A dose response analysis of injury to cranial nerves and/or nuclei following proton beam radiation therapy

“…), with a dose-response curve slope at 50% of 3.2 (2.2 to 5.4, 95% C.L.) [43]. Doses to brain stem, optic nerves and chiasm, and auditory nerves and cochlea are constrained as noted above; dose constraints are not employed for the other cranial nerves.…”

Section: Brain Stem and Cervical Spinalmentioning

confidence: 99%

Proton therapy for tumors of the skull base

1999

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Charged particle beams are ideal for treating skull base and cervical spine tumors: dose can be focused in the target, while achieving significant sparing of the brain, brain stem, cervical cord, and optic nerves and chiasm. For skull base tumors, 10-year local control rates with combined proton-photon therapy are highest for chondrosarcomas, intermediate for male chordomas, and lowest for female chordomas (94%, 65%, and 42%, respectively). For cervical spine tumors, 10-year local control rates are not significantly different for chordomas and chondrosarcomas (54% and 48%, respectively), nor is there any difference in local control between males and females. Observed treatment-related morbidity has been judged acceptable, in view of the major morbidity and mortality which accompany uncontrolled tumor growth.

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“…Urie et al (33) performed a very detailed analysis of the normal anatomy, dose distribution, and clinical outcomes of 27 patients treated with protons for skull base tumors, and found 5 patients with neurological symptoms that were attributed to radiation injury. They analyzed 594 CNS structures (22 structures per patient in 27 patients), and found 17 structures with clinically manifest radiation injury and concluded that "for dose fractionation of 1.8 -2.0 CGE, the probability of radiation injury is 5% at 70 CGE (64 -81 CGE with 95% confidence).…”

Section: Discussionmentioning

confidence: 99%

Temporal Lobe (TL) Damage Following Surgery and High-Dose Photon and Proton Irradiation in 96 Patients Affected by Chordomas and Chondrosarcomas of the Base of the Skull

Santoni

Liebsch

Finkelstein

et al. 1998

International Journal of Radiation OncologyBiologyPhysics

102

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Purpose: To determine the temporal lobe (TL) damage rate in 96 patients treated with high-dose proton and photon irradiation for chordomas and chondrosarcomas of the base of the skull. Methods and Materials: The records of 96 consecutive patients treated at Massachusetts General Hospital (MGH) and Harvard Cyclotron Laboratory (HCL) between June 1984 and 1993, for chordomas and chondrosarcomas of the base of the skull were reviewed. All the patients had undergone some degree of resection of the tumor prior to radiation therapy. Seventy-five patients were classified as "primary tumors" and 21 as recurrent or regrowing tumors after one or more surgical procedures. All the patients were randomized to receive 66.6 or 72 cobalt Gray equivalent (CGE) on a prospective dose-searching study by proton and photon irradiation (Radiation Therapy Oncology Group #85-26) with conventional fractionation (1.8 CGE/day, 5 fractions/week). All treatments were planned using the three-dimensional (3D) planning system developed at the Massachusetts General Hospital, and the dose was delivered using opposed lateral fields for the photon component and a noncoplanar isocentric technique for the proton component. Clinical symptoms of TL damage were classified into 4 grades. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans were evaluated for white matter changes. Abnormalities associated with persistent or recurrent tumor were distinguished from radiation-induced changes. TLs were delineated on the original scans of the 10 patients with damage and those of a group of 33 patients with no clinical or MRI evidence of injury. Dose distributions were calculated and dose-volume histograms were obtained for these patients. Results: Of the patients, 10 developed TL damage, with bilateral injury in 2 and unilateral injury in 8. The cumulative TL damage incidence at 2 and 5 years was 7.6 and 13.2%, respectively. The MRI areas suggestive of TL damage were always separated from the tumor bed. Symptoms were severe to moderate in 8 patients. Several baseline factors, tumor-or host-related, were analyzed to evaluate their predictivity for TL damage: age, gender, tumor site, histology, type of presentation, type and number of surgical procedures, primary tumor volume, prescribed dose, normal tissue involvement, and volume of TL receiving doses ranging between 10 and 50 CGE or more. Only gender, in a univariate analysis (log rank) was a significant predictor of damage (0.0155), with male patients being at significantly higher risk of TL injury. In a stepwise Cox regression that included gender as a variable, no other baseline variable improved the prediction of damage. Conclusions: The 2-and 5-year cumulative TL damage rates were 7.6 and 13.2%, respectively. Despite the different TL damage rates related to age, tumor volume, number of surgical procedures prior to radiation therapy, and prescribed doses to the tumor, only gender was a significant predictor of damage (p ‫؍‬ 0.0155) using a univariate (log rank) test. Chordomas and chondr...

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A dose response analysis of injury to cranial nerves and/or nuclei following proton beam radiation therapy

Cited by 88 publications

References 39 publications

Effectiveness and Safety of Spot Scanning Proton Radiation Therapy for Chordomas and Chondrosarcomas of the Skull Base: First Long-Term Report

Effectiveness and Safety of Spot Scanning Proton Radiation Therapy for Chordomas and Chondrosarcomas of the Skull Base: First Long-Term Report

Proton therapy for tumors of the skull base

Temporal Lobe (TL) Damage Following Surgery and High-Dose Photon and Proton Irradiation in 96 Patients Affected by Chordomas and Chondrosarcomas of the Base of the Skull

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