Editorial Comment on Ischemic proctitis after low-dose-rate brachytherapy using hydrogel spacer for prostate cancer.

An absorbable hydrogel spacer (SpaceOAR System; Augmenx, Waltham, MA, USA) has been available in Japan since 2018. The number of patients who received radiation therapy using hydrogel spacer for prostate cancer has been increasing. The wide‐spread use of this hydrogel spacer must be expected to reduce rectal dose and rectal morbidity. Meanwhile, some adverse events using hydrogel spacer have been reported. Iinuma et al. reported a case of rectal penetration by hydrogel spacer. Imai et al. reported a case of rectal ulcer associated with hydrogel spacer. Also, Toriumi et al. reported a case of ischemic colitis by hydrogel spacer in this case report. Fortunately, each case showed a spontaneous healing under conservative therapy. Gathering and analyzing information concerning clinical experiences of hydrogel spacer can make a suitable indication and contra‐indication criteria. Also, this effort must be necessary to achieve a safety use of hydrogel spacer and avoid severe adverse events in future.

Conflict of interest

Nobumichi Tanaka is affiliated with an endowed chair funded by Nihon Medi‐Physics Co.