The AUC value for change in BDNF level in patients without HPD was 0.72 (95% CI, 0.58-0.87; P = .007); for patients with ESCC, 0.56 (95% CI, 0.17-0.94; P = .76); for patients with CRC, 0.70 (95% CI, 0.40-1.00; P = .24); for patients with GC, 0.92 (95% CI, 0.75-1.08; P = .01) (eFigure 5I-L in the Supplement). Here, BDNF is linked to gastric cancer.