RT Journal Article SR Electronic T1 Unresectable Chondrosarcomas Treated With Carbon Ion Radiotherapy: Relationship Between Dose-averaged Linear Energy Transfer and Local Recurrence JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 6429 OP 6435 DO 10.21873/anticanres.14664 VO 40 IS 11 A1 SHINNOSUKE MATSUMOTO A1 SUNG HYUN LEE A1 REIKO IMAI A1 TAKU INANIWA A1 NARUHIRO MATSUFUJI A1 MAI FUKAHORI A1 RYOSUKE KOHNO A1 SHUNSUKE YONAI A1 NORIYUKI OKONOGI A1 SHIGERU YAMADA A1 NOBUYUKI KANEMATSU YR 2020 UL http://ar.iiarjournals.org/content/40/11/6429.abstract AB Background/Aim: The local control rate of chondrosarcomas treated with carbon-ion radiotherapy (CIRT) worsens as tumour size increases, possibly because of the intra-tumoural linear energy transfer (LET) distribution. This study aimed to evaluate the relationship between local recurrence and intra-tumoural LET distribution in chondrosarcomas treated with CIRT. Patients and Methods: Thirty patients treated with CIRT for grade 2 chondrosarcoma were included. Dose-averaged LET (LETd) distribution was calculated by the treatment planning system, and the relationship between LETd distribution in the planning tumour volume (PTV) and local control was evaluated. Results: The mean LETd value in PTV was similar between cases with and without recurrence. Recurrence was not observed in cases where the effective minimum LETd value exceeded 40 keV/μm. Conclusion: LETd distribution in PTV is associated with local control in chondrosarcomas and patients treated with ion beams of higher LETd may have an improved local control rate for unresectable chondrosarcomas.