T1 CRC and ESD(GIE, Jan-2026)

### T1 Colorectal Cancer (CRC)

• **T1 CRC** refers to early-stage colorectal cancer where the tumor has invaded the submucosa but has not yet spread further.
• It is subdivided into **superficial submucosal invasive cancer (s-SMIC)** and **deep submucosal invasive cancer (d-SMIC)** based on the depth of invasion.
• **s-SMIC**: Less invasive; better prognosis.
• **d-SMIC**: More invasive; higher risk of lymphovascular invasion and metastasis.

### Endoscopic Submucosal Dissection (ESD)

• **ESD** is a minimally invasive endoscopic technique used to remove early-stage gastrointestinal tumors, including T1 CRC, en bloc (in one piece) to achieve clear margins.
• It is increasingly being used as an alternative to primary surgery for patients with suspected T1 CRC, especially for those with s-SMIC.

### Key Findings from the Study (2011–2022)

1. **Effectiveness of ESD**:

• ESD was more effective in achieving a free vertical margin (VM-R0) in suspected s-SMIC cases compared to d-SMIC cases.
• The VM-R0 rate for suspected s-SMIC was 90.6%, while it was significantly lower for suspected d-SMIC at 55.4%.
• The en bloc resection rate was also higher in s-SMIC (90.5%) compared to d-SMIC (61.9%).

2. **Challenges in d-SMIC**:

• For suspected d-SMIC cases, the VM-R0 rate particularly decreased for pT1Sm2-3 lesions (55.7%).
• None of the investigated clinical or polyp-related features (age, sex, polyp location, size, morphology, and Hiroshima classification) could predict VM-R1 resections in d-SMIC cases.

3. **Adverse Events**:

• The adverse event rate was slightly higher in d-SMIC cases (5.8%) compared to s-SMIC cases (3.6%).

4. **Implications for Treatment**:

• The lower success rate of ESD (in terms of VM-R0) for d-SMIC highlights the need for careful patient selection.
• For suspected d-SMIC cases, alternative treatment strategies, including surgery, may be more appropriate to ensure complete resection and reduce the risk of recurrence.

### Clinical Significance

• For **s-SMIC**, ESD is a highly effective and safe option, offering high rates of curative resection with minimal complications.
• For **d-SMIC**, the lower VM-R0 rates suggest that ESD alone may not always be sufficient, and primary surgery may be considered for better oncological outcomes.

### Future Perspectives (2026 and Beyond)

• As ESD techniques continue to evolve, future studies may focus on improving the success rates for d-SMIC cases.
• The development of advanced imaging techniques and predictive tools could help in better identifying patients who are suitable for ESD versus surgery.
• Long-term follow-up data from ongoing or future studies (such as the one in 2026) will be crucial in determining the role of ESD in managing T1 CRC, particularly for d-SMIC cases.