Utilization, Acute Complications, and Delays in Treatment Associated with Rectal Spacers for Prostate Cancer Radiotherapy.

Objective: To investigate rectal hydrogel spacer use, placement complications, and associated radiation delays in the United States.

Methods: The Merative^TM MarketScan Database was used to identify prostate cancer patients undergoing spacer placement or radiation alone between 2016 and 2021. Genitourinary and gastrointestinal complications and subsequent interventions that occurred after spacer placement but before radiation were captured. A 6-month window preceding spacer placement was employed to eliminate underlying diagnoses present before spacer placement. Delays in starting radiation after spacer placement were identified and categorized as more than one, two, or three months. A Cox proportional hazards model with a time-varying covariate of acute complications to assess the effect of complications on time-to-radiation RESULTS: We captured 3,732 spacer placements, of which 3,650 (97.8%) underwent radiation. The use of spacers among prostate cancer radiation patients increased from 0.5% in 2016 to 25.7% in 2021. Stereotactic body radiotherapy (SBRT) patients had the highest spacer use at 50.0% in 2021. Complications occurred in 6.4% (n=235) of patients before starting radiation. Of these, 5.2% (n=190) were genitourinary and 1.2% (n=43) were gastrointestinal complications. Catheterization, cystoscopy, rectal endoscopy, rectal abscess drainage were required for 21 (0.6%), 15 (0.4%), 12 (0.3%), 1 (0.03%), and 1 (0.03%) patients, respectively. Following a complication, patients had a significantly lower risk (Hazard Ratio 0.75, 95% CI 0.66 - 0.86, p<0.001) of starting radiation compared to before the complication.

Conclusions: Rectal spacer use is prevalent amongst patients undergoing SBRT. While rare, spacer placement complications occur, which can delay the start of radiation therapy.