BMC Cancer 2009, 9:421 http://www.biomedcentral.com/1471-2407/9/421 ) L m / g p ( F G E V FDiigsturribeu2tion of plasma VEGF levels in various response groups Distribution of plasma VEGF levels in various response groups. Median and interquartile range along with minimum and maximum values and outliers of the baseline values of the VEGF before start of therapy cycle 1 (pre-treatment; BV1), cycle 2 (BV2), and cycle 3 (BV3) are given. To achieve optimum sensitivity and specificity, a VEGF concentration in patients that did not overlap with the control VEGF value would be ideal. Receiver-operating characteristics (ROC) curve was, therefore, generated for calculating the sensitivity and specificity of VEGF as a tumor marker at a selected cut-off value. The cut-off value of plasma VEGF levels was determined as 145.4 pg/mL using the ROC analysis (area under the curve = 0.8799; standard error = 0.0213; 95% CI = 0.8381-0.9216; Figure 5). At this cut-off, plasma levels of VEGF reached a sensi- tivity of 79.8% and a specificity of 79.0% for the detection of NSCLC. Further, at 95% specificity, we could detect NSCLC with a sensitivity of 59.7% (VEGF cut-off = 237.0 pg/mL). Circulating plasma VEGF levels in correlation with various clinicopathological factors The relationships between various clinicopathological factors and plasma VEGF levels in the patients with lung cancer are shown in Table 2. VEGF levels were signifi- Page 7 of 12 (page number not for citation purposes)