Transanal endoscopic microsurgery after radiation or chemoradiation therapy for rectal cancer — peculiarities and results

INTRODUCTION: the standard treatment for patients with locally advanced rectal cancer is the use of chemoradio-therapy (CRT) or intensive radiation therapy (RT) regimens with delayed surgery. Moreover, in 10–25% of cases, patients experience complete disappearance of the tumor during treatment. Current approaches to the management of cases with a good response involve organ-sparing treatment in patients with a complete clinical response (cCR), which means dynamic observation of the patient, or local excision of the scar at the site of a pre-existing tumor in cases of a near complete clinical response (nCR). AIM: to analyze the results of treatment of patients with rectal cancer who had a good response to RT/CRT and who underwent transanal endoscopic microsurgery (TEM). PATIENTS AND METHODS: from 2019 to 2023, 20 patients with rectal adenocarcinoma underwent TEM after RT/CRT. In all patients, the tumors were located in the distal rectum, which required either abdominoperineal resection or ultra low ante-rior rectal resection. The median interval between RT and surgery was 22 (12–78) weeks. In 5 (25.0%) patients included in the study, a cCR was registered for neoadjuvant treatment. In 15 cases, TEM was performed in patients with nCR. RESULTS: operation time was 117 minutes, the blood loss was 40 ml. A complicated postoperative period was observed in 4 (20.0%) patients, among whom the most serious complication was suture failure of the sutured intestinal defect — in 3 (15.0%) patients. Unfavorable prognosis factors were identified in 7 (35%) patients, while final TEM was performed in only 2 (28.6%) of them. In other clinical situations, active follow-up of patients was performed — local tumor recurrence was not detected in any case. With a median follow-up of 31.5 (3-54) months, signs of distant metastases were recorded in 2 (10.0%) cases. Local relapse at 12.3 months was detected in one case (5.0%). The cumulative three-year local recurrence rate was 6.2 ± 6.1%. Overall and disease-free three-year survival rates were 83.3 ± 10.8% and 80.4 ± 10.4%, respectively, and stoma-free survival was 92.9 ± 6.9%. CONCLUSION: despite the fact that TEM in patients with rectal cancer after RT is an effective and safe method of treatment, its use in patients with cCR to confirm a complete response is inappropriate and carries an unnecessary risk of postoperative complications and possible functional dysfunction. The main indication for the use of TEM after RT/CRT is nCR, when local excision of the scar at the site of a pre-existing tumor allows not only to determine their pathological nature and treatment approach, but also for most patients it is a radical surgical intervention with a relatively low risk of local relapse. © 2024, Association of Coloproctologists of Russia. All rights reserved.