Rectal Perforation Associated with Magnetic Resonance-Guided Radiation Therapy (MRgRT) after Peri-SpaceOAR Abscess Formation: A Case Report.

Abstract

Background In definitive radiation therapy for prostate cancer, SpaceOAR, a hydrogel spacer, is widely used to decrease irradiated dose and toxicity of rectum. On the other hand, periprostatic abscess formation is known as a rare adverse effect of SpaceOAR. There is a lack of reports clarifying the association between aggravation of abscesses and radiation therapy, and whether SpaceOAR insertion succeeded or not. Case presentation We report a case of a 78-year-old high-risk prostate cancer patient. After SpaceOAR insertion into the correct space, he started to receive external beam radiation therapy (EBRT). He developed a fever, perineal pain and frequent urination after the completion of EBRT, and the magnetic resonance imaging (MRI) revealed a peri-SpaceOAR abscess. Scheduled brachytherapy was postponed, administration of antibiotics and opioid via intravenous drip was commenced, and transperineal drainage was performed. After the alleviation of the abscess, additional EBRT instead of brachytherapy was performed with MRI-guided radiation therapy (MRgRT). On the last day of the MRgRT, perineal pain reoccurred, and MRI and colonoscopy detected the rectal perforation. He received an intravenous antibiotics drip and hyperbaric oxygen therapy (HBOT), and fully recovered from the rectal perforation. Conclusions Our report indicates that EBRT can lead to severe rectum complication by causing inflammation for patients with a peri-SpaceOAR abscess. Furthermore, HBOT was effective for the peri-SpaceOAR abscess and rectal perforation associated with EBRT.