A mediation analysis of laboratory indicators affecting seed migration after 125I brachytherapy in hepatic malignancies.

BACKGROUND

125I seed migration is a persistent safety concern in hepatic brachytherapy. Inflammatory and metabolic biomarkers may influence both tissue vulnerability and implantation strategies, contributing to migration risk.

METHODS

In this retrospective study of 625 patients undergoing 125I seed implantation for primary or metastatic liver tumors, clinical, laboratory, and procedural data were analyzed. Migration was assessed via follow-up chest radiography or CT. Univariate and multivariate Cox regression identified predictors of migration. Kaplan-Meier analysis evaluated seed migration-free survival (SMFS). Causal mediation analysis examined whether procedural factors-total number of seeds implanted (NSI) and maximum number per session (MAX)-mediated the effects of lactate dehydrogenase (LDH), neutrophil ratio, and lymphocyte ratio on migration.

RESULTS

Seed migration occurred in 134 patients (21.4%). Elevated LDH, neutrophil ratio, MAX, and NSI were significantly associated with migration (all p < 0.01), while higher lymphocyte ratio was protective. Cox regression identified LDH, MAX, lymphocyte ratio, platelet count, and NSI as independent predictors. Kaplan-Meier analysis showed shorter SMFS in patients with high LDH or neutrophils and low lymphocytes. Mediation analysis revealed that LDH and neutrophils increased migration risk both directly and indirectly through procedural intensity (MAX, NSI), whereas lymphocytes had protective effects via both pathways.

CONCLUSION

Systemic inflammation and metabolic status influence both physiologic susceptibility and procedural factors associated with 125I seed migration. Causal mediation analysis highlights modifiable indirect mechanisms, supporting personalized implantation planning to reduce migration risk.