["Injection of a hydrogel spacer before prostate cancer radiotherapy (RT) is known to reduce the dose to the rectal wall. Clinical results from the patient's perspective are needed to better assess a possible benefit.", 'A group of 167\xa0consecutive patients who received prostate RT during the years 2010 to 2013 with 2‑Gy fractions up to 76\xa0Gy (without hydrogel, n\xa0= 66) or 76-80\xa0Gy (with hydrogel, n\xa0= 101) were included. The numbers of interventions resulting from bowel problems during the first 2\xa0years after RT were compared. Patients were surveyed prospectively before RT, at the last day of RT, and at a median of 2\xa0and 17\xa0months after RT using a validated questionnaire (Expanded Prostate Cancer Index Composite).', 'Baseline patient characteristics were well balanced. Treatment for bowel symptoms (0 vs. 11\u2009%; p\xa0< 0.01) and endoscopic examinations (3 vs. 19\u2009%; p\xa0< 0.01) were performed less frequently with a spacer. Mean bowel function scores did not change for patients with a spacer in contrast to patients without a spacer (mean decrease of 5\xa0points) >1\xa0year after RT in comparison to baseline, with 0 vs. 12\u2009% reporting a new moderate/big problem with passing stools (p\xa0< 0.01). Statistically significant differences were found for the items "loose stools", "bloody stools", "painful bowel movements" and "frequency of bowel movements".'] Does hydrogel injection reduce rectal toxicity after radiotherapy for localized prostate cancer?