Organ preservation and local excision for rectal cancer: Long-term oncologic outcomes.

3655 Background: Organ preservation is a desired outcome for rectal cancer patients after neoadjuvant chemoradiotherapy. In patients where a complete response is in question, endoscopically assisted full-thickness local excision offers a great option. Long-term data with this approach is limited. We report our experience with transanal endoscopic microsurgery (TEM) status post chemotherapy. Methods: Between January 2005 and October 2019, from a prospectively maintained rectal cancer database, we identified all patients who underwent TEM for adenocarcinoma after neoadjuvant CRT. Demographic data as well as follow-up interval and oncologic outcomes were reviewed and analyzed. Results: Ninety-two patients who underwent TEM for rectal cancer were included. The mean age was 67 years (32–94), 66% were male, and the mean BMI was 29.3 kg/m² (19.1–43). ASA classifications were II in 38%, III in 51%, and IV in 5% of patients. The mean tumor size was 3.1 cm (1–6) and mean estimated blood loss (EBL) was 29 mL (0–500). Postoperative 30-day morbidity occurred in 6.5% of patients, with no mortalities. The mean follow-up was 57.5 months (0.4-194.5), during which 7.6% of patients developed local recurrence and 6.5% developed systemic metastases. Based on final pathology, 48 patients with a complete pathologic response (ypT0) had local recurrence and distant metastasis rates of 4% and 2%, respectively. In patients with stage I disease (n=35), local recurrence occurred in 11% and distant metastasis occurred in 9%. Stage II patients (n=7) experienced a 14% rate of local recurrence with no distant metastases. Among stage III patients (n=2), both local and distant failure occurred in 50% of cases. Conclusions: TEM after neoadjuvant CRT was associated with excellent oncologic outcomes in patients achieving complete pathologic response. Selected patients with favorable residual disease experienced acceptable recurrence rates, supporting TEM as a potential organ-preserving strategy in this subgroup. In contrast, higher pathologic stage was associated with substantially increased local and distant failure, highlighting the need for strict selection, pathology-driven decision-making, and close surveillance.