Comparison of stereotactic brachytherapy (125 iodine seeds) with stereotactic radiosurgery (LINAC) for the treatment of singular cerebral metastases.

Purpose: To compare stereotactic brachytherapy (SBT) with stereotactic radiosurgery (SRS) for treating singular cerebral metastases, regarding feasibility, complications, cerebral disease control, and survival.
Patients and Methods: For this retrospective, single-center study, all patients treated for newly diagnosed, untreated singular cerebral metastasis with SBT using (125)iodine seeds (cumulative tumor surface dose 50 Gy, applied for 42 days) were compared with patients receiving LINAC-based SRS for the same indication. Survival and actuarial local and distant disease control were evaluated using univariate Kaplan-Meier estimates and Cox regression. Results were compared using Student's t test and the χ2 test.
Results: A total of 142 patients treated with SRS were compared with 77 patients undergoing SBT. No significant differences were observed between epidemiological and disease-related features (p > 0.05), except a lower KPS (p < 0.007) and a larger tumor volume (p < 0.001) in the SBT group. Neither median survival (LINAC-SRS vs. SBT = 8.1 vs. 8.0 months, respectively) nor actuarial local/distant cerebral disease control after 12 months showed significant differences (93.6% vs. 96.7% / 42.4% vs. 46.4%). There was no treatment-related mortality and no permanent grade 3 or 4 CNS toxicity (RTOG/EORTC CNS toxicity criteria).
Conclusion: For the treatment of singular cerebral metastasis, SBT represents a safe, minimally invasive, and effective local treatment option with results comparable to SRS regarding survival and cerebral disease control. Its advantage is that it allows histological (re-)evaluation and treatment within one stereotactic procedure and, compared to microneurosurgery, is almost unrestricted regarding tumor localization. Furthermore, larger metastases can be treated than with SRS. SBT, therefore, represents an alternative local treatment in selected cases.