局部进展期直肠癌的放疗规范及其进展

Radiotherapy standard and progress in locally advanced rectal cancer

目前直肠癌新辅助治疗模式的优化主要包括以下两个方面：（1）通过提高新辅助治疗阶段的治疗强度，包括增加放疗剂量、增加同期化疗强度或将辅助化疗前移，有可能提高病理完全缓解（pCR）率及降低远处转移率；（2）通过短程放疗或是单纯新辅助化疗在保证疗效的情况下，能够降低治疗毒性，增加患者耐受性。对于局部进展期直肠癌，长程的新辅助放化疗是目前的标准治疗方案。目前指南并不推荐放疗期间应用联合化疗方案，但若能筛选出从联合化疗中获益的患者，对于指导直肠癌的个体化治疗意义重大。目前NCCN指南推荐短程放疗可用于R或N＋期的直肠癌，但不推荐T4期患者做短程放疗：在ESMO指南中，对于MRI评估为中危的患者可选择短程放疗或常规放化疗，对于T4期或直肠系膜筋膜（MRF）阳性的高危患者则不推荐做短程放疗。在NCCN指南推荐中，新辅助化疗-放化疗-手术-辅助化疗也可作为治疗选择。将辅助化疗提前，甚至在手术前完成全部新辅助治疗，是否能提高患者对治疗的耐受性，同时不影响治疗疗效？目前对于这一问题的研究均为二期研究，尚需最终结果来证实。

Recently, treatment strategy optimization tbr neoadjuvant therapy of rectal cancer includes two aspects： （1） Increasing treatment intensity may improve pathological complete response rate, including increasing radiation dose or concurrent chemotherapy intensity, or shifting adjuvant chemotherapy ; （2） Short-course radiotherapy or neoadjuvant chemotherapy which can promise treatment efficacy will decrease toxicity and lead to better tolerance. Long-course chemoradiotherapy is the recent treatment standard for locally advanced rectal cancer. NCCN guidelines do not recommend combined chemotherapy in the radiotherapy period. However, it is important for individualized treatment of rectal cancer if appropriate patients who may benefit from the combined concurrent chemotherapy can be selected. Short-course radiotherapy is defined as 5 Gy x 5. It is recommended for T3 or N＋ rectal cancer in NCCN guidelines, but not for T4 patients. In ESMO guidelines, stratified patients of intermediate risk by MRI can be treated with either short- course or long-course radiotherapy, but short-course radiotherapy is not recommended for T4 or positive mesorectum fascia （MRF＋） patients with high risk. Neoadjuvaut chemotherapy incorporated in the neoadjuvant part has been a therapeutic choice in NCCN guidelines. However, It is still unclear whether chemotherapy upfront as a component of neoadjuvant treatment or even completion of chemotherapy before surgery can improve treatment outcome or not. There are phase II studies focused on this issue and final results are pending.