放疗后直肠癌组织病理变化

A histopathological comparison of changes after neo-adjuvant radiotherapy in rectal cancer

目的：观察直肠癌术前放疗后组织病理学变化。方法：pTNM Ⅱ期和Ⅲ期直肠癌患者80例，分为对照组和放疗组。每组40例。放疗组使用西门子M6740直线加速器，采用前后对穿射野和等中心剂量，总剂量40Gy，每次剂量为2Gy，共20次，放疗结束后1～2周手术。对照组直接手术治疗。治疗前后在直视下分别钳取距癌灶2cm的正常黏膜和肿瘤组织，经常规处理后进行病理组织学观察。结果：放疗组患者中，按直肠癌消退分级（RCRG）分为1级者14例（35．0％）、2级者18例（45．0％）、3级者8例（20．0％）。放疗组Ⅱ级以上癌组织坏死为72．5％，对照组为45．0％（P〈0．01）；放疗组Ⅱ级以上间质组织纤维化变性和血管内膜增厚分别为80．0％和77．5％，而对照组分别为20．0％和40．0％（P〈0．01）。结论：直肠癌术前放疗可使癌组织坏死，癌组织和间质产生纤维变性，降低肿瘤分期，有利于肿瘤的切除。

Objective： To compare the histopathological changes after neo-adjuvant radiotherapy and to elucidate the mechanism of radiotherapy in rectal cancer. Methods： 80 patients with rectal cancer in pTNM stage Ⅱ or Ⅲ were enrolled between April 2000 and December 2002. They were randomly assigned to surgery alone or preoperative neo-adjuvant radiotherapy. The conventional radiotherapy scheme was followed ： 40 Gy in 2.0 Gy fractions. The treatment last 4 weeks and it is usually followed by an interval of 1-2 weeks before the operation. Pathological changes including necrosis of tumor and changes of matrix and vessels were graded. Results： Significant tumor regression （ RCRG 1 ） was seen in 14 cases （35 percent） after radiotherapy, while partially tumor regression （ RCRG 2） was seen in 18 cases （45 percent）. Significant necrosis was observed in 72.5 percent of cases after preoperative radiotherapy, most foci of adenocarcinoma were replaced by fibrosis in 80 percent of cases, and intimal thickening in most of the vessels were seen in 77.5 percent of cases. The frequency of these pathological changes after radiotherapy was significantly more than control group. Conclusion： Necrosis, fibrosis and thickening of vascular intima in the rectal cancer tissue after radiotherapy is more frequent than those without radiotherapy. It may be the potential reason for increased resection rate and sphincter-saving after radiotherapy.