Proton stereotactic radiosurgery for brain metastases: a single institution analysis of 370 patients
Menée à partir de données portant sur 370 patients présentant une ou plusieurs métastases cérébrales traitées entre 1991 et 2016 (durée médiane de suivi après traitement : 9,2 mois), cette étude évalue l'intérêt, du point de vue de la tolérabilité et du contrôle local, d'une radiochirurgie stéréotaxique par faisceaux de protons
Background : Proton stereotactic radiosurgery (SRS) has been well-characterized for treatment of benign intracranial neoplasms. However, there is a paucity of data on its use for treatment of malignant intracranial disease, which was studied herein. Methods : Single institution, retrospective study of 815 metastases from 370 patients treated with proton SRS between April 1991 and November 2016. Cumulative incidence estimates of local failure, distant brain failure, and pathologically-confirmed radionecrosis and Kaplan-Meier estimates of overall survival were calculated. Fine and Gray and Cox regressions were performed to ascertain whether clinical and treatment factors were associated with the described endpoints. Results : The median follow-up from proton SRS was 9.2 months. The 6- and 12-month estimates of local failure, distant brain failure, and overall survival were 4.3% (95% CI, 3.0–5.9%) and 8.5% (95% CI, 6.7–10.6%), 39.1% (95% CI, 34.1–44.0%) and 48.2% (95% CI, 43.0–53.2%), and 76.0% (95% CI, 71.3–80.0%) and 51.5% (95% CI, 46.3–56.5%), respectively. The median survival was 12.4 months (95% CI, 10.8–14.0 months) following proton SRS. The most common symptoms were low-grade fatigue (12.5%), headache (10.0%), motor weakness (6.2%), seizure (5.8%), and dizziness (5.4%). The rate of pathologically-confirmed radionecrosis at 12 months was 3.6% (95% CI, 2.0–5.8%) and only target volume was associated on multivariate analysis (subdistribution hazard ratio, SHR [1.13] 95% CI, 1.0–1.20). Conclusions : To the best of our knowledge, this is the first reported series of proton SRS for the management of brain metastases. Moderate dose proton SRS is well-tolerated and can achieve good local control outcomes, comparable to those obtained with conventional photon SRS strategies. While proton SRS remains resource-intensive, future strategies evaluating its selective utility in patients whom would benefit most from integral dose reduction should be explored.