Serum uric acid level can predict asymptomatic brain metastasis at diagnosis in patients with small cell lung cancer.

Background: The aim of this study was to determine the relationship between serum uric acid level at diagnosis and asymptomatic brain metastasis in patients with extensive-stage small cell lung cancer.

Methods: A total of 69 patients with extensive-stage small cell lung cancer without symptomatic brain metastases, whose serum uric acid level was measured at the time of diagnosis, were included in this retrospective cross-sectional study. The patients were divided into two groups as those with and without asymptomatic brain metastases. The Mann-Whitney U test was used for comparison between groups, and Spearman's correlation test was used for correlation analysis. The cut-off level of serum uric acid level was analyzed, and sensitivity, specificity, and accuracy rates were determined for brain metastasis. Independent factors affecting asymptomatic brain metastasis were determined by multivariate Cox regression analysis.

Results: The median serum uric acid level of all patients was 6.9 mg/dL. Twenty-two percent of patients had asymptomatic brain metastases, and serum uric acid levels were significantly higher in these patients (P = 0.0014). The cut-off value for serum uric acid level was calculated as 6.2 mg/dL. The sensitivity, specificity, and accuracy of this value for brain metastasis were 84%, 76%, and 78%, respectively. High serum uric acid level was an independent risk factor for asymptomatic brain metastasis (OR 3.446 95% CI 1.337-5.480; P = 0.005).

Conclusion: In conclusion, a serum uric acid level of 6.2 mg/dL and above at the time of diagnosis may predict asymptomatic brain metastasis in patients.