DNA polymerase β mutations and survival of patients with esophageal squamous cell carcinoma in Linzhou City, China.

Linzhou City in northern China has a high incidence of esophageal squamous cell carcinoma (ESCC). This study retrospectively analyzed the data of 231 cases with ESCC collected from 1998 to 2012. Mutations of DNA polymerase β (polβ) gene in the ESCC samples from patients in Linzhou City were examined by amplifying polβ cDNA by RT-PCR followed by cloning and sequencing. Mutations in polβ were found in 105 cases (45.9%). Nine types of mutations were identified in the polβ cDNA; the most common were 177–234 nt deletion (11.3%), 462 nt G → T (9.1%), and 648 nt G → C (6.9%). Mutations in polβ appeared to be associated with TNM status (P = 0.048). Follow-up data was used for survival analysis. The overall 5-year survival rate of the 231 patients was 37.4%; the rate for patients with wild-type (WT) polβ was 41.8%. Compared with the WT polβ group, the median survival for patients with specific mutations (177–234 nt deletion, 462 nt G → T, or 613 nt A → T) was significantly shorter (all P = 0.000), and the 5-year survival rate decreased to 0%. Patients with the 648 nt G → C mutation had improved survival (P = 0.000) with a 5-year survival rate of 100%. Our results identified nine types of mutations within polβ cDNA in ESCC patients with four mutations related to patient survival.