Background
Despite advances in radiotherapy planning, some long-term prostate cancer survivors experience persistent symptoms. Although overall quality of life appears comparable between patients treated with definitive and salvage radiotherapy and aligns with normative data, prostate-specific deficits—particularly bowel symptoms—may persist.
Methods
This study assessed prostate-specific quality of life using the EORTC QLQ-PR25 questionnaire in 141 patients with localized or locally advanced prostate cancer (T1–4 N0 M0) treated with external radiotherapy between 2011 and 2021. After a median follow-up of 63.6 months, bowel symptom scores and radiation doses to the anal canal and rectum were analyzed in 71 patients who received definitive radiotherapy (median dose: 78 Gy) and 70 who received salvage radiotherapy (median dose: 70 Gy). Bowel symptom scores were correlated with previously reported global health status scores (EORTC QLQ-C30) from the same cohort and compared to those of a reference population.
Results
Tumor stage distribution (localized vs. locally advanced) was similar between groups. Patients in the definitive group were older at the time of survey than those in the salvage group (79 years vs. 75 years; p = 0.009). Mean doses to the anal canal and rectum were comparable between groups, reflecting consistent application of dose constraints across treatment intents. EORTC QLQ-PR25 scores, including bowel symptom scores, did not differ significantly between the groups. Patients reporting bowel symptoms (n = 92) received significantly higher mean doses to the anal canal (41.0 Gy vs. 35.1 Gy; p < 0.001), whereas rectal doses were similar. Mean anal canal dose (Dmean) correlated with bowel symptom scores (r = 0.307; p < 0.001), whereas no correlation was observed for mean rectal doses. A Dmean threshold of 32 Gy to the anal canal differentiated patients with and without bowel symptoms. Higher bowel symptom scores were associated with lower global health status (r = −0.469; p < 0.001). Compared to the reference population, patients showed significantly and clinically relevant higher bowel symptom scores, indicating a greater symptom burden.
Conclusions
Bowel symptoms are a significant concern after radiotherapy for prostate cancer and are associated with reduced quality of life. Since higher anal canal doses correlate with increased symptom burden, greater efforts to spare this structure during treatment are warranted.
Trial Registration

This study was retrospectively registered.