BMC Cancer 2009, 9:421 http://www.biomedcentral.com/1471-2407/9/421 Table 5: Diagnostic profiles of VEGF levels available before second and third cycles of chemotherapy for the prediction of cancer progression or response to therapy Evaluation 1 (R + NC vs P) VEGF BV2 VEGF BV3 Evaluation 2 (R vs NC + P) VEGF BV2 VEGF BV3 AUC (95% CI) Cut-off VEGF (pg/mL) 0.805 (0.675-0.935) 0.895 (0.797-0.993) 0.724 (0.553-0.893) 0.817 (0.679-0.956) 312.6 355.4 232.1 261.0 Sensitivity % (95% CI) 71.4 (42.0-90.4) 85.7 (56.2-97.5) 76.9 (55.9-90.2) 76.9 (55.9-90.2) Specificity % (95% CI) 71.4 (51.1-86.0) 89.3 (70.6-97.2) 75.0 (47.4-91.7) 75.0 (47.4-91.7) LR 2.5 8.0 3.1 3.1 BV2, and BV3, baseline VEGF levels before therapy cycle 2 to 3, respectively; AUC, area under receiver operating characteristic (ROC) curve; 95% CI, 95% confidence interval; LR, likelihood ratio; R, remission; NC, no change; P, progression. cantly higher in patients with tumor size >3 cm (339.9 pg/ mL (218.0-484.5 pg/mL) as compared to patients with tumor size <3 cm (172.4 pg/mL (93.0-262.0); p < 0.001). Plasma VEGF levels were found to be higher in patients with poor performance status (PS), i.e. with a PS 2-3 com- pared to those with PS of 1 and in patients with higher nodal status (N2-N3) than those with N0-N1. However, these levels did not achieve statistical significance (p = 0.062 for PS and p = 0.082 for nodal status). There was no association between plasma VEGF levels and age, sex, smoking and tobacco habits, histology, and stage (Table 2). Discussion Tumor cells secrete and synthesize a number of ang- iogenic factors which play an important role in tumor proliferation, spread and metastasis. VEGF, one of the most potent angiogenic factors, plays a central role in the regulation of tumor angiogenesis. The current interest in targeted therapies against VEGF and its receptors has gen- erated the need to study the course of this circulating ang- iogenic protein molecule during chemotherapy, to find out whether VEGF can be used in predicting prognosis and in monitoring response to therapy. Previously, some tumor biomarkers, including CYFRA 21-1, CEA and nucleosomes [4-9] have been used for predicting progno- sis and estimating response to therapy. However, till date, none of them have been validated in a clinical setting. To the best of our knowledge, this is the first study which reports the kinetics of circulating VEGF levels during the course of chemotherapy in an effort to predict insufficient response to therapy and disease progression at an early stage. In this study, we analyzed the course of circulating plasma VEGF levels at three different time points in 42 advanced stage NSCLC patients receiving platinum-based chemo- therapy. VEGF levels were measured before first (BV1), second (BV2) and third (BV3) therapy cycle. These levels were then correlated with available clinical information to know whether VEGF levels could predict insufficient ther- apy response or disease progression. We found that patients with remission had significantly lower VEGF lev- els at BV2 and BV3 as compared to patients with no change or progression. However, at BV1, patients who went into remission had higher VEGF levels than those with no change or progression. Further, to correlate any change in VEGF levels with therapeutic response, the kinetics of VEGF levels during the course of chemotherapy was monitored. We observed a stronger decrease in VEGF levels from cycle 1 to 2 (BV1-2), from cycle 1 to 3 (BV1-3), and from cycle 2 to 3 (BV2-3) in patients with remission when compared to those with no change or progression. Our results with VEGF are in accordance with the hypoth- esis that, when monitoring the efficacy of cytotoxic ther- apy, a substantial decrease in the levels of tumor marker often correlates with response to therapy whereas an increase or an insufficient decrease are generally associ- ated with no response or disease progression. In our study, it was noteworthy that a significant difference in VEGF levels was observed in the response group before the start of the second therapy cycle. In a few patients who went into remission, we observed a step fall in VEGF levels to just above the reference range within this short time frame. This decrease in VEGF levels in responders may be due to the effect of cytotoxic agents on tumor cells, either by killing them or by reduction of cellular turnover, lead- ing to a decrease in the number of cells synthesizing and secreting various angiogenic proteins, including VEGF. In this study, it was decided to evaluate VEGF levels after 2 weeks of first and second chemotherapy cycle. At such time points, it could be expected that no significant drug levels would be in circulation and that therefore, VEGF levels will reflect angiogenic activity of the residual tumor mass. There are few studies which measured serum VEGF levels before and after chemotherapy and the data is conflicting. In a cohort of 29 patients with lung cancer, serum VEGF levels were measured before and after cisplatin-based chemotherapy [12]. A significant decrease in VEGF levels Page 8 of 12 (page number not for citation purposes)