Clinical Outcomes of Large Brain Metastases Treated with Neurosurgical Resection and Intraoperative Cesium-131 Brachytherapy : Results of a Prospective Trial
Mené auprès de 42 patients présentant des métastases cérébrales de diamètre supérieur à 2 cm (durée médiane de suivi : 11,9 mois), cet essai évalue l'efficacité, du point de vue du contrôle local de la maladie, d'une résection neurochirurgicale en combinaison avec une curithérapie intra-opératoire par grains de césium-131
Background : Studies on adjuvant stereotactic radiosurgery (SRS) to the cavity of resected brain metastases suggest that larger tumors (>2.0 cm) have higher rates of recurrence and radionecrosis (RN). This study assesses the impact of permanent low-dose 131Cs brachytherapy on local control and RN in patients treated for large brain metastases. Methods : After IRB approval, 42 patients with a total of 46 metastases >2.0 cm in preoperative diameter were accrued onto a prospective trial between 2010 and 2015. Patients underwent surgical resection with intra-operative placement of stranded 131Cs seeds as permanent volume implants in the resection cavity. The primary endpoint was local freedom from progression (FFP). Secondary endpoints included regional and distant FFP, overall survival (OS), and RN rate. Failures between 5 mm and 20 mm from the cavity, as well as dural-based failures, were considered regional. Separate analysis was performed for metastases > 3.0 cm. Results : Of the 46 metastases, 18 were > 3.0 cm in diameter. The median follow-up period was 11.9 months (range, 0.6 – 51.9 months). Metastases had a median preoperative diameter of 3.0 cm (range, 2.0 – 6.8 cm). Local FFP was 100% for all tumor sizes. Regional recurrences were found in 3/46 (7%) lesions, yielding a 1-year region FFP of 89% (for tumors > 3.0 cm this was 80% (95% CI 54%, 100%). Distant recurrences were found in 19/46 (41%) patients yielding a 1-year distant FFP of 52%. The median OS was 15.1 months with a 1-year OS of 58%. Lesion size was not significantly associated with any endpoint in univariate or multivariate analysis. Radioresistant histology had worse survival (p=0.036). There were no cases of RN. Conclusion : Intraoperative 131Cs brachytherapy is a promising and effective therapy for large brain metastases requiring neurosurgical intervention, which may offer improved local control and lower rates of RN compared with SRS to the resection cavity.