Department of Radiotherapy and Radiooncology, University Medical Center, Göttingen, Germany.
Radiother Oncol. 2012 Jan;102(1):30-7. doi: 10.1016/j.radonc.2011.10.018. Epub 2011 Nov 21.
Ongoing clinical trials aim to improve local control and overall survival rates by intensification of therapy regimen for patients with locally advanced rectal cancer. It is well known that whenever treatment is intensified, risk of therapy-related toxicity rises. An irradiation with protons could possibly present an approach to solve this dilemma by lowering the exposure to the organs-at-risk (OAR) without compromising tumor response.
Twenty five consecutive patients were treated from 04/2009 to 5/2010. For all patients, four different treatment plans including protons, RapidArc, IMRT and 3D-conformal-technique were retrospectively calculated and analyzed according to dosimetric aspects.
Detailed DVH-analyses revealed that protons clearly reduced the dose to the OAR and entire normal tissue when compared to other techniques. Furthermore, the conformity index was significantly better and target volumes were covered consistent with the ICRU guidelines.
Planning results suggest that treatment with protons can improve the therapeutic tolerance for the irradiation of rectal cancer, particularly for patients scheduled for an irradiation with an intensified chemotherapy regimen and identified to be at high risk for acute therapy-related toxicity. However, clinical experiences and long-term observation are needed to assess tumor response and related toxicity rates.
目前正在进行的临床试验旨在通过强化治疗方案来提高局部晚期直肠癌患者的局部控制率和总生存率。众所周知，治疗强度增加时，治疗相关毒性的风险也会增加。质子放疗可能是解决这一困境的一种方法，它可以在不影响肿瘤反应的情况下降低对危及器官（OAR）的暴露。
2009 年 4 月至 2010 年 5 月，连续收治了 25 例患者。对所有患者，根据剂量学方面，回顾性地计算和分析了包括质子、RapidArc、IMRT 和 3D-适形技术在内的四种不同的治疗计划。
详细的剂量体积直方图分析表明，与其他技术相比，质子治疗明显降低了 OAR 和整个正常组织的剂量。此外，适形性指数显著提高，靶区覆盖符合 ICRU 指南。
计划结果表明，质子治疗可以提高直肠癌放疗的治疗耐受性，特别是对于计划接受强化化疗方案放疗且有发生急性治疗相关毒性高风险的患者。然而，需要临床经验和长期观察来评估肿瘤反应和相关毒性发生率。
