High dose-rate Intra-Operative Radiation Therapy During High Risk Genitourinary Surgery: Initial Observations and a Proposal for its Study in Bladder Cancer.

Background: High dose-rate Intra-Operative Radiation Therapy (HD-IORT) is used to provide effective local control for patients with high-risk locally advanced or recurrent tumors. However, the utility of HD-IORT for patients with bladder cancer has not been studied.

Objective: To characterize our institutional experience with HD-IORT in patients with cancer requiring genitourinary surgery, in an effort to identify patients with bladder cancer that may benefit from HD-IORT.

Methods: We performed a retrospective review of all patients who have undergone HD-IORT during genitourinary surgery at our institution. Patients were stratified by surgical margin status, and primary outcomes assessed were overall survival, recurrence free survival and 90-day complications. Patients undergoing cystectomy and HD-IORT with sarcomatoid urothelial cancer were compared to a similar cohort undergoing cystectomy alone. A sample case of one such patient is discussed in detail.

Results: 84 patients at our institution have undergone HD-IORT with genitourinary surgery. Positive surgical margin status was the greatest predictor of both OS (HR = 3.42) and RFS (HR = 2.61). The overall 90-day complication rate was 61%, with wound infections (43%) and GI complications (21%) being most common. 4 of these patients had sarcomatoid urothelial histology, and all are still alive with >2 yrs follow up. This compares to a 52% 1 yr survival in our sarcomatoid urothelial cohort (25 pts) that did not undergo HD-IORT.

Conclusions: Our institutional experience with HD-IORT has been promising, particularly among patients with locally advanced disease and sarcomatoid histology. We are currently enrolling patients in a multi-institutional registry to assess the utility of HD-IORT in high risk bladder cancer.