Use of Intraoperative Radiation Therapy in Rectal Cancer

A 65-year-old man presented with abdominal pain. Imaging demonstrated a large bowel obstruction and further workup revealed locally advanced upper-third rectal cancer. He underwent a diverting loop colostomy and total neoadjuvant therapy (TNT) with 5-fluorouracil, leucovorin, and oxaliplatin and chemoradiotherapy. At the completion of his neoadjuvant treatment, his tumor was downstaged from a T4bN2M0 to T4bN0M0 (Fig. 1; pre- and posttreatment MRI). His posttreatment imaging showed an incomplete response to treatment with concern for the involvement of the left pelvic sidewall. After a multidisciplinary discussion, the plan was to proceed with surgery with intraoperative radiation therapy (IORT) of the pelvic sidewall given a concern for a possible positivemargin.Heunderwentroboticpelvicexenteration,ileal conduit creation, and IORT to the left pelvic sidewall. His final pathology showed staging of T4bN0 with negative margins. Postoperatively, his course was complicated by prolonged ileus, pseudoaneurysm, active bleeding of the left internal iliac artery 1 week postoperatively requiring coil embolization, and pelvic abscess formation treated with CT-guided drainage. He eventually recovered and was discharged to a long-term acute care facility 2 months after the operation. © The ASCRS 2024.