BDNF and neoplasm: Serum levels of BDNF were significantly higher in patients with CRC with metastasis (6.78 ± 3.68 ng/mL) compared to patients without metastasis (10.30 ± 5.76 ng/mL) (p = 0.007, Table 3), suggesting that BDNF was related to tumor progression and metastasis in CRC.