Sonja Stieb1, James W Snider2, Lorenzo Placidi3, Ulrike Kliebsch3, Anthony J Lomax4, Ralf A Schneider3, Damien C Weber5. 1. Center for Proton Therapy, Paul Scherrer Institute, ETH Domain, Villigen, Switzerland; Radiation Oncology Department, University Hospital of Bern, Bern, Switzerland. 2. Center for Proton Therapy, Paul Scherrer Institute, ETH Domain, Villigen, Switzerland; Department of Radiation Oncology, University of Maryland Medical Center, Baltimore, Maryland. 3. Center for Proton Therapy, Paul Scherrer Institute, ETH Domain, Villigen, Switzerland. 4. Center for Proton Therapy, Paul Scherrer Institute, ETH Domain, Villigen, Switzerland; Department of Physics, ETH Zurich, Zurich, Switzerland. 5. Center for Proton Therapy, Paul Scherrer Institute, ETH Domain, Villigen, Switzerland; Radiation Oncology Department, University Hospital of Bern, Bern, Switzerland; Radiation Oncology Department, University Hospital of Zürich, University of Zürich, Zürich, Switzerland. Electronic address: damien.weber@psi.ch.
Abstract
PURPOSE: To assess the radiation dose tolerance of the spinal cord by reviewing our institutional experience regarding the incidence of radiation-induced spinal cord toxicity after high-dose pencil beam scanning proton therapy (PBSPT). METHODS AND MATERIALS: Seventy-six patients (median age 53 years; range, 23-79 years) treated for spinal chordoma (n=55) or chondrosarcoma (n=21) met the following criteria and were retrospectively analyzed: PBSPT only, no reirradiation or concomitant chemotherapy, maximum dose (Dmax) to the spinal cord of ≥45 Gy(relative biological effectiveness [RBE]), ≥18 years of age, and follow-up of ≥12 months. The delivered dose was 59.4 to 75.2 Gy(RBE) [median 73.9 Gy(RBE)] delivered with conventional fractionation between 2000 and 2014. The Dmax, D2%, and V40-V60 of the surface (sSC) and center (cSC) of the spinal cord were recorded. Toxicity was scored according to the Common Terminology Criteria for Adverse Events, version 4.03. RESULTS: Median follow-up was 65.5 months (range, 13-173 months). Patients received a mean Dmax and D2% to the sSC of 59.0 (median 58.7; range, 48.3-75.9) and 55.3 (median 52.7; range, 43.1-73.8) Gy(RBE), respectively. The corresponding values for the cSC were 52.3 (median 52.7; range, 32.3-73.3) and 51.1 (median 52.0; range, 25.3-73.1) Gy(RBE), respectively. Four patients (5%) developed acute radiation-induced neurotoxicity (grade [G] 1, n=1; G2, n=3). Twelve patients (16%) experienced late neurologic toxicities (G1, n=7; G2, n=4; G4, n=1). One patient with a history of pre-PBSPT symptomatic spinal cord compression redeveloped tetraplegia (G4) after receiving a Dmax of 57.8 Gy(RBE) to the sSC and 54.1 Gy(RBE) to the cSC. No significant correlation was found between sSC Dmax and D2%, cSC Dmax and D2%, or the length of CTV and toxicity. CONCLUSIONS: High-dose conformal PBSPT may be delivered safely in close proximity to the spinal cord with minimal neurotoxicity. Dose constraints of 64 Gy(RBE) as D2% for the sSC and 54 Gy(RBE) for the cSC seem appropriate for clinical use.
PURPOSE: To assess the radiation dose tolerance of the spinal cord by reviewing our institutional experience regarding the incidence of radiation-induced spinal cord toxicity after high-dose pencil beam scanning proton therapy (PBSPT). METHODS AND MATERIALS: Seventy-six patients (median age 53 years; range, 23-79 years) treated for spinal chordoma (n=55) or chondrosarcoma (n=21) met the following criteria and were retrospectively analyzed: PBSPT only, no reirradiation or concomitant chemotherapy, maximum dose (Dmax) to the spinal cord of ≥45 Gy(relative biological effectiveness [RBE]), ≥18 years of age, and follow-up of ≥12 months. The delivered dose was 59.4 to 75.2 Gy(RBE) [median 73.9 Gy(RBE)] delivered with conventional fractionation between 2000 and 2014. The Dmax, D2%, and V40-V60 of the surface (sSC) and center (cSC) of the spinal cord were recorded. Toxicity was scored according to the Common Terminology Criteria for Adverse Events, version 4.03. RESULTS: Median follow-up was 65.5 months (range, 13-173 months). Patients received a mean Dmax and D2% to the sSC of 59.0 (median 58.7; range, 48.3-75.9) and 55.3 (median 52.7; range, 43.1-73.8) Gy(RBE), respectively. The corresponding values for the cSC were 52.3 (median 52.7; range, 32.3-73.3) and 51.1 (median 52.0; range, 25.3-73.1) Gy(RBE), respectively. Four patients (5%) developed acute radiation-induced neurotoxicity (grade [G] 1, n=1; G2, n=3). Twelve patients (16%) experienced late neurologic toxicities (G1, n=7; G2, n=4; G4, n=1). One patient with a history of pre-PBSPT symptomatic spinal cord compression redeveloped tetraplegia (G4) after receiving a Dmax of 57.8 Gy(RBE) to the sSC and 54.1 Gy(RBE) to the cSC. No significant correlation was found between sSC Dmax and D2%, cSC Dmax and D2%, or the length of CTV and toxicity. CONCLUSIONS: High-dose conformal PBSPT may be delivered safely in close proximity to the spinal cord with minimal neurotoxicity. Dose constraints of 64 Gy(RBE) as D2% for the sSC and 54 Gy(RBE) for the cSC seem appropriate for clinical use.
Authors: Sara Rosas; Francesca M Belosi; Nicola Bizzocchi; Till Böhlen; Stefan Zepter; Petra Morach; Antony J Lomax; Damien C Weber; Jan Hrbacek Journal: Br J Radiol Date: 2020-01-30 Impact factor: 3.039
Authors: Sang Hee Youn; Kwan Ho Cho; Joo-Young Kim; Boram Ha; Young Kyung Lim; Jong Hwi Jeong; Sang Hyun Lee; Heon Yoo; Ho-Shin Gwak; Sang Hoon Shin; Eun Kyung Hong; Han Kyu Kim; Je Beom Hong Journal: Radiat Oncol J Date: 2018-09-30