Abstract: To investigate the association of single nucleotide polymorphisms of (manganese superoxide dismutase, MnSOD) gene with radiosensitivity of esophageal squamous cell carcinoma. METHODS： The MnSOD Ala16Val was genotyped by polymerase-chain reaction-restriction fragment length polymorphism(PCR-RFLP) analysis in 93 esophageal squamous cell carcinoma patients. All patients received 3D-CRT or the conventional radiotherapy. RESULTS: The frequencies of T/T and C/T+C/C allelotype among three grades of curative effect were 59.1%, 40.9%; 77.8%, 22.2%; 62.5%, 37.5% respectively. There was no statistical difference in allelotype distribution between three grades. When the length of esophagus cancer was 5 cm or less than there was no statistical difference in allelotype distribution between three grades of curative effect. But when the length was more than 5 cm a significant difference was observed in the MnSOD allelotype distribution among different length (χ2=2.658, P＜0.05). The curative effect of radiotherapy in patients with C/T+C/C allelotype was better than patients with allelotype T/T when the length was more than 5 cm. There was no difference of MST and 1-year survival rates in patients with MnSOD-9 T/T genotype and MnSOD-9 T/C＋C/C genotype(17 months, 68%, 35.82% vs 22 months, 73%,34.62% P > 0.05). CONCLUSION： The MnSOD Ala16Val appears to be associated with an improved radiosensitivity in patients when the length of esophagus lesion was more than 5 cm.

Key words: esophageal squamous cell carcinoma, manganese superoxide dismutase, single nucleotide polymorphism, radiosensitivity, curative effect