Purpose

1. Minimal Acute Toxicities Following High-Dose Proton Therapy for Spinal Tumors Jennifer Jefferis, RN1; William Hartsell, MD1; John Chang, MD1; Vinai Gondi, MD1,2 1CDH Proton Center, Warrenville, IL; 2Cadence Brain Tumor Center, Warrenville, IL Figure 1. 63 year old M p/w grade I myxopapillaryependymoma from T9 to sacral nerve roots, status post biopsy. Treated with postop proton beam therapy from T9-sacral nerve roots to 45 CGyE, followed by sequential boost from below the spinal cord termination to sacral nerve roots for cumulative dose of 59.4 CGyE. Two oblique posterior proton beams were utilized, with distal range positioned in the middle of the vertebral body. With zero dose delivered to the anterior visceral compartment, the patient reported no toxicities, except for grade 1 erythema. • Using posterior proton beams and positioning distal range anterior to spinal target volume limits dose to anterior visceral structures, including esophagus, stomach, bowel and bladder • Objective: Assess whether this dosimetric advantage of proton therapy impacts clinical outcomes in terms of acute toxicities in patients treated to >50 CGyE. Purpose Materials and Methods • Patients treated to >50 CGyE for spinal tumors at a single proton center, consecutively enrolled on the PCG Registry • Exclusion criteria: concurrent cranial irradiation or chemotherapy prior or during treatment • Treated in supine or prone Position • Treatments were delivered at 1.8 CGyE/Fraction • Weekly physician evaluations with physician-assessed toxicities graded using CTCAE v4.0 59.4 0.01 Dose Scale Table 1. Acute Toxicities Results 19 patients received proton therapy for spinal tumors. Median age was 49 (range 12-74). 5 patients had chordoma/chondrosarcoma (dose range 70.4-75.8 CGyE); 1 patient had sarcoma (66.3 CGyE); 5 patients had a WHO grade II ependymoma (54.2-59.6 CGyE); 4 patients had a WHO grade I myxopapillaryependymoma (52.3-59.6 CGyE); 3 patients had benign or malignant peripheral nerve sheath tumor (57.9-59.8 CGyE); and, 1 patient had hemangioma (50.5 CGyE). 16 patients developed grade 1 dermatitis. Grade 2 desquamation was observed in 2 patients (11%) treated to 72 CGyE, and grade 3 desquamation was observed in 1 patient (5%), treated to 75.8 CGyE. Aside from desquamation, no grade ≥2 acute toxicities were observed. 2 patients (11%) treated to ≥72 CGyE, developed grade 1 diarrhea. 2 patients (11%) treated to ≥72 CGyE developed grade 1 urinary frequency. 2 patients (11%) reported grade 1 fatigue. Conclusion Proton therapy to >50 CGyE for spinal tumors is well tolerated, with no grade ≥2 non-dermatologic acute toxicities and grade 1 acute GI and GU toxicities only in patients treated to ≥72 CGyE. Dermatologic toxicities were observed in all patients, but severe only in patients treated to ≥72 CGyE.