SpaceOAR Hydrogel spacer injection prior to stereotactic body radiation therapy for men with localized prostate cancer

By: Payne HA, Pinkawa M, Peedell C, et al.

A growing consensus suggests that stereotactic body radiation therapy (SBRT) is similarly as effective as conventionally fractionated radiotherapy. The SpaceOAR hydrogel rectal spacer placed between the prostate and rectum reduces radiation-induced rectal injury in patients receiving conventionally fractionated radiotherapy, but spacer efficacy with SBRT is unclear.

Systematic searches of Medline, Embase, and the Cochrane Center Register of Controlled Trials for studies in men who received the SpaceOAR hydrogel spacer prior to SBRT (>5.0 Gy fractions) for localized prostate cancer were performed.

In 11 studies with 780 patients, SBRT protocols ranged from 7 to 10 Gy per fraction with total dose ranging from 19 to 45 Gy. Perirectal distance achieved with the rectal spacer ranged from 9.6 to 14.5 mm (median 10.8 mm). Compared to controls receiving no spacer, SpaceOAR placement reduced the radiation delivered to the rectum by 29% to 56% across a dosimetric profile curve.

Early follow-up found grade 2 GI complications were reported in 7.0% of patients and no early grade 3+ GI complications were reported. Over 16 months median follow-up, freedom from biochemical failure ranged from 96.4% to 100%.