Tanaka Tomoki, Yorozu Atsunori, Sutani Shinya, Yagi Yasuto, Nishiyama Toru, Shiraishi Yutaka, Ohashi Toshio, Hanada Takashi, Saito Shiro, Toya Kazuhito, Shigematsu Naoyuki
Department of Radiology, Tokyo Medical Center, National Hospital Organization, Meguro-ku, Tokyo, Japan; Department of Radiology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
Department of Radiology, Tokyo Medical Center, National Hospital Organization, Meguro-ku, Tokyo, Japan.
Brachytherapy. 2018 Sep-Oct;17(5):799-807. doi: 10.1016/j.brachy.2018.05.008. Epub 2018 Jun 21.
We analyzed factors associated with rectal toxicity after iodine-125 prostate brachytherapy (BT) with or without external beam radiation therapy (EBRT).
In total, 2216 prostate cancer patients underwent iodine-125 BT with or without EBRT between 2003 and 2013. The median followup was 6.9 years. Cox proportional hazards modeling was used for univariate and multivariate analyses to assess clinical and dosimetric factors associated with rectal toxicity. Dosimetric parameters from 1 day after implantation (Day 1) and 1 month after implantation (Day 30) were included in the analyses.
The 7-year cumulative incidence of Grade 2 or higher rectal toxicity was 5.7% in all patients. The multivariate analysis revealed that antiplatelet or anticoagulant therapy, neoadjuvant androgen deprivation therapy, treatment modality, Day 1 rectal volume receiving 100% of the prescribed dose (RV), and the Day 30 minimal percent of the prescribed dose delivered to 30% of the rectum (RD) were associated with rectal toxicity. Day 1 RV was a common predictor in both BT-alone and the BT + EBRT groups. The 5-year cumulative incidence of Grade 2 or higher rectal toxicity was 12.6%, 5.9%, and 1.7% for BT + 3-dimensional conformal radiation therapy, BT + intensity-modulated radiation therapy, and the BT-alone groups, respectively (p < 0.001).
Rectal dosimetric parameters in BT were associated with late rectal toxicity. Although the risk of rectal toxicity was higher when EBRT was combined with BT, with proper and achievable rectal dose constraints intensity-modulated radiation therapy yielded less toxicity than 3-dimensional conformal radiation therapy.
我们分析了在接受或未接受外照射放疗（EBRT）的碘-125前列腺近距离放疗（BT）后与直肠毒性相关的因素。
2003年至2013年间，共有2216例前列腺癌患者接受了碘-125 BT，部分患者同时接受或未接受EBRT。中位随访时间为6.9年。采用Cox比例风险模型进行单因素和多因素分析，以评估与直肠毒性相关的临床和剂量学因素。分析纳入了植入后1天（第1天）和植入后1个月（第30天）的剂量学参数。
所有患者中2级或更高等级直肠毒性的7年累积发生率为5.7%。多因素分析显示，抗血小板或抗凝治疗、新辅助雄激素剥夺治疗、治疗方式、接受100%处方剂量的第1天直肠体积（RV）以及第30天直肠30%体积接受的最小处方剂量百分比（RD）与直肠毒性相关。第1天RV是单纯BT组和BT + EBRT组的共同预测指标。对于BT + 三维适形放疗、BT + 调强放疗和单纯BT组，2级或更高等级直肠毒性的5年累积发生率分别为12.6%、5.9%和1.7%（p < 0.001）。
BT中的直肠剂量学参数与晚期直肠毒性相关。虽然EBRT与BT联合使用时直肠毒性风险更高，但通过适当且可实现的直肠剂量限制，调强放疗产生的毒性低于三维适形放疗。
