Kupert et al. BMC Cancer 2011, 11:513 http://www.biomedcentral.com/1471-2407/11/513 Page 8 of 10 Figure 3 IHC analysis of sPLA2-IIa expression in lung cancer specimens. Brown staining indicates positivity for sPLA2-IIa. a-e. All primary and metastatic tumors indicate positive staining for sPLA2-IIa (solid arrow). g. Some endothelial cells in new blood vessels (open arrow) and macrophages show positive staining for sPLA2-IIa in inflammatory pseudo tumor. Atypical carcinoid (f) and normal lung (h) tissue are negative staining for sPLA2-IIa. (i) sPLA2-IIa overexpression was found in the spontaneous mouse lung cancer specimens of SP-C/TAg transgenic mice (solid arrow), but not in the adjacent normal type I and II epithelial cells (open arrow) and reduce the number of CT scan and radiation exposure. Conclusions This study uncovered that plasma sPLA2-IIa is a poten- tial biomarker for lung cancer. sPLA2-IIa in combina- tion with lung cancer biomarkers Cyfra 21.1 and CEA will help with the decision algorithm for diagnosis of an early stage lung cancer in patients with SPNs and poor prognosis. Application of this combined biomarker test will increase lung cancer survival, reduce painful and costly resection of SPN, and reduce radiation exposure by repeated CT exam for SPN patients. Additional material Additional file 1: Plasma sPLA2-IIa level in healthy donors. Additional file 2: The levels of plasma sPLA2-IIa, Cyfra21.1, and CEA in lung cancer patients from the BNLCC. Additional file 3: The levels of plasma sPLA2-IIa in lung cancer patients from the GELCC. Additional file 4: Plasma sPLA2-IIa, Cyfra21.1, and CEA levels and diagnosis in patients with benign SPNs from BNLCC. Abbreviations sPLA2-IIa: Secretory phospholipase A2 group IIa; SPNs: Solitary pulmonary nodules; NSCLC: Non-small cell lung cancer; SCLC: Small cell lung cancer; Cyfra 21.1: Cytokeratin-19 fragment; CEA: Carcinoembryonic antigen; NSE: Neuron-specific enolase; ROC: Receiver operating characteristic; LDCT: Low dose spiral computed tomography Acknowledgements and funding Supported by grants from University of Cincinnati Cancer Center Foundation and NIH grants R01 CA119935 and CA131137. UC cancer center tissue bank. Patent pending: 35 U.S.C. §119.