Rectal complications following SpaceOAR insertion after prior pelvic radiation

Treating prostate cancer with radiation therapy in patients with a history of prior pelvic radiation may be limited by rectal dose constraints and the risk of rectal toxicity. Rectal spacers have been shown to improve rectal dosimetry in the treatment of prostate cancer. This study aimed to evaluate the safety and outcomes of hydrogel spacer placement, specifically SpaceOAR, between the rectum and prostate in prostate cancer patients who had previously undergone radiation therapy. In this retrospective case series, we analysed the medical records of 8 sequential patients undergoing reirradiation in the setting or prior pelvic radiation, who had received transperineal SpaceOAR placement. We documented the incidence of complications after SpaceOAR placement, before and after undergoing radiation therapy. There was a spectrum of complications in this patient cohort, ranging from pelvic pain to more severe complications such as rectal perforation abscess and fistula. Severe complications occurred in 2 of the 8 patients. Re-irradiation may increase the risk of normal tissue complications; however, hydrogel spacer placement using SpaceOAR in prostate cancer patients with prior pelvic radiation was associated with a higher rate of rectal complications than expected in a small series of patients. We urge caution when using SpaceOAR in this patient group.