中低位直肠癌新辅助放化疗后安全手术切缘的临床病理研究

Clinicopathologicai study of safe resectional margin in mid and low rectal cancer after neoadjuvant chemoradiotherapy

目的探究中低位直肠癌新辅助放化疗后肿瘤退缩规律，为直肠癌手术合理切除范围提供病理学依据。方法收集2009年1月至2012年6月间在陕西省人民医院接受术前新辅助放化疗加根治性手术的40例进展期中低位直肠癌患者的新鲜手术标本，纵行连续切片进行病理检测．判断肿瘤组织学反应情况。采用细胞角蛋白免疫组织化学方法于显微镜下测量残余肿瘤在直肠肛侧黏膜下浸润距离以及残余肿瘤细胞空间分布特征；采用Ki-67免疫组织化学染色方法评估残存肿瘤细胞增殖活性。结果40例患者新辅助放化疗后获完全反应者5例（12．5％），中度反应19例（47．5％），轻度反应9例（22．5％），反应不良7例（17．5％）。新鲜直肠肠壁标本经病理学制片后，标本收缩率平均为18％。残存肿瘤细胞Ki-67增殖指数较放化疗前明显降低（P〈0．01）。以残余溃疡或瘢痕下缘为参照点，肠壁内癌逆向浸润平均距离为（6．1±4．7）mm；其中最远1例为11．0mm，根据病理制片收缩率换算，未受牵张的新鲜标本为13．0mm。残存肿瘤细胞散在分布于溃疡、纤维瘢痕组织周围，其空间分布呈向心性退缩。结论中低位直肠癌患者接受新辅助放化疗后，其肿瘤具有不同程度的退缩，残余溃疡或瘢痕组织内存在增殖活性肿瘤细胞。术中应在体切除肿瘤下方肠壁2em：环周切除范围应以完整切除肿瘤区域残余瘢痕组织为度。

Objectives To investigate the regression pattern of mid and low rectal cancer treated with neoadjuvant ehemoradiotherapy and then to provide the pathological proofs for reasonable resectional margin in rectal cancer surgery. Methods Forty cases of mid and low rectal cancer patients received concurrent chemoradiotherapy and then underwent radical operation. The whole-mount serial sections of resected rectal cancer specimen were stained with cytokeratin antibody using immunohistochemieal techniques to show the reridual cancer cells under the mucosa. The microscopic measurement was performed to determine the reverse infiltration of cancer cells in the rectal wall and to describe the cancer ceils scatter ways in the cancer mass. The Ki-67 immunohistochemical stain was also performed to show the proliferation activity of residual cancer cells after neoadjuvant chemoradiotherapy. Results The length of specimen was shrinking continuously during the pathologic section production and the shrink rate was 18%. There were remanent cancer cells which showed positive Ki-67 expression and the chemoradiotherapy decreased the Ki-67 expression significantly. The lower edge of remaining ulcers or scars could be used as the reference point from which the cancer infihration could be measured. According to our measurement, the average reverse infiltration of cancer cells in uhe whole-mount section was （6.1±4.7） mm, the deepest one was 11.0 mm in the section which couhl he converted into fresh bowel length of 12.98 mm. The pathology showed that the residul cancer cells scattered in the fibrous tissue of ulcers, scars and manifested a regression of spatial distribution. Conclusions The rectal cancers show regression in different degrees after neoadjuvant chemoradiotherapy. The residual cancer cells in the fiber tissues manifest proliferation activity. The distal end of resection should be at least 2 cm away from the lower edge of ulcers or scars of primary tumor in the rectal wall in patients after neoadjuvant ehemoradiotherapy. The circumferential resection margin should include all the fihrous scar of the tumor area to ensure the remove of tumor cells completely.