PURPOSE: The goals of this study were to determine if single-nucleotide polymorphisms in DNA damage repair genes and cell cycle regulating genes affect clinical response to combined gemcitabine radiation therapy and the overall survival (OS) of patients with pancreatic cancer. EXPERIMENTAL DESIGN: We evaluated six single-nucleotide polymorphisms of the ATM, ATM and Rad3-related (ATR), CHEK1, and CHEK2 genes in 119 patients with potentially resectable pancreatic cancer who were enrolled in clinical trials at The University of Texas M. D. Anderson Cancer Center from February 1999 to January 2006, with follow-up until February 2007. Patients received neoadjuvant concurrent gemcitabine and radiation therapy with or without gemcitabine-cisplatin induction therapy. Genotypes were determined and tested for associations with OS by Kaplan-Meier estimation, the log-rank test, and Cox regression analysis. P values of