EP698 - The CivaSheet: A Flexible Approach to Intraoperative Radiation Therapy

Purpose/Background: Total neoadjuvant therapy (TNT) has become a mainstay for rectal cancer treatment prior to surgical intervention or surveillance, also known as "watch and wait". For those patients who subsequently develop local recurrence following either approach, further treatment with external beam radiation to the pelvis is limited by prior exposure during TNT. It is therefore reasonable to offer these patients intraoperative radiation therapy as an adjunct when considering re-operative surgery. Our project aims to highlight our center's experience with a novel intraoperative radiation therapy modality: the CivaSheet.

Methods/Interventions: We performed a retrospective analysis and review of all patients at our institution, a tertiary referral center in the Southeastern US, who had undergone CivaSheet placement between 2017-2025. All patients who underwent surgery with simultaneous placement of intraoperative brachytherapy sheet (CivaSheet) were included. We obtained baseline demographic data including patient age, BMI, gender, and race. Initial presenting symptoms, prior treatment and surgery, and outcomes from pre- and post-intraoperative radiation treatments were obtained from the electronic health record. Descriptive statistics were used to report the results of the data.

Results/Outcomes: A total of 12 patients underwent CivaSheet placement at our center from 2017-2025. The mean age at the time of surgery was 50.2 years (32-72 years). 10 patients identified as male (83.3%) and 7 (58.3%) identified as white. The most common presenting symptom that led to a rectal cancer diagnosis was rectal bleeding (4, 33.3%), followed by large bowel obstruction (2, 16.6%). More than half (7, 58.3%) had previously undergone surgery, with 6 (85.7%) of those patients having undergone low anterior resection (LAR) or abdominoperineal resection (APR). The most common indication for CivaSheet placement was preoperative concern for R1-R2 resection, as determined from preoperative imaging (CT, MRI) (6, 50%). Other indications were palliative (bleeding or pain) or curative, which included high risk of local recurrence and locally advanced rectal cancer. The majority of our patients underwent a pelvic exenteration (10, 83.3%) compared to LAR. These were primarily performed open (9, 75%). The average length of stay following surgery was 16.83 days (6-34 days). The most common postoperative complications were further surgical or procedural intervention (6, 50%), including percutaneous nephrostomy tube or image-guided drainage. Additionally, 5 (41.5%) developed postoperative ileus and 4 (33.3%) developed a clinically relevant bowel obstruction. There were no complications directly related to the CivaSheet.

Conclusion/Discussion: Our center's experience with the application of the CivaSheet as a form of intraoperative radiation therapy shows promise regarding ease of use, accessibility, and patient tolerance. We hope that our use of the palladium core-lined applicators will open the door to larger sample, multi-center investigation into the use of CivaSheets as a feasible, effective, and potentially financially superior modality for the administration of intraoperative radiation therapy.

Figure 1. CivaSheet placement and fixation within the pelvis following pelvic exenteration
Figure 1. CivaSheet placement and fixation within the pelvis following pelvic exenteration
Table 1. Patient and cancer characteristics of those who underwent CivaSheet placement 2017-2025.
Table 1. Patient and cancer characteristics of those who underwent CivaSheet placement 2017-2025.