Department of Oncology, Oxford University Hospitals Trust, Oxford, UK.
Department of Oncology, Oxford University Hospitals Trust, Oxford, UK; CRUK MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
Clin Oncol (R Coll Radiol). 2020 Jan;32(1):35-42. doi: 10.1016/j.clon.2019.07.009. Epub 2019 Jul 27.
Dose-response curves suggest that higher doses of radiotherapy improve the complete response rate in rectal cancer. The UK adopted the EXPERT trial dose and fractionation, 45 Gy in 25 fractions to the pelvis with a sequential 9 Gy in five fractions to the gross tumour, in patients where the aim was to maximise the complete response. In the Oxford University Hospital NHS Foundation Trust (Oxford, UK) we deliver a biological equivalent dose (BED5) in selected patients using intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) in 25 fractions. We carried out a retrospective analysis of our series to: (i) document the toxicity of this protocol; (ii) ascertain whether dose constraints from RTOG 0822 were appropriate; (iii) assess the response.
The demographics and treatment details for all consecutive patients treated with this protocol were collected using electronic systems. Patients received 45 Gy to the elective nodes and 52 Gy using a SIB to the gross tumour with capecitabine chemotherapy using IMRT or RapidArc plans. Acute toxicity was collected prospectively during weekly reviews. For the purpose of this study, a dedicated gastrointestinal radiologist reviewed all baseline and post-treatment magnetic resonance images and assigned a magnetic resonance tumour regression grade (mrTRG).
Seventy-one patients were identified. Seventy completed radiotherapy with a median overall treatment time of 34 days (range 32-36 days); 67.6% received full-dose chemotherapy, with 21.2% receiving a reduced dose. There was a 4.2% incidence of grade 3+ non-haematological toxicity and 1.5% grade 3 + haematological toxicity. 4.2% were admitted during their radiotherapy, with one death due to a pelvic abscess. The RTOG 0822 constraints were achieved in ≥75% of cases, other than the high-dose bladder constraint. mrTRG 1-2 was seen in 47.8%, with mrTRG 1 seen in 23.9%.
We suggest that our protocol shows acceptable acute toxicity, with promising mrTRG results, and could be adopted by centres as an IMRT equivalent dose for EXPERT dose and fractionation.
剂量-反应曲线表明，更高剂量的放疗可提高直肠癌的完全缓解率。英国采用了 EXPERT 试验剂量和分割方式，即盆腔 45 Gy 共 25 次，肿瘤靶区 9 Gy 共 5 次，适用于旨在最大限度提高完全缓解率的患者。在英国牛津大学医院 NHS 基金会信托（Oxford，UK），我们在选定的患者中使用强度调制放疗（IMRT）并结合同步整合 boost（SIB）进行 25 次分割，以实现生物等效剂量（BED5）。我们对该系列患者进行了回顾性分析：（i）记录该方案的毒性；（ii）确定 RTOG 0822 的剂量限制是否合适；（iii）评估反应。
使用电子系统收集所有连续接受该方案治疗的患者的人口统计学和治疗细节。患者接受 45 Gy 选择性淋巴结照射和 52 Gy SIB 肿瘤照射，同时接受卡培他滨化疗，采用 IMRT 或 RapidArc 计划。急性毒性在每周的审查中进行前瞻性收集。为了进行这项研究，一名专门的胃肠放射科医生审查了所有基线和治疗后磁共振图像，并分配了磁共振肿瘤消退分级（mrTRG）。
确定了 71 名患者。70 名患者完成了放疗，中位总治疗时间为 34 天（范围 32-36 天）；67.6%接受了全剂量化疗，21.2%接受了减少剂量的化疗。有 4.2%的患者发生 3 级以上非血液学毒性，1.5%的患者发生 3 级以上血液学毒性。有 4.2%的患者在放疗期间住院，其中 1 例因骨盆脓肿死亡。除高剂量膀胱限制外，RTOG 0822 限制在≥75%的病例中得到满足。mrTRG 1-2 占 47.8%，mrTRG 1 占 23.9%。
我们认为我们的方案显示出可接受的急性毒性，具有有希望的 mrTRG 结果，并可以被中心采用作为 EXPERT 剂量和分割的 IMRT 等效剂量。
