局部进展期直肠癌术前3DCRT或VMAT同期化疗后肠壁残余癌细胞分布比较

A comparative study of distribution of residual cancer cells in the bowel wall after preoperative three-dimensional conformal radiotherapy versus volumetric modulated arc therapy with concurrent chemotherapy in treatment of locally advanced rectum cancer

目的 比较术前3DCRT或VMAT＋化疗后肠壁各层残余癌细胞（RCC）分布,明确不同放疗技术对其分布影响。方法 收集2007—2013年中山大学肿瘤防治中心诊治、行术前3DCRT （46 Gy分23次）或VMAT （50 Gy分25次）＋同期化疗及手术的局部进展期直肠癌334例,其中3DCRT 172例、VMAT 162例。两组临床Ⅱ、Ⅲ期构成相似。对所有手术标本肠壁各层RCC行病理评价。组间率差异比较采用χ^2检验或Fisher′s精确概率法。结果 术后两组各ypT、ypN、ypTNM分期均相近（P均〉0.05）。226例ypT2-4期患者黏膜层、黏膜下层、固有肌层、浆膜层或外膜层所含RCC比例分别为34.1%、43.8%、73.5%、69.0%。ypT2-4、pN （＋）、cN （＋）、cT4期3DCRT组黏膜层及黏膜下层RCC比例均高于VMAT组[47.9%∶18.1%、54.5%∶17.2%、39.8%%∶15.3%、41.3%∶14.3%（P=0.000,0.001,0.000,0.000）及50.4%∶36.2%、56.8%∶27.6%、43.0%∶26.6%、45.3%∶27.5%（P=0.032,0.014,0.006,0.017）];pN0、cT3期3DCRT组黏膜层RCC比例高于VMAT组（28.1%∶12.9%、29.5%∶13.2%,P=0.002、0.015）;两组间固有肌层、浆膜层或外膜层RCC比例在ypT2-4、pN0或pN （＋）、cT3或cT4、cN0或cN （＋）期差异均无统计学意义（P均〉0.05）。

Objective To compare the distribution of residual cancer cells （RCC） in each layer of bowl wall after preoperative three-dimensional conformal radiotherapy （3DCRT） versus volumetric modulated arc therapy （VMAT） combined with concurrent chemotherapy,and to investigate the effect of different radiotherapy techniques on the distribution of RCC. Methods A total of 334 patients with locally advanced rectum cancer （LARC） who were admitted to our hospital from May 2007 to April 2013 were enrolled as subjects. In those patients,172 received preoperative 3DCRT （46 Gy/23 F） with concurrent chemotherapy and 162 received VMAT （50 Gy/25 F） with concurrent chemotherapy. There was no significant difference in the distribution of clinical stage Ⅱ or Ⅲ between the 3DCRT group and VMAT group. All the RCCs in different layers of surgical specimens were evaluated pathologically. Between-group comparison of data was made by Pearson Chi-Square and Fisher′s exact test. Results There were no significant differences in ypT,ypN,or ypTNM staging between the two groups （P values〉0.05）.In the 226 patients with ypT2-4 disease,the proportion of RCC in the mucosa,submucosa,muscularis propria,and subserosa/perirectal fat was 34.1%,43.8%,73.5%,and 69.0%,respectively. In patients with ypT2-4,pN＋,cN＋,or cT4 disease,compared with the VMAT group,the 3DCRT group had significantly higher proportion of RCCs in the mucosa （47.9% vs. 18.1%,54.5% vs. 17.2%,39.8% vs. 15.3%,41.3% vs. 14.3%;P=0.000,0.001,0.000,0.000） and submucosa （50.4% vs. 36.2%,56.8% vs. 27.6%,43.0% vs.26.6%,45.3% vs. 27.5%;P=0.032,0.014,0.006,0.017）.In patients with pN0 or cT3 disease,the 3DCRT group had a significantly higher proportion of RCCs in the mucosa than the VMAT group （28.1% vs. 12.9%,P=0.002;29.5% vs. 13.2%, P=0.015）.In patients with ypT2-4,pN0/pN＋,cT3/cT4,or cN0/cN＋ disease,there were no significant differences in the proportion of RCCs in the muscularis propria or subserosa/perirectal fat between the two groups （P values〉0.05）. Conclusions After neoadjuvant chemoradiotherapy,most RCCs reside in the muscularis propria and subserosa/perirectal fat of the bowl wall. There are no significant differences in the distribution of most RCCs in the bowel wall or postoperative pathological staging between patients undergoing different radiotherapy techniques.