The correlation between the clinicopathologic findings and serum VEGF-C levels were shown in Table 1
. There was no association between serum VEGF-C level and patient gender, lung and lobe involved, histology, and pathologic T factor. As to preoperative lymph node staging, the distribution of the results of CT scan, serum VEGF-C, and serum VEGF-C correlated with CT scan, as shown in Table 2
. Enlarged lymph nodes on CT were found in 45 patients; only 29 of them had lymph node metastasis at pathologic diagnosis. Seventy-one patients did not have enlarged lymph nodes; unexpected metastasis was found in 21 of them. The median serum VEGF-C concentration (25 to 75% quartile) was 1,768.2 pg/mL (1,180.2 to 2,782.9 pg/mL) in patients with lung cancer. The median serum VEGF-C concentration gradually increased in correspondence with pathologic T stage categories, but a statistically significant difference could not be detected: T1, 1,453.1 pg/mL (1,098.9 to 2,133.9 pg/mL); T2, 1,780.2 pg/mL (1,255.3 to 2209.4 pg/mL); T3, 1,820.2 pg/mL (1208.3 to 2387.3 pg/mL) [p = 0.337]. Patients with lymph node metastasis revealed higher serum VEGF-C concentrations than those without: 1,465.5 pg/mL (1,110.5 to 1,903.5 pg/mL) vs 2009.2 pg/mL (1,100.5 to 2,987.0 pg/mL) [p = 0.0007; Fig 1]
. No statistical difference was found between N1 and N2 category: 1,920.4 pg/mL (1,214.5 to 2350.9 pg/mL) vs 2,041.2 pg/mL (1,675.0 to 2476.5 pg/mL), respectively (p = 0.6143). Serum VEGF-C reached the highest sensitivity and specificity in diagnosing lymph node metastasis when a cut-off value of 1,850.6 pg/mL was applied.