講演情報
[SY8-7]Clinical Role of PAEM/ EID for pT1b Lower Rectal Cancer
*Yu Maruyama1, Keigo Sato1, Moe Aung Paing1, Nozomi Furuichi1, Keiichi Oshima1, Yuki Itoi1, Hirohito Tanaka1, Hiroko Hosaka1, Shiko Kuribayashi1, Toshio Uraoka1 (1. Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Japan)
Background & Aims: Total mesorectal excision (TME)-based radical resection is standard for cT1b or deeper lower rectal (Rb) cancer, but it may compromise anal function and require a stoma. With an aging population and increasing demand for function preservation, local resection has gained attention. Surgical approaches such as MITAS are applied up to cT1b despite oncological limitations, whereas conventional endoscopic resection is not indicated due to difficulty in securing a negative vertical margin. Per-anal endoscopic myectomy and endoscopic intermuscular dissection (PAEM/EID) has recently emerged as a novel endoscopic approach. We evaluated the clinical outcomes of PAEM/EID for cT1b Rb.
Methods: PAEM/EID are indicated for cT1b Rb cancer patients with high surgical risks or who refuse surgery, and for lesions with severe fibrosis where securing vertical margins via ESD is difficult. We retrospectively analyzed seven pT1b Rb cancer cases treated with PAEM/EID from Sept 2024 to Oct 2025.
Results: The median age was 76 years (range, 47-83) and the median tumor size was 25mm (range, 15-105). En bloc resection was achieved in all cases. Endoscopic closure of the muscle defect was complete in 2, incomplete in 2, not performed in 3. One delayed bleeding occurred and was successfully managed endoscopically. Pathology revealed lymphatic invasion in 3, venous invasion in 4. All achieved pHM0 and pVM0. Additional surgery was performed in 2 cases. Despite short follow-up, no recurrence occurred in 5 cases without additional surgery.
Discussion: PAEM/EID provides an en bloc specimen that enables precise assessment of pathological risk for lymph node metastasis, which is essential for individualized decision-making. However, the optimal surveillance strategy after R0 resection of pT1b cancer, particularly in patients who do not undergo additional surgery despite risk factors, remains unclear.
Conclusion: In our series, PAEM/EID demonstrated favorable short- and middle-term outcomes and may serve as a selective organ-preserving strategy for cT1b lower rectal cancer.
Methods: PAEM/EID are indicated for cT1b Rb cancer patients with high surgical risks or who refuse surgery, and for lesions with severe fibrosis where securing vertical margins via ESD is difficult. We retrospectively analyzed seven pT1b Rb cancer cases treated with PAEM/EID from Sept 2024 to Oct 2025.
Results: The median age was 76 years (range, 47-83) and the median tumor size was 25mm (range, 15-105). En bloc resection was achieved in all cases. Endoscopic closure of the muscle defect was complete in 2, incomplete in 2, not performed in 3. One delayed bleeding occurred and was successfully managed endoscopically. Pathology revealed lymphatic invasion in 3, venous invasion in 4. All achieved pHM0 and pVM0. Additional surgery was performed in 2 cases. Despite short follow-up, no recurrence occurred in 5 cases without additional surgery.
Discussion: PAEM/EID provides an en bloc specimen that enables precise assessment of pathological risk for lymph node metastasis, which is essential for individualized decision-making. However, the optimal surveillance strategy after R0 resection of pT1b cancer, particularly in patients who do not undergo additional surgery despite risk factors, remains unclear.
Conclusion: In our series, PAEM/EID demonstrated favorable short- and middle-term outcomes and may serve as a selective organ-preserving strategy for cT1b lower rectal cancer.