Bladder stone formation around polyethylene glycol after use of SpaceOAR Hydrogel

Radiation therapy is used as primary, adjuvant, and salvage therapy for prostate cancer. When using radiation therapy, the SpaceOAR^® system is considered easy to use and useful for reducing the irradiated dose and toxicity to the rectum. Although SpaceOAR^® system have been reported some adverse event including death.

A 74-year-old male was diagnosed with prostate cancer of clinical stage cT2aN0M0 and intermediate risk by the National Comprehensive Cancer Network guidelines. We inserted the SpaceOAR^® Hydrogel before performing intensity-modulated radiation therapy, as the patient had ulcerative colitis. We did not recognize any complications during or after the procedure, although magnetic resonance imaging revealed hydrogel in the bladder retrospectively. Fourteen months after the procedure, the patient was presented with macrohematuria and we found a bladder stone including hydrogel.

We report the first case of a bladder stone after use of SpaceOAR^® Hydrogel. We must be careful of taking place it.