摘要 目的 探讨X射线修复交叉互补基因2(XRCC2）蛋白的表达与直肠癌术前放化疗后病理反应程度的关系，评价其表达水平对直肠癌术前放疗敏感性的预测价值。 方法 收集我院2014年1月—2017年12月接受术前放化疗并行手术的直肠腺癌患者88例，采用免疫组织化学方法检测放化疗前活检和手术切除标本中XRCC2蛋白的表达水平，根据7版AJCC手册肿瘤消退级别评价患者对术前放疗的敏感性,分析放化疗前后XRCC2表达水平的变化，以及XRCC2蛋白表达水平与病人临床病理学特征及术后病理反应程度的关系。 结果 放疗敏感的患者52例，放疗抵抗患者36例，放疗敏感率为59.1%，其中病理完全缓解率为4.5%；放化疗前XRCC2蛋白表达与放化疗前TNM分期、术后肿瘤T分期相关（χ2=7.812，P＜0.05,P=0.046）；放化疗前后直肠癌组织中XRCC2蛋白表达差异无统计学意义（P＞0.05）；肿瘤病理消退单因素分析示放化疗前XRCC2蛋白表达水平与病理反应程度相关（χ2=12.041，P＜0.01），放化疗前XRCC2蛋白高表达者术后病理缓解程度低，对放疗不敏感；肿瘤病理消退多因素Logistic回归分析显示，放化疗前XRCC2蛋白表达是放疗抵抗的独立风险因素（OR=6.857,95%CI=2.120～22.176）。 结论 XRCC2蛋白表达水平与直肠癌术前放疗敏感性相关，检测活检标本中XRCC2蛋白的表达有可能对于筛选直肠癌术前放疗敏感性的患者具有重要意义。 Abstract：Objective To investigate the association of X-ray repair cross-complementing gene 2 (XRCC2) expression with the degree of pathologic response after radiotherapy before rectal cancer surgery, as well as the value of XRCC2 expression in predicting radiotherapy sensitivity before rectal cancer surgery. MethodsA total of 88 patients with rectal adenocarcinoma who underwent preoperative chemoradiotherapy and surgery in our hospital from January 2014 to December 2017 were enrolled. Immunohistochemistry was used to measure the expression of XRCC2 protein in biopsy specimens before chemoradiotherapy and surgical specimens. Sensitivity to preoperative radiotherapy was evaluated according to the tumor regression level in the seventh edition of AJCC manual. The expression of XRCC2 protein was measured before and after chemoradiotherapy, and the association of XRCC2 expression with clinicopathological features and degree of pathologic response after surgery was analyzed. ResultsOf all 88 patients, 52 were sensitive to radiotherapy and 36 were resistant to radiotherapy, resulting in a sensitivity rate of radiotherapy of 59.1%, and the rate of pathological complete response was 4.5%. The expression of XRCC2 protein before chemoradiotherapy was associated with TNM stage before chemoradiotherapy and T stage of tumor after surgery (χ2 =7.812,P<0.05,P=0.046). There was no significant change in the expression of XRCC2 protein in rectal cancer tissue after chemoradiotherapy (P>0.05). The univariate analysis of pathological regression of tumor showed that the expression of XRCC2 protein before chemoradiotherapy was associated with the degree of pathologic response (χ2=12.041,P<0.01); the patients with high expression of XRCC2 protein before chemoradiotherapy had a low degree of pathological regression after surgery and was not sensitive to radiotherapy. The multivariate Logistic regression analysis of pathological regression of tumor
