KEY POINTS
- This retrospective study included 62 patients with recurrent glioblastoma treated using magnetic resonance-guided, three-dimensional-template-assisted permanent iodine-125 seed implantation.
- Patients received prescription doses of 120–140 Gy (n = 21) or 140–160 Gy (n = 41). The two groups were treated during different periods, creating potential temporal confounding.
- Six-month objective response rates were 61.9% versus 73.2% (p = 0.362), while one-year survival was 42.9% versus 68.3% (p = 0.053) in the lower- and higher-dose groups, respectively.
- Median overall survival after brachytherapy was 11.2 months with 120–140 Gy and 13.7 months with 140–160 Gy (p = 0.001). Higher delivered dose to 90% of the target remained associated with survival after adjustment (hazard ratio per 10 Gy, 0.69; 95% confidence interval, 0.55–0.87).
- Symptomatic brain edema occurred in 9.5% versus 24.4% of patients (p = 0.195). Three grade 3 events occurred in the higher-dose group, and all edema cases improved with medical treatment.
CLINICAL TAKEAWAY
These findings support prospective evaluation of iodine-125 dose escalation in carefully selected patients with recurrent glioblastoma, not routine adoption. The small non-randomized cohorts, treatment-era separation, incomplete molecular data and numerically higher edema rate substantially limit causal interpretation.