Transanal endoscopic microsurgery with the fluorescence lymphangiography.

[BACKGROUND] Early-stage rectal cancer can be managed with transanal endoscopic microsurgery (TEM) as a minimally invasive alternative to radical surgery. However, a major limitation of TEM is the potential for occult metastases in mesorectal lymph nodes.

[OBJECTIVE] To evaluate the feasibility and clinical utility of indocyanine green (ICG) fluorescence lymphangiography for sentinel lymph node detection during TEM.

[METHODS] A total of 95 patients with early-stage rectal cancer underwent TEM using a rigid rectoscope platform (Karl Storz TEO, Germany). Full-thickness local excision with 1-2 cm margins and primary defect closure was performed. In patients with enlarged mesorectal nodes on preoperative MRI, 5 mg of ICG was injected submucosally around the tumor, followed by laparoscopic near-infrared observation and sentinel node excision for pathological analysis.

[RESULTS] From 2009 to 2024, 95 patients (52 men, 43 women; mean age 67.4 ± 7.2 years) underwent TEM. The mean operative time was 95.5 ± 15.4 min. Postoperative complications occurred in 7 patients (7.4%), primarily bleeding and pulmonary events; no anastomotic leaks or perioperative mortality were observed. Sentinel lymph node mapping was performed in 23 patients, with occult metastases detected in 6 cases (26.1%). These patients were advised radical resection with total mesorectal excision (TME); 4 underwent TME, and 2 opted for chemotherapy. During a 12-60 month follow-up, local recurrence occurred in 3 of 56 patients with T1-T2 tumors (5.4%) and in 5 of 39 downstaged T3 patients (12.8%).

[CONCLUSIONS] TEM offers a safe, minimally invasive approach for early-stage rectal cancer. The adjunct use of ICG lymphangiography enhances detection of mesorectal lymph node metastases and helps identify patients who may require additional radical surgery with TME.