目的 探讨亚甲基四氢叶酸还原酶（MTHFR）C677T与A1298C基因多态性在卡培他滨治疗中晚期结直肠癌（CRC）患者的安全性及有效性，为临床诊治CRC提供理论依据。方法 收集经病理诊断确诊的中晚期结直肠癌患者50例，用实时荧光定量PCR仪进行MTHFR C677T与A1298C基因多态性检测，观察不同基因型之间安全性及有效性的差异。结果 MTHFR C677T的CC、CT、TT基因型频率分别为46%、40%、14%，TT基因型恶心呕吐的发生率及有效率高于CC与CT基因型，差别具有统计学意义（P<0.05）。MTHFR A1298C的AA、AC、CC基因型频率分别为60%、34%、6%，CC基因型腹泻发生率高于AA与AC基因型，差别具有统计学意义（P<0.05），MTHFR A1298 C中各基因型有效率差异无统计学意义。结论 MTHFR C677T与MTHFR A1298C基因多态性在卡培他滨治疗CRC患者具有较好的临床意义，但MTHFR A1298C与药物治疗有效率无关。

Objective To investigate the safety and efficacy of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms in advanced colorectal cancer patients treated by capecitabine. Methods Fifty patients with advanced colorectal cancer diagnosed by pathology were collected. The MTHFR C677T and A1298C polymorphisms were detected by real-time fluorescence quantitative PCR, and the differences in safety and efficacy between different genotypes were observed. Results The frequency of CC, CT and TT genotypes of MTHFR C677T were 46%, 40% and 14% respectively. The incidence of nausea and vomiting and effective rate of TT genotype were higher than those of genotype CC and CT (P<0.05).The frequencies of AA, AC and CC genotypes in MTHFR A1298C were 60%, 34% and 6%, respectively. The incidence of diarrhea in CC genotype was higher than that in AA and AC genotype (P<0.05). There was no significant difference in the genotype efficiency between MTHFR A1298 C genotypes. Conclusion MTHFR C677T and MTHFR A1298C polymorphisms in capecitabine treatment of CRC patients with good clinical significance, but there was no correlation between MTHFR A1298C and capecitabine treatment efficiency.