Pancreatic ductal adenocarcinoma (PDAC) is the most common epithelial, exocrine pancreatic malignancy, accounting for more than 80 % of the malignant neoplasms of the pancreas. Although the molecular basis of pancreatic cancer is now better understood than ever before, there remains a long distance from being completely understood. In this study, we identified the differentially expressed genes (DEGs) in PDAC tissue compared with normal tissue and constructed a co-expression network by computing the pairwise correlation coefficient between the DEGs. We applied a statistical approach of MCODE to cluster genes in the coexpression network. Ten functional modules were identified in this network. Our results strongly suggest that dysregulations of immune response, homeostasis and cell adhesion may significantly contribute to the development and progression of PDAC. Results from this study will provide the groundwork for the understanding of PDAC. Future studies are needed to confirm some of the possible interactions suggested by this study.

Many studies were published to evaluate the association between Nijmegen breakage syndrome 1 (NBS1) 657del5 polymorphism and breast cancer risk, but the results remained inconsistent. To derive a more precise estimation on the possible association, we performed a meta-analysis of previous published studies. Case-control studies on the association between NBS1 657del5 polymorphisms and breast cancer risk were included into this meta-analysis. We used the odds ratio (OR) with 95 % confidence interval (95 % CI) to assess the strength of the association. Ten studies with a total of 25,365 subjects were identified and included into this meta-analysis. Meta-analysis of those ten studies showed that there was a significant association between NBS1 657del5 polymorphisms and breast cancer risk (pooled OR = 2.66, 95 % CI 1.82-3.90, P < 0.001). The cumulative meta-analyses showed a trend of a more significant association between NBS1 657del5 polymorphisms and breast cancer risk as data accumulated by publication year. Thus, our meta-analysis suggests that there was a significant association between NBS1 657del5 polymorphisms and breast cancer risk, and NBS1 657del5 polymorphism results in an increased risk of breast cancer.