ObjectiveCerebral edema is a common complication of brain tumors in the perioperative period. However, there is currently no reliable and convenient method to evaluate the extent of brain edema. The objective of this study is to explore the ability of serum occludin level to predict the extent of perioperative brain edema and outcome in patients with brain tumors.MethodsThis prospective study enrolled 55 patients with brain tumors and 24 healthy controls from Sanbo Brain Hospital from June 2019 through November 2019. Serum occludin level was measured preoperatively and on postoperative day 1. Peritumoral edema was assessed preoperatively using magnetic resonance imaging. Pericavity brain edema on postoperative day 1 was evaluated using computed tomography.ResultsCompared with healthy controls, serum occludin level was higher in patients with brain tumors both preoperatively and postoperatively (P < 0.001). Serum occludin level was significantly positively correlated with the extent of brain edema preoperatively (r = 0.78, P < 0.001) and postoperatively (r = 0.59, P < 0.001). At an optimal cutoff of 3.015 ng/mL, preoperative serum occludin level discriminated between mild and severe preoperative brain edema with a sensitivity of 90.48% and a specificity of 84.62%. At an optimal cutoff value of 3.033 ng/mL, postoperative serum occludin level distinguished between mild and severe postoperative brain edema with a sensitivity of 97.30% and a specificity of 55.56%. ConclusionsSerum occludin level is associated with cerebral edema and could potentially be used as a biomarker for perioperative cerebral edema.