Fan et al. BMC Cancer 2011, 11:320 http://www.biomedcentral.com/1471-2407/11/320 3Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China. Authors’ contributions LF performed the statistical analysis and drafted the manuscript. FH carried out immunohistochemistry staining and drafted the manuscript. HL helped to revise the draft. JZ and YL participated in collecting the samples. ZY carried out the figures and tables. LW and YG participated in the follow-up study. ZW and QY helped to confirm the diagnosis of the samples. GH conceived the study, and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. Received: 30 December 2010 Accepted: 29 July 2011 Published: 29 July 2011 References 1. 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