Outcomes of Patients with Primary Sacral Chordoma Treated with Definitive Proton Beam Therapy
Menée au Japon à partir de données portant sur 33 patients atteints d'un chordome primitif du sacrum (durée médiane de suivi : 37 mois), cette étude évalue l'efficacité, du point de vue des taux de survie à 3 ans, et la toxicité d'une protonthérapie définitive
Purpose : To evaluate the efficacy and safety of definitive proton beam therapy (PBT) for primary sacral chordoma. Methods and Materials : We conducted a retrospective analysis of the clinical outcomes of eligible patients with primary sacral chordoma who underwent definitive PBT with 70.4 Gy (relative biological effectiveness) in 32 fractions at our institution between September 2009 and October 2015. Local progression-free survival, distant metastasis-free survival, disease-free survival, cause-specific survival, and overall survival were evaluated. To explore the factors that influenced local progression, the following parameters were analyzed: sex, the presence of a spacer (GORE-TEX sheets), gross tumor volume (mL), and the extent of cranial tumor extension. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events, version 4.0. To assess the impact of PBT on pain relief, the change in pain grades was investigated between the initiation of PBT and the last follow-up. Results : Thirty-three eligible patients were analyzed. The median follow-up period was 37 months. The 3-year estimated local progression-free survival, distant metastasis-free survival, disease-free survival, cause-specific survival, and overall survival rates were 89.6%, 88.2%, 81.9%, 95.7%, and 92.7%, respectively. There was no significant association between the patients’ clinicopathological characteristics and local progression-free survival. Four patients developed Grade 3 adverse events, including acute dermatitis (n = 1), ileus (n = 1), and pain due to sacral insufficiency fractures (n = 2). The pain grades were improved, unchanged, or deteriorated in 15, 7, and 11 patients, respectively. Conclusions : Definitive PBT with 70.4 Gy (relative biological effectiveness) in 32 fractions is an effective treatment with acceptable toxicity for primary sacral chordoma, and has the potential to reduce pain.