Kupert et al. BMC Cancer 2011, 11:513 http://www.biomedcentral.com/1471-2407/11/513 Page 5 of 10 Figure 1 High levels of plasma sPLA2-IIa are associated with lung cancer as compared with benign lung nodule. (a) Plasma samples were diluted ten times and then subjected to ELISA analysis for sPLA2-IIa levels in duplicate of each sample. The average of the duplicate samples was calculated against to the standard curve in each experiment and presented as pg/ml sPLA2-IIa. (b) High levels of plasma sPLA2-IIa are significantly associated with T2 lung cancer relative to T1 stage lung cancer. The dotted line indicates the optimum cutoff value of 2.4 ng/ml necrotizing granulomas (Table 2). This finding indicated that active localized inflammation can occasionally lead to a moderate increased plasma sPLA2-IIa. Furthermore, our data demonstrated that there was an increased basal level of plasma sPLA2-IIa in patients with SPNs relative to those in healthy donors, which may result from SPNs and chronic inflammation. Our data strongly suggest that plasma sPLA2-IIa can serve as a biomarker to predict more than 48% of T1 stage lung cancers and up to 67% of T2 stage lung can- cer relative to patients with benign SPNs, although the plasma sPLA2-IIa is elevated occasionally in patients of benign SPNs. sPLA2-IIa is the best biomarker relative to Cyfra 21.1 and CEA, and the combined sPLA2-IIa, Cyfra 21.1 and CEA tests increase the sensitivity for lung can- cer prediction relative to sPLA2-IIa test alone. In addi- tion, plasma sPLA2-IIa may potentially serve as a poor prognosis biomarker for lung cancer. sPLA2-IIa is overexpressed in lung cancer specimens Among 100 core lung biopsies examined by IHC, sPLA2-IIa was overexpressed in 100% of squamous cell carcinoma (20 cores), adenocarcinoma (20 cores), and bronchioalveolar carcinoma (10 cores), in 70% of small cell carcinoma (10 cores), and in 90% of metastatic squamous cell carcinoma (10 cores) (Figure 3a-e), but not detected in atypical carcinoid (5 cores) (Figure 3f). sPLA2-IIa was not detected in inflammatory pseudo tumor (5 cores), tuberculosis (5 cores), and normal lung tissue (15 cores) (Figure 3g-h). Expression of sPLA2-IIa in infiltrating macrophages and endothelial cells of new blood vessels in inflammatory pseudo tumors (Figure 3g) implicated an underlying mechanism of localized inflammation as the cause of occasional elevated levels of plasma sPLA2-IIa in patients with benign lesions (Table 2). We also found that sPLA2-IIa was overex- pressed in lung cancer tissue, but not the adjacent nor- mal type I and II epithelial cells in the spontaneous mouse lung cancer from SP-C/TAg transgenic mice, in which the transgene SV40 early region (TAg) gene was driven by a 3.7 kb promoter of human surfactant pro- tein C (SP-C) gene (Figure 3i) [28,29]. These data con- firmed that sPLA1-IIa was overexpressed in lung cancer cells, but not in normal alveolar epithelial cells. Discussion With increased sensitivity of imaging technology, such as low dose spiral computed tomography (LDCT), lung cancer can be detected at an earlier stage [2]. Recently, lung cancer screening with CT has been shown to detect lung tumors earlier and decrease lung cancer mortality [30]. One of the problems with the use of CT screening is the number of false positive with up to 25% of the subjects in the lung cancer screening trials having nodules, most of which are benign. Given the epidemic of histoplasmosis in the Ohio valley, we found that among 132 people enrolled in a pilot lung cancer screening project, 61% of subjects had nodules, most of which were benign [5]. If lung cancer screening with CT becomes standard, there will be a large number of nodules that will need to be evaluated. Monitoring these nodules usually requires repeated CT scans at 3, 6, 9, 12, 24 months based on the sizes of SPNs [6]. An