophageal SMTs retrogradely through a PEG tract, rather than the conventional oral route.
• This approach aims to enlarge the working space and reduce manipulation near the sensitive UES region, minimizing discomfort for the patient.

2. **Procedure Overview**:

• A submucosal tunnel is created from the anal side of the esophagus (via the PEG tract) to the tumor site. This tunnel allows en bloc resection of the SMTs in the cervical esophagus.
• The retrograde access improves visualization and maneuverability, which are often compromised in oral-side tunneling due to space constraints.

3. **Steps Involved**:

The ER-STER procedure consists of six key stages:

• **Preoperative Evaluation**: Imaging and planning to determine tumor location and feasibility of PEG placement.
• **PEG Creation**: A PEG is inserted in the left upper quadrant under imaging guidance, avoiding major vessels and the gastric antrum.
• **Scope Insertion**: A gastroscope (slim or therapeutic) is introduced retrogradely through the PEG tract.
• **Lesion Localization**: The tumor is identified using pre-marked clips or tattooing for orientation.
• **Retrograde Tunnel Resection**: Submucosal injection creates a stable tunnel from the anal side, enabling precise tumor removal.
• **Closure of Access Sites**: Both the PEG site and the submucosal tunnel are closed to prevent complications.

4. **Technical Considerations**:

• **Submucosal Injection**: Performed 3–5 cm beyond the lesion on the anal side to ensure a stable tunnel.
• **Orientation Control**: Clips or tattooing placed orally before the procedure prevent disorientation during retrograde tunneling.
• **Insufflation Management**: Low-pressure carbon dioxide insufflation minimizes leakage and ensures safe lumen distension.
• **Navigating Tight Spaces**: Techniques like gentle torque control, patient head elevation, and using slimmer scopes help overcome the narrow thoracic inlet.

5. **Advantages**:

• Enlarged working space and improved visualization compared to oral-side STER.
• Reduced manipulation near the UES, which decreases patient discomfort.
• Preservation of overlying mucosa, minimizing the risk of postoperative strictures.
• Better orientation during tumor resection, enhancing procedural accuracy.

6. **Safety Measures**:

• Peri-procedural antibiotics to prevent stoma infection or mediastinal contamination.
• Careful handling of the PEG tract and use of CO₂ insufflation to reduce perforation and leakage risks.
• Expert endoscopic technique to avoid retrograde perforation.

7. **Potential Risks**:

• PEG-related complications such as stoma infection, retrograde perforation, or mediastinal contamination.
• Stricture formation, though less likely due to mucosal preservation.
• Theoretical risks of procedural failure due to anatomical or technical challenges.

### Current Status and Future Directions:

• **Validation Phases**:
• ER-STER is still a theoretical concept and has not yet undergone preclinical or clinical testing.
• Structured feasibility studies, including cadaveric testing, animal studies, and pilot human trials, are needed to assess its safety and efficacy.
• Evaluation metrics will focus on en bloc resection rate, perforation risk, infection incidence, stricture formation, and procedural time.

• **Limitations**:
• The technique lacks preclinical or clinical data to confirm its effectiveness and safety.
• Requires specialized training and expertise in retrograde tunneling and PEG-related procedures.

• **Future Potential**:
• ER-STER holds promise as a novel solution for difficult-to-access cervical esophageal SMTs.
• If validated through rigorous studies, it could become a standard approach for these challenging cases, offering significant advantages over conventional methods.

In summary, ER-STER via PEG introduces a groundbreaking retrograde technique for cervical esophageal SMTs, addressing the limitations of conventional oral-side endoscopic resection methods. While promising, it remains theoretical and warrants thorough preclinical and clinical validation to establish its feasibility and safety.