e15167 Background: Trans-anal full-thickness local excision (LE) for patients with moderately advanced rectal cancer (MARC) whose tumors respond well to neoadjuvant therapy, is one approach for organ preservation. Some authors call for abandoning this procedure because it causes frequent and severe complications. We aim to report our post-operative complications rate and severity following this procedure. Methods: This is a retrospective review of the complications observed in 10 patients who underwent LE at our center between May 2017-January 2019. Primary outcomes were the presence and nature of complications associated with the treatment course. Results: Five patients were treated according to Phase II trial and received three months of FOLFOX chemotherapy followed by concurrent chemo-RT. Five additional patients received only concurrent chemo-radiotherapy as they were treated off protocol. Radiation therapy (RT) dose ranged between 45-54 Gy and the interval between completion of RT and LE ranged between 6-15 weeks; median 11.5 weeks. Gross residual disease was resected with no margin in nine patients. The size of removed specimens ranged between 6.8-1.4cm; median 2.2 cm with a depth of resection of 1.5-0.4 cm; median .6 cm. Two patients had a very low residual gross abnormality and the surgical resection extended to the dentate line. Both patients experienced grade III complications of severe pain, infection and fistula formation. Of the remaining 8 patients with tumors located between 3-8 cm from the anal verge, two patients developed grade II complications requiring a short course of antibiotics and symptomatic treatment. In both cases, symptoms resolved within one week. Conclusions: Post-operative complications in this setting are not prohibitive if LE doesn’t extend to the dentate line and the resection is limited to only residual abnormality with no mucosal margin. A complete pathological response, confirmed by LE after neoadjuvant therapy provides valuable prognostic information and can influence the intensity and burden of future follow up. The risk of surgical complications is acceptable in view of these advantages. LE remains a viable option in pursuing organ preservation for MARC when complete remission is achieved by neoadjuvant therapy.
PO-0795: Preoperative radiotherapy and local excision of rectal cancer: Results of a prospective study