Abstract: AIM: To explore the effect of single nucleotide polymorphism (SNP) of breast cancer susceptibility gene 1 (BRCA1) on chemotherapy sensitivity and survival prognosis of patients with metastatic esophageal squamous cell carcinoma. METHODS: A total of 153 patients with newly treated metastatic esophageal squamous cell carcinoma who were admitted to Suzhou Science and Technology City Hospital from June 2016 to February 2020 were included and administered with cisplatin combined with capecitabine chemotherapy. Before the first chemotherapy, 5 mL of venous blood was collected to extract DNA, and the TaqMan probe method was used to detect the genotypes of the BRCA1 gene rs8176318G/T, rs799917T/C and rs1799966T/C polymorphic loci. The objective response rate (ORR) and overall survival (OS) of different genotypes were analyzed. RESULTS: Rs799917T/C polymorphism was closely related to the chemosensitivity of metastatic esophageal squamous cell carcinoma. The chemotherapy response rates of TT, TC and CC genotypes increased gradually (TT 22.5%, TC 38.6%, CC 55.3%, χ2 = 8.041, P=0.018). The chemotherapy response rate of the CC genotype was 4.154 times that of the TT genotype (95%CI: 1.54911.141, χ2=8.007, P=0.005); the chemotherapy response rate of the TC+CC genotype was 2.678 times that of the TT genotype (95%CI: 1.1606.179, χ2=5.329, P=0.021). KaplanMeier analysis showed that the rs1799966T/C polymorphism was related to the survival time of patients, and the median OS of carriers of TT, TC and CC genotypes showed a gradually prolonging trend (TT 8.5 months, TC 12.1 months, CC 13.8 months, χ2 =11.864, P=0.003); The median OS of patients with TC+CC genotype was 12.6 months, which was significantly longer than that in the TT group (χ2=10.515, P=0.001). COX regression model analysis showed that the polymorphism of rs1799966T/C was still an independent prognostic factor of OS. There was no statistical correlation between rs8176318G/T polymorphism, chemotherapy response and prognosis. CONCLUSION: The rs799917 polymorphism of BRCA1 gene is associated with the sensitivity of cisplatin combined with capecitabine in metastatic esophageal squamous cell carcinoma, and rs1799966 polymorphism may affect the prognosis of patients.

Key words: breast cancer susceptibility gene1, polymorphism, esophageal squamous cell carcinoma, chemotherapy, prognosis