中文摘要：

目的探讨VMAT在局部进展期直肠癌（LARC）新辅助放化疗（NCR）中的可行性。方法回顾分析2011—2013年本院行术前NCRT＋手术±术后化疗的162例LARC患者，男113例、女49例，年龄23～84岁（中位数56岁）。临床分期为Ⅱa、Ⅱb、Ⅱc期分别为22、11、5例，Ⅲa、Ⅲb、Ⅲc期分别为1、58、65例。放疗均使用了单弧VMAT，PTV150Gy分25次，PTV246Gy分25次。主要化疗方案为Xelox方案（卡培他滨1000mg／m2＋奥沙利铂100mg／m2或130mg／m2），均接受诱导及同期化疗（中位数3程）。结果所有患者均完成放疗计划，仅2例因3级腹泻中断放疗。放化疗期间全组累计3级血液学及非血液学不良反应发生率分别为9．3％与16．0％。患者距放疗结束后34～86d（中位数53．5d）手术，术后pCR率30．2％，R0切除率100％，低位直肠癌保肛率45．9％。术后不良反应累计发生率16．7％，术后30d内无死亡病例。T、N期及临床分期降期率分别为85．2％、87．1％及88．9％。结论VMAT用于LARC术前放化疗安全可行，但对长期生存影响尚需进一步观察。

英文摘要：

Objective To investigate the feasibility of preoperative neoadjuvant chemoradiotherapy （NCRT） based on volumetric modulated arc therapy （VMAT） for locally advanced rectal cancer （LARC）. Methods A retrospective analysis was performed on 162 patients with LARC who received NCRT plus surgery （and postoperative chemotherapy） in our hospital from April 2011 to April 2013. These patients included 113 males and 49 females, with a median age of 56 years （23--84 years）. Of all patients, 22, 11, and 5 had stage Ⅱa,Ⅱb,and Ⅱc disease, respectively, and 1,58, and 65 had stage Ⅲa, Ⅲb, and Ⅲc disease, respectively. All patients received single-arc VMAT, with target doses of 50 Gy/25 fractions for PTV1 and 46 Gy/25 fractions for FFV2, as well as induction and concurrent chemotherapy （ median 3 cycles）, with Xelox regimen （capecitabine 1000 mg/m2 plus oxaliplatin 100 mg/m2 or 130 mg/m2） as the main chemotherapy protocol. Results All patients received radiotherapy, and only 2 of them discontinued radiotherapy due to grade 3 diarrhea. The overall incidence rates of grade 3 hematological and non- hematological toxicities among all patients during chemoradiotherapy were 9.3% and 16. 0%, respectively. Surgery was performed after a median interval of 53.5 days （34-86 days）. After surgery, the pathological complete response rate, R0 resection rate, and sphincter preservation rate for low rectal cancer were 30. 2%, 100%, and 45.9%, respectively. Among all patients, 16. 7% developed postoperative complications, and no one died within 30 days after surgery;85.2%, 87. 1%, and 88. 9% showed decreases in T stage, N stage, and clinical stage, respectively. Conclusions Preoperative NCRT based on VMAT for LARC is safe and feasible, but its effect on long-term survival needs further observation.