Long‐term outcomes of skull base chordoma treated with high‐dose carbon‐ion radiotherapy

Abstract

Background We evaluated the long‐term efficacy and safety of carbon‐ion radiotherapy (C‐ion RT) for skull base chordoma, a rare neoplasm. Methods Thirty‐four patients with skull base chordoma who were treated with C‐ion RT were prospectively enrolled and analyzed retrospectively. C‐ion RT was delivered with 60.8 Gy (relative biological effectiveness [RBE]) in 16 fractions at four fractions per week. Results The median follow‐up period was 108 months. The 5‐ and 9‐year local control rates were 76.9% and 69.2%, respectively. The 5‐ and 9‐year overall survival rates were 93.5% and 77.4%, respectively. Regarding grade 3 or more severe late reactions, one patient developed a grade 3 mucosal ulcer, two developed grade 4 ipsilateral optic nerve injuries, and one developed a grade 5 mucosal ulcer at 9 years and 3 months after C‐ion RT. Conclusion C‐ion RT with 60.8 Gy (RBE)/16 fractions is a promising treatment option for inoperable skull base chordoma.

Brainstem NTCP and Dose Constraints for Carbon Ion RT—Application and Translation From Japanese to European RBE-Weighted Dose

“…The estimated 5-year local control (LC) rate was 71%. This is inferior to the results reported by Japanese centers, where 5-year LC rates within the range 76–92% have been reported ( 20 , 21 ).…”

“… Absolute volume DVH showing old CNAO D LEM I|1% <30 Gy (RBE) constraint (cross) and the translated Shirai constraints D LEM I|0.7 cm 3 <41 Gy (RBE) and D LEM I|0.1 cm 3 <49 Gy (RBE) (squares, error bars = 95% CI), converted into EQD2 (assuming α/β ratio = 2 Gy) in comparison with the EQD2 constraints applied at HIT as reported by Nikoghosyan et al. ( 21 ): D LEM I|1% <54 Gy (RBE) and D LEM I|max <60 Gy (RBE) (circles). As an approximation to the absolute volume relating to the D 1% constraints, the median brainstem volume in our data set (26 cm 3 ) was used.…”

Carbon Ion Dose Constraints in the Head and Neck and Skull Base: Review of MedAustron Institutional Protocols

“…The CIRT has been used to treat several tumors of the head and neck area. It has not been employed for squamocellular carcinoma-the most common entity-but rather, for other, radioresistant histologies, such as salivary gland tumors [15][16][17][18][19][20][21][22], paranasal sinuses tumors (including sinonasal undifferentiated carcinoma, sinonasal adenocarcinoma, intestinal-type adenocarcinoma, and esthesioneuroblastoma, among others) [15,23], mucosal melanoma [24][25][26][27][28], lacrimal gland tumors [29][30][31], and bone and soft tissue sarcoma (including tumors of the skull base and cervical spine [32][33][34][35][36][37][38] At MedAustron, CIRT was begun in July 2019. Until September 2020, 91 patients have been treated and 42 of them had tumors in the head and neck.…”

A Review of Particle Therapy for Skull Base Tumors: Modern Considerations and Future Directions

“…As outlined earlier, medium-size chordomas with unfavorable geometry and large-volume unresectable tumors have lower control rates; thus, given the encouraging reports from National Institute of Radiological Sciences [ 37 ], we would apply carbon ion therapy in a prospective setting. At present, it is not possible, by analyzing these retrospective data, to conclude anything about the relative merits of protons and carbon ions.…”

“…In the large majority of particle therapy series, gross tumor volume correlated with local control, and patients with small residual disease had a better outcome [ 22 , 24 , 26 – 29 , 36 , 37 ]. Moreover, several series demonstrated a correlation between compression of brainstem and/or optic pathways and outcome [ 26 , 29 , 34 ].…”