Although prostate cancer treatment is increasingly effective, its toxicities pose a major concern. The aim of our study was to assess the rate of adverse events (AEs) and the prognostic value of dose–volume histogram (DVH) parameters for the occurrence of treatment toxicity in patients treated with post-prostatectomy prostate bed radiotherapy (RT). The AEs were scored according to the CTCAE v.5.0. The rectum and bladder were contoured according to the RTOG Guidelines. The DVH parameters were assessed using data exported from the ECLIPSE treatment-planning system. Genitourinary (GU) and gastrointestinal (GI) toxicity were analysed using consecutive dose thresholds for the percentage of an organ at risk (OAR) receiving a given dose and the QUANTEC dose constraints. A total of 213 patients were included in the final analysis. Acute grade 2 or higher (≥G2) GU AEs occurred in 18.7% and late in 21.3% of patients. Acute ≥G2 GI toxicity occurred in 11.7% and late ≥G2 in 11.2% of the patients. Five patients experienced grade 4 AEs. The most common adverse effects were diarrhoea, proctitis, cystitis, and dysuria. The most significant predictors of acute ≥G2 GI toxicity were rectum V47 and V46 (p< 0.001 andp< 0.001) and rectum wall V46 (p= 0.001), whereas the most significant predictors of late ≥G2 GI AEs were rectum wall V47 and V48 (p= 0.019 andp= 0.021). None of the bladder or bladder wall parameters was significantly associated with the risk of acute toxicity. The minimum doses to bladder wall (p= 0.004) and bladder (p= 0.005) were the most significant predictors of late ≥G2 GU toxicity. Postoperative radiotherapy is associated with a clinically relevant risk of AEs, which is associated with DVH parameters, and remains even in patients who fulfil commonly accepted dose constraints. Considering the lack of survival benefit of postoperative adjuvant RT, our results support delaying treatment through an early salvage approach to avoid or defer toxicity.
尽管前列腺癌治疗日益有效，但其毒性反应仍构成主要关注点。本研究旨在评估前列腺切除术后前列腺床放疗患者的不良事件发生率，并探讨剂量-体积直方图参数对治疗毒性发生的预后价值。不良事件依据CTCAE v.5.0标准进行分级评估。直肠与膀胱勾画遵循RTOG指南规范。剂量-体积直方图参数通过ECLIPSE治疗计划系统导出数据进行分析。采用连续剂量阈值法，结合危及器官特定剂量受照体积百分比及QUANTEC剂量限制标准，对泌尿生殖系统与胃肠道毒性进行系统评估。 最终纳入分析的213例患者中，急性≥2级泌尿生殖系统不良事件发生率为18.7%，晚期发生率为21.3%；急性≥2级胃肠道毒性发生率为11.7%，晚期发生率为11.2%。5例患者出现4级不良事件。最常见不良反应包括腹泻、直肠炎、膀胱炎及排尿困难。急性≥2级胃肠道毒性的最显著预测因子为直肠V47与V46（p<0.001；p<0.001）及直肠壁V46（p=0.001），而晚期≥2级胃肠道不良事件的最显著预测因子为直肠壁V47与V48（p=0.019；p=0.021）。膀胱及膀胱壁参数均未显示与急性毒性风险显著相关。膀胱壁最小剂量（p=0.004）与膀胱最小剂量（p=0.005）是晚期≥2级泌尿生殖系统毒性的最显著预测因子。 术后放疗存在具有临床意义的不良事件风险，该风险与剂量-体积直方图参数相关，即使在满足常规剂量限制标准的患者中依然存在。鉴于术后辅助放疗缺乏生存获益证据，本研究结果支持通过早期挽救治疗策略延迟放疗时机，以规避或延缓毒性反应发生。
肿瘤(癌症)患者之家