gms | German Medical Science

Objective: The outcome and toxicity profiles of local treatment concepts for recurrent brain metastases after prior multimodal treatment are poorly defined. In this two-institutional study we retrospectively compared the outcome and toxicity profiles of salvage low-activity iodine-125 brachytherapy (SBT) with that of salvage open tumor resection (OTR) of recurrent brain metastases.

Methods: Thirty-five patients with recurrent intracranial disease, prior multimodal treatment and a Karnofsky performance score (KPS) ≥70 were considered eligible. Patients underwent either salvage OTR or SBT - after prior histological verification by means of stereotactic biopsy- at two distinct neurosurgical centers. In case of SBT exclusively temporary low activity iodine-125 seeds (activity <20 mCi, reference dose: 50 Gy, dose rate <15 cGy/h) were used. Study endpoints were postrecurrence survival (PRS) as well as local and distant tumor control rates after local salvage therapy. The date of SBT/OTR was set as the reference point. The cumulative dose applied to the early and late responding tissue of each SBT patient was assessed by calculation of the biological effective tumor dose (BED) according to the formula of Dale. CNS toxicity was assessed according to the RTOG/EORTC criteria.

Results: The SBT and the OTR cohorts did not differ in terms of their demographic parameters except for tumor size (smaller volume in the SBT group: 2.3 cm³ vs. 7.5 cm³, p=0.002). In the OTR cohort, all patients had undergone prior resection with adjuvant radiotherapy in 10 cases. In the SBT cohort, all patients had undergone prior radiotherapy (9 cases fractionated external beam radiotherapy, 14 cases focused high dose radiotherapy). PRS did not differ between the two treatment groups (PRS after one year 46.7% in the SBT group vs. 54.9% in the OTR group; p=0.7). The one-year local/distant tumor control rate after salvage SBT and OTR was similar (p=0.13 and p=0.58 respectively). In the overall analysis, brain metastases originating from pulmonary cancer had a decreased PRS compared to other primary tumor dignities and a higher risk for distant tumor relapse (p=0.04 both). One patient in the OTR group suffered from a transiently aggravated visual field defect; two patients of the SBT group with upper-range BED values suffered from RTOG/EORTC grade I/II toxicity (transient headache due to steroid-responsive edema).

Conclusion: Salvage SBT and OTR have a comparable outcome and toxicity profile. In small recurrent brain metastases, preference should be given to low-dose rate iodine SBT due to decreased hospitalization costs and time to convalescence. Brain metastases of pulmonary cancer origin appear to have a particular high risk profile for tumor relapse and should undergo closer follow-up after both salvage treatments.