中文摘要：

目的探讨新辅助放化疗对直肠癌细胞凋亡、增殖以及侵袭能力的影响，为新辅助放化疗在直肠癌中的应用提供依据。方法选取新辅助放化疗的中低位直肠癌患者（研究组）及未行新辅助放化疗的中低位直肠癌患者（对照组）术后石蜡包埋组织进行对照研究。检测与直肠癌生物学特性相关指标（如癌胚抗原、增殖细胞核抗原及血管内皮生长因子受体2）在两组之间的表达差异。结果研究组和对照组CEA在直肠癌组织中的阳性表达分别为：83．33％（50／60）、98．33％（59／60），两者比较差异有显著性（P〈0．05）；研究组和对照组PCNA在直肠癌组织中的阳性表达分别为：83．33％（50／60）、96．67％（58／60），两者比较差异有显著性（P〈0．05）；研究组和对照组VEGFR2在直肠癌组织中的阳性表达分别为：46．67％（28／60）、81．67％（49／60），两者比较差异有极显著性（P〈0．01）。结论新辅助放化疗可使直肠癌肿瘤细胞的侵袭能力降低，可能有利于直肠癌患者的预后。

英文摘要：

Objective To provide reliable support for the application of neoadjuvant therapy for advanced rectal cancer by exploring the impacts of the therapy on apoptosis, proliferation, and invasive ability of the cancer ceils. Methods Postoperative paraffin sections from patients receiving neoadjuvant therapy （ study group ） and from those receiving no neoadjuvant therapy （ control group ） were examined. The expression differences of oncobiology-associated markers including carcino-embryonic antigen （ CEA ）, proliferating cell nuclear antigen （ PCNA ）, and vascular endothelial growth factor receptor- 2 （ VEGFR2 ） were compared between the two groups. Results The positive rates of CEA, PCNA, and VEGFR2 were significantly lower in the study group than in the control group （ 98.33% vs. 83.33%, x^2 = 9.08, P= 0.028 for CEA; 96.67% vs. 83.33%, x^ 2= 9.51, P= 0.023 for PCNA; and 81.67% vs. 46.67%, x ^2= 16.32, P= 0.001 for VEGFR2 ）. Conclusions Neoadjuvant therapy can reduce the invasive ability of rectal cancer cells, which may be beneficial to the prognosis of patients with rectal cancer.