Background: Neoadjuvant chemoradiotherapy (nCRT) is the standard treatment for locally advanced rectal cancer, but only 15–30% of patients achieve a pathological complete response. Single nucleotide polymorphisms represent stable genetic markers with potential predictive value for treatment response. This systematic review synthesizes current evidence on the association between SNPs and the response to nCRT in rectal cancer.Methods: PubMed and Web of Science databases were searched for relevant English studies. Two reviewers independently screened the titles and abstracts using the DistillerSR tool. Full-text articles were assessed for their eligibility. Data extraction followed the PRISMA guidelines, and the risk of bias was assessed.Results: Thirty-two studies (4116 patients) assessed 304 SNPs across 126 genes in 407 analyses. DNA repair genes (XRCC1, XRCC3, ERCC1, ERCC2) and folate metabolism genes (MTHFR, TYMS) were most frequently investigated. Only two SNPs demonstrated predictive value in multiple studies: rs25487 (XRCC1) and rs1801133 (MTHFR); however, the associations were inconsistent. The remaining SNPs showed isolated associations in single studies. No SNP demonstrated predictive value across independent cohorts.Conclusions: Current evidence does not support the clinical use of individual SNPs to predict nCRT response in rectal cancer patients. Although XRCC1 and MTHFR polymorphisms have been extensively studied, their predictive utility remains inconclusive. Future research should prioritize large, multicenter prospective studies with standardized treatment and outcome definitions, and consider polygenic risk models or integrated multi-omic approaches.
背景：新辅助放化疗（nCRT）是局部进展期直肠癌的标准治疗方案，但仅有15–30%的患者能达到病理完全缓解。单核苷酸多态性作为稳定的遗传标记物，对治疗反应具有潜在的预测价值。本系统综述综合了当前关于SNPs与直肠癌nCRT反应关联性的证据。 方法：检索PubMed和Web of Science数据库中相关的英文研究。两名评审员使用DistillerSR工具独立筛选标题和摘要，并对全文进行资格评估。数据提取遵循PRISMA指南，并对偏倚风险进行评估。 结果：32项研究（共4116例患者）在407项分析中评估了126个基因的304个SNPs。DNA修复基因（XRCC1、XRCC3、ERCC1、ERCC2）和叶酸代谢基因（MTHFR、TYMS）是研究最频繁的基因。仅有两个SNPs在多项研究中显示出预测价值：rs25487（XRCC1）和rs1801133（MTHFR），但其关联性并不一致。其余SNPs仅在单项研究中显示出孤立关联。没有任何SNP在独立队列中均表现出预测价值。 结论：现有证据不支持在临床中使用单个SNP来预测直肠癌患者的nCRT反应。尽管XRCC1和MTHFR多态性已被广泛研究，但其预测效用仍无定论。未来研究应优先开展大规模、多中心的前瞻性研究，采用标准化的治疗和结局定义，并考虑多基因风险模型或整合多组学方法。
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