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The Role of Proton Radiation Therapy in Central Neurocytoma
Volume 99 Number 2S Supplement 2017 recurrence with a decrease of recurrence by 7% per Gy (RBE) (pZ0.04). Median time to failure was 2 years (range 0.4-5.3). Two-year local recurrence rate was 10.6%. Median proton dose delivered was 54 Gy (RBE) (range 18-59.4) and 4 patients (19%) received concurrent temozolomide. There were 9 deaths among those who failed (43%) with a median time to death of 3.9 years and an 8.6 higher risk of death compared to patients without a recurrence (pZ0.001). Conclusion: Of those lower grade glioma patients who had documented failures after proton radiation therapy, 60% recurred within the radiation field. Further analysis of the relationship between failure patterns and proton dosimetry is ongoing. Author Disclosure: S.C. Kamran: None. M.L. Dworkin: None. A. Niemierko: None. K.S. Oh: Research Grant; Elekta, Merck & Co., Inc.. Review and create questions for CME section of journal; IJROBP. J.S. Loeffler: None. H.A. Shih: Employee; Dartmouth Hitchcock. Honoraria; International Journal of Radiation Oncology, UpToDate. Advisory Board; Genentech. clinical operarions director; MGH Proton Therapy Center. clinical operational leader; Massachusetts General Hospital. editor; International Journal of Radiation Oncology. hospital site residency program director; Harv.
2195 The Role of Proton Radiation Therapy in Central Neurocytoma K.H. Kang,1 E. Schapira,2 A. Niemierko,2 and H.A. Shih2; 1Case Western Reserve University School of Medicine, Cleveland, OH, 2Massachusetts General Hospital, Boston, MA Purpose/Objective(s): Central neurocytomas (CN) are rare, well-differentiated WHO grade II tumors of neuronal or neuroglial origin typically managed with surgery and possible adjuvant radiation therapy (RT). We investigated the outcomes of affected patients treated with surgery and/or proton beam therapy (PBT) to explore the optimal timing and efficacy of PBT. Materials/Methods: This retrospective, single-institution study includes patients diagnosed and treated for CN between 1996-2016. We identified 63 cases, of which 32 met the inclusion criteria. Patient, tumor, and treatment characteristics were collected and evaluated in context of treatment complications (CTCAE v.4) and tumor progression-free survival. Univariable survival analysis was performed using the Kaplan-Meier technique with log-rank test. Univariable Cox proportional hazards model was used to analyze variables associated with recurrence. Fisher’s exact test was used to test for association between categorical variables. Results: The median age at diagnosis was 21 years. Our cohort was 66% female. Common presenting symptoms were headache (72%), nausea/vomiting (34%), and visual changes (28%). Median tumor diameter was 4.3 cm (1.4-6.8), and median MIB-1 index was 4% (130). 50% (16/32) of patients underwent resection alone. The majority (72%) of resections were subtotal. Half of the patients received PBT as either adjuvant therapy or for disease recurrence at a median dose of 51.3 Gy(RBE) (36-54). Two patients received adjuvant chemotherapy in addition to adjuvant PBT. The median follow-up was 49.8 months (3.5-233.7). The 3- and 5-year local control rates for surgery-only patients were 61.8% and 49.4%, respectively. Median time to local recurrence was 34 months (3.5-233.7). MIB-1 >4.5% was associated with worse local recurrence-free survival (pZ0.0372). MIB-1 >4.5% was associated with surgery-only patients who experienced local failure (p<0.001); they had a 1- and 2-year local failure rate of 67% and 17%, respectively. There were no local failures for patients treated with PBT definitively or for recurrence at a median follow-up time of 29 months. The most common adverse events related to PBT were fatigue, alopecia, nausea, radiation dermatitis, and concentration impairment, with 23.7% (9/38) reported grade 2 toxicities; there were no grade 3+
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toxicities. The most common toxicities following surgery were memory impairment, hemiplegia, seizures, dizziness, and dysphasia. There were 40% (18/45) grade 2 and 11% (5/45) grade 3+ toxicities. Grade 3 toxicities were dysphagia, aphonia, and hydrocephalus, and there was one grade 4 toxicity (papilledema). Conclusion: Our findings suggest that for patients with an elevated MIB-1 index, maximal safe surgery followed by adjuvant proton beam therapy may offer the best balance of long-term local control with minimization of toxicity. Future directions include a larger cohort in a prospective, multiinstitution study. Author Disclosure: K.H. Kang: None. E. Schapira: None. A. Niemierko: None. H.A. Shih: Employee; Dartmouth Hitchcock. Honoraria; International Journal of Radiation Oncology, UpToDate. Advisory Board; Genentech. clinical operarions director; MGH Proton Therapy Center. clinical operational leader; Massachusetts General Hospital. editor; International Journal of Radiation Oncology. hospital site residency program director; Harv.
2196 Radiosurgery for Brain Metastases: Practice Patterns and Disparities in the United States B.H. Kann,1 H.S.M. Park,2 V.L. Chiang,3 and J.B. Yu2; 1Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, 2Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, 3Department of Neurosurgery, Yale University School of Medicine, New Haven, CT Purpose/Objective(s): Up to 20% of patients diagnosed with cancer will develop brain metastases. Management typically includes radiotherapy with conventional fractionation (CFRT), generally to the whole brain, and/ or stereotactic radiosurgery (SRS). Studies over the past decade have demonstrated the efficacy of SRS for a limited number of brain metastases, though controversy remains regarding appropriateness, patient selection, and timing of SRS use. The uptake of SRS use in the United States during this period has not been evaluated. We evaluated national practice patterns for patients with metastatic disease receiving radiotherapy to the brain. Materials/Methods: We queried the National Cancer Data Base for patients diagnosed with metastatic non-small cell lung cancer (NSCLC), breast cancer, melanoma, and colorectal cancer from 2004 to 2014 who received upfront radiotherapy to the brain with available dose information. Patients who received documented SRS or radiation with dose per fraction 6 Gy were assigned to the SRS cohort, and all others were assigned to the CFRT cohort. Patient- and hospitallevel predictors of SRS use were analyzed with univariable chisquare tests and multivariable mixed-effects logistic regression. All statistical tests were two-sided and P < .05 was statistically significant. Results: Of 75,962 patients treated among 1,215 facilities, 12,332 (16.2%) received SRS and 63,630 (83.8%) received CFRT. The proportion of patients receiving upfront SRS increased yearly, from 9.9% of patients in 2004 to 25.6% in 2014 (P < .001). The number of facilities using SRS also increased yearly from 264 (21.7%) in 2004 to 542 (44.6%) in 2014. SRS was utilized least among breast cancer patients (12.1%) and most among melanoma patients (26.9%). On multivariable analysis, predictors of CFRT use included Black or Hispanic race/ ethnicity (OR: 1.27, 95%CI: 1.07 e 1.50), non-private insurance (OR: 1.20, 95%CI: 1.14 e 1.27), lower income (OR: 1.19, 95%CI: 1.12 e 1.26), non-academic facility (OR: 2.02, 95%CI: 1.73 e 2.37), and nonmetropolitan area (OR: 1.12, 95%CI: 1.03 e 1.21). SRS use increased disproportionally among higher-income and privately insured patients during the study period. Conclusion: This national study demonstrates a steady increase in SRS utilization for patients with brain metastases over the past decade. The
2195 The Role of Proton Radiation Therapy in Central Neurocytoma K.H. Kang,1 E. Schapira,2 A. Niemierko,2 and H.A. Shih2; 1Case Western Reserve University School of Medicine, Cleveland, OH, 2Massachusetts General Hospital, Boston, MA Purpose/Objective(s): Central neurocytomas (CN) are rare, well-differentiated WHO grade II tumors of neuronal or neuroglial origin typically managed with surgery and possible adjuvant radiation therapy (RT). We investigated the outcomes of affected patients treated with surgery and/or proton beam therapy (PBT) to explore the optimal timing and efficacy of PBT. Materials/Methods: This retrospective, single-institution study includes patients diagnosed and treated for CN between 1996-2016. We identified 63 cases, of which 32 met the inclusion criteria. Patient, tumor, and treatment characteristics were collected and evaluated in context of treatment complications (CTCAE v.4) and tumor progression-free survival. Univariable survival analysis was performed using the Kaplan-Meier technique with log-rank test. Univariable Cox proportional hazards model was used to analyze variables associated with recurrence. Fisher’s exact test was used to test for association between categorical variables. Results: The median age at diagnosis was 21 years. Our cohort was 66% female. Common presenting symptoms were headache (72%), nausea/vomiting (34%), and visual changes (28%). Median tumor diameter was 4.3 cm (1.4-6.8), and median MIB-1 index was 4% (130). 50% (16/32) of patients underwent resection alone. The majority (72%) of resections were subtotal. Half of the patients received PBT as either adjuvant therapy or for disease recurrence at a median dose of 51.3 Gy(RBE) (36-54). Two patients received adjuvant chemotherapy in addition to adjuvant PBT. The median follow-up was 49.8 months (3.5-233.7). The 3- and 5-year local control rates for surgery-only patients were 61.8% and 49.4%, respectively. Median time to local recurrence was 34 months (3.5-233.7). MIB-1 >4.5% was associated with worse local recurrence-free survival (pZ0.0372). MIB-1 >4.5% was associated with surgery-only patients who experienced local failure (p<0.001); they had a 1- and 2-year local failure rate of 67% and 17%, respectively. There were no local failures for patients treated with PBT definitively or for recurrence at a median follow-up time of 29 months. The most common adverse events related to PBT were fatigue, alopecia, nausea, radiation dermatitis, and concentration impairment, with 23.7% (9/38) reported grade 2 toxicities; there were no grade 3+
Poster Viewing
E83
toxicities. The most common toxicities following surgery were memory impairment, hemiplegia, seizures, dizziness, and dysphasia. There were 40% (18/45) grade 2 and 11% (5/45) grade 3+ toxicities. Grade 3 toxicities were dysphagia, aphonia, and hydrocephalus, and there was one grade 4 toxicity (papilledema). Conclusion: Our findings suggest that for patients with an elevated MIB-1 index, maximal safe surgery followed by adjuvant proton beam therapy may offer the best balance of long-term local control with minimization of toxicity. Future directions include a larger cohort in a prospective, multiinstitution study. Author Disclosure: K.H. Kang: None. E. Schapira: None. A. Niemierko: None. H.A. Shih: Employee; Dartmouth Hitchcock. Honoraria; International Journal of Radiation Oncology, UpToDate. Advisory Board; Genentech. clinical operarions director; MGH Proton Therapy Center. clinical operational leader; Massachusetts General Hospital. editor; International Journal of Radiation Oncology. hospital site residency program director; Harv.
2196 Radiosurgery for Brain Metastases: Practice Patterns and Disparities in the United States B.H. Kann,1 H.S.M. Park,2 V.L. Chiang,3 and J.B. Yu2; 1Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, 2Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, 3Department of Neurosurgery, Yale University School of Medicine, New Haven, CT Purpose/Objective(s): Up to 20% of patients diagnosed with cancer will develop brain metastases. Management typically includes radiotherapy with conventional fractionation (CFRT), generally to the whole brain, and/ or stereotactic radiosurgery (SRS). Studies over the past decade have demonstrated the efficacy of SRS for a limited number of brain metastases, though controversy remains regarding appropriateness, patient selection, and timing of SRS use. The uptake of SRS use in the United States during this period has not been evaluated. We evaluated national practice patterns for patients with metastatic disease receiving radiotherapy to the brain. Materials/Methods: We queried the National Cancer Data Base for patients diagnosed with metastatic non-small cell lung cancer (NSCLC), breast cancer, melanoma, and colorectal cancer from 2004 to 2014 who received upfront radiotherapy to the brain with available dose information. Patients who received documented SRS or radiation with dose per fraction 6 Gy were assigned to the SRS cohort, and all others were assigned to the CFRT cohort. Patient- and hospitallevel predictors of SRS use were analyzed with univariable chisquare tests and multivariable mixed-effects logistic regression. All statistical tests were two-sided and P < .05 was statistically significant. Results: Of 75,962 patients treated among 1,215 facilities, 12,332 (16.2%) received SRS and 63,630 (83.8%) received CFRT. The proportion of patients receiving upfront SRS increased yearly, from 9.9% of patients in 2004 to 25.6% in 2014 (P < .001). The number of facilities using SRS also increased yearly from 264 (21.7%) in 2004 to 542 (44.6%) in 2014. SRS was utilized least among breast cancer patients (12.1%) and most among melanoma patients (26.9%). On multivariable analysis, predictors of CFRT use included Black or Hispanic race/ ethnicity (OR: 1.27, 95%CI: 1.07 e 1.50), non-private insurance (OR: 1.20, 95%CI: 1.14 e 1.27), lower income (OR: 1.19, 95%CI: 1.12 e 1.26), non-academic facility (OR: 2.02, 95%CI: 1.73 e 2.37), and nonmetropolitan area (OR: 1.12, 95%CI: 1.03 e 1.21). SRS use increased disproportionally among higher-income and privately insured patients during the study period. Conclusion: This national study demonstrates a steady increase in SRS utilization for patients with brain metastases over the past decade. The