A single-center experience of the upright proton therapy for skull-base chordomas and chondrosarcomas: Updated results

• Published in: Clinical and translational radiation oncology 2024-09, Vol.48, p.100814, Article 100814
• Main Authors: Lemaeva, Alyona, Gulidov, Igor, Smyk, Daniil, Agapova, Yuliya, Koryakin, Sergey, Eremina, Irina, Gantsova, Elena, Fatkhudinov, Timur, Kaprin, Andrey, Gordon, Konstantin
• Format: Article
• Language: English
• Subjects: Chondrosarcoma; Chordoma; Original; Proton therapy; Radiation therapy; Skull base; Upright position
• ISSN: 2405-6308; 2405-6308
• DOI: 10.1016/j.ctro.2024.100814

•Upright proton therapy shows both safety and effectiveness for complex cases of the skull base chordomas and chondrosarcomas.•Low 95%-dose coverage and brain stem involvement remain the leading reasons for treatment failure. To access efficacy and safety of the upright proton therapy for the skull-base chordomas and chondrosarcomas. The study encompasses single-center experience of proton therapy in chordomas (CA) and chondrosarcomas (CSA) of skull-base localization. We evaluate overall survival, local control and toxicity. Tumor response was assessed in accordance with RANO criteria. Treatment-related toxicity was evaluated with the help of CTCAE v 5.0 scale. Proton therapy in the upright position was utilized for 51pts (patients) with CA-CSA (40 pts with chordoma and 11pts with chondrosarcoma) at the A. Tsyb Medical Radiological Research Center in 2016–2023. Median tumor volume constituted 30 cm3 (IQR (interquartile range) 15–41 cm3). Median total dose was 70 GyRBE. Median number of fractions was 35. Overall survival (OS) at 1-, 2- and 3-year rates reached 98.0 %, 88.6 % and 82.7 %, respectively. Median follow-up time was 36 months. The 1-, 2- and 3-year local control (LC) rates constituted, respectively, 98 %, 78.6 % and 66.3 %. Prior surgery showed statistically significant association with better prognosis (p = 0.023). Brainstem-to-tumor dose coverage compromise became the major pattern of LC failure (p = 0.03). The late radiation toxicity reactions included temporal lobe necrosis grade 2 in 2 pts, xerostomia grade 1 in 1pt, radiation cataract grade 2 in 1pt and persistent headache grade 2 in 4 pts. Severe late toxicity reactions were observed in 2 cases (4 %): 1 myelitis grade 3 and brainstem damage grade 5 in 1pt. Local control was achieved in the majority of patients receiving the scanning-beam upright proton therapy for skull-base CA-CSA. The LC rates after a surgery-radiotherapy combination treatment were higher compared with irradiation alone. Pattern of failure is mostly brainstem-tumor dose compromise. The high OS and LC rates were accompanied by low toxicity incidence. Even in complex case of the skull base CA-CSA upright proton therapy shows promising clinical outcomes.