Patterns of proton therapy use in pediatric cancer management in 2016: An international survey.

PURPOSE: To facilitate the initiation of observational studies on late effects of proton therapy in pediatric patients, we report on current patterns of proton therapy use worldwide in patients aged less than 22 years. MATERIALS & METHODS: Fifty-four proton centers treating pediatric patients in 2016 in 11 countries were invited to respond to a survey about the number of patients treated during that year by age group, intent of treatment, delivery technique and tumor types. RESULTS: Among the 40 participating centers (participation rate: 74%), a total of 1,860 patients were treated in 2016 (North America: 1205, Europe: 432, Asia: 223). The numbers of patients per center ranged from 1 to 206 (median: 29). Twenty-four percent of the patients were <5 years of age, and 50% <10 years. More than 30 pediatric tumor types were identified, mainly treated with curative intent: 48% were CNS, 25% extra-cranial sarcomas, 7% neuroblastoma, and 5% hematopoietic tumors. About half of the patients were treated with pencil beam scanning. Treatment patterns were broadly similar across the three continents. CONCLUSION: To our knowledge, this survey provides the first worldwide assessment of proton therapy use for pediatric cancer management. Since previous estimates in the United States and Europe, CNS tumors remain the cancer types most commonly treated with protons in 2016. However, the proportion of extra-cranial tumors is growing worldwide. The typically low numbers of patients treated in each center indicate the need for international research collaborations to assess long-term outcomes of proton therapy in pediatric patients.

Commissioning an in-room mobile CT for adaptive proton therapy with a compact proton system.

PURPOSE: To describe the commissioning of AIRO mobile CT system (AIRO) for adaptive proton therapy on a compact double scattering proton therapy system. METHODS: A Gammex phantom was scanned with varying plug patterns, table heights, and mAs on a CT simulator (CT Sim) and on the AIRO. AIRO-specific CT-stopping power ratio (SPR) curves were created with a commonly used stoichiometric method using the Gammex phantom. A RANDO anthropomorphic thorax, pelvis, and head phantom, and a CIRS thorax and head phantom were scanned on the CT Sim and AIRO. Clinically realistic treatment plans and nonclinical plans were generated on the CT Sim images and subsequently copied onto the AIRO CT scans for dose recalculation and comparison for various AIRO SPR curves. Gamma analysis was used to evaluate dosimetric deviation between both plans. RESULTS: AIRO CT values skewed toward solid water when plugs were scanned surrounded by other plugs in phantom. Low-density materials demonstrated largest differences. Dose calculated on AIRO CT scans with stoichiometric-based SPR curves produced over-ranged proton beams when large volumes of low-density material were in the path of the beam. To create equivalent dose distributions on both data sets, the AIRO SPR curve's low-density data points were iteratively adjusted to yield better proton beam range agreement based on isodose lines. Comparison of the stoichiometric-based AIRO SPR curve and the "dose-adjusted" SPR curve showed slight improvement on gamma analysis between the treatment plan and the AIRO plan for single-field plans at the 1%, 1 mm level, but did not affect clinical plans indicating that HU number differences between the CT Sim and AIRO did not affect dose calculations for robust clinical beam arrangements. CONCLUSION: Based on this study, we believe the AIRO can be used offline for adaptive proton therapy on a compact double scattering proton therapy system.

The Mobius AIRO mobile CT for image-guided proton therapy: Characterization & commissioning.

PURPOSE: The purpose of this study was to characterize the Mobius AIRO Mobile CT System for localization and image-guided proton therapy. This is the first known application of the AIRO for proton therapy. METHODS: Five CT images of a Catphan® 504 phantom were acquired on the AIRO Mobile CT System, Varian EDGE radiosurgery system cone beam CT (CBCT), Philips Brilliance Big Bore 16 slice CT simulator, and Siemens SOMATOM Definition AS 20 slice CT simulator. DoseLAB software v.6.6 was utilized for image quality analysis. Modulation transfer function, scaling discrepancy, geometric distortion, spatial resolution, overall uniformity, minimum uniformity, contrast, high CNR, and maximum HU deviation were acquired. Low CNR was acquired manually using the CTP515 module. Localization accuracy and CT Dose Index were measured and compared to reported values on each imaging device. For treatment delivery systems (Edge and Mevion), the localization accuracy of the 3D imaging systems were compared to 2D imaging systems on each system. RESULTS: The AIRO spatial resolution was 0.21 lp mm-1 compared with 0.40 lp mm-1 for the Philips CT Simulator, 0.37 lp mm-1 for the Edge CBCT, and 0.35 lp mm-1 for the Siemens CT Simulator. AIRO/Siemens and AIRO/Philips differences exceeded 100% for scaling discrepancy (191.2% and 145.8%). The AIRO exhibited higher dose (>27 mGy) than the Philips CT Simulator. Localization accuracy (based on the MIMI phantom) was 0.6° and 0.5 mm. Localization accuracy (based on Stereophan) demonstrated maximum AIRO-kV/kV shift differences of 0.1 mm in the x-direction, 0.1 mm in the y-direction, and 0.2 mm in the z-direction. CONCLUSIONS: The localization accuracy of AIRO was determined to be within 0.6° and 0.5 mm despite its slightly lower image quality overall compared to other CT imaging systems at our institution. Based on our study, the Mobile AIRO CT system can be utilized accurately and reliably for image-guided proton therapy.

Primary treatments for clinically localised prostate cancer: a comprehensive lifetime cost-utility analysis.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Multiple treatment alternatives exist for localised prostate cancer, with few high-quality studies directly comparing their comparative effectiveness and costs. The present study is the most comprehensive cost-effectiveness analysis to date for localised prostate cancer, conducted with a lifetime horizon and accounting for survival, health-related quality-of-life, and cost impact of secondary treatments and other downstream events, as well as primary treatment choices. The analysis found minor differences, generally slightly favouring surgical methods, in quality-adjusted life years across treatment options. However, radiation therapy (RT) was consistently more expensive than surgery, and some alternatives, e.g. intensity-modulated RT for low-risk disease, were dominated - that is, both more expensive and less effective than competing alternatives. OBJECTIVE: To characterise the costs and outcomes associated with radical prostatectomy (open, laparoscopic, or robot-assisted) and radiation therapy (RT: dose-escalated three-dimensional conformal RT, intensity-modulated RT, brachytherapy, or combination), using a comprehensive, lifetime decision analytical model. PATIENTS AND METHODS: A Markov model was constructed to follow hypothetical men with low-, intermediate-, and high-risk prostate cancer over their lifetimes after primary treatment; probabilities of outcomes were based on an exhaustive literature search yielding 232 unique publications. In each Markov cycle, patients could have remission, recurrence, salvage treatment, metastasis, death from prostate cancer, and death from other causes. Utilities for each health state were determined, and disutilities were applied for complications and toxicities of treatment. Costs were determined from the USA payer perspective, with incorporation of patient costs in a sensitivity analysis. RESULTS: Differences across treatments in quality-adjusted life years across methods were modest, ranging from 10.3 to 11.3 for low-risk patients, 9.6-10.5 for intermediate-risk patients and 7.8-9.3 for high-risk patients. There were no statistically significant differences among surgical methods, which tended to be more effective than RT methods, with the exception of combined external beam + brachytherapy for high-risk disease. RT methods were consistently more expensive than surgical methods; costs ranged from $19 901 (robot-assisted prostatectomy for low-risk disease) to $50 276 (combined RT for high-risk disease). These findings were robust to an extensive set of sensitivity analyses. CONCLUSIONS: Our analysis found small differences in outcomes and substantial differences in payer and patient costs across treatment alternatives. These findings may inform future policy discussions about strategies to improve efficiency of treatment selection for localised prostate cancer.

Durable response of a radiation-induced, high-grade cerebellar glioma to temozolomide.

BACKGROUND: Radiation-induced high-grade gliomas are a rare but serious late complication of radiotherapy. We report a patient with radiation-induced cerebellar high-grade glioma who had a durable response to temozolomide. PATIENTS AND METHODS: Case report of a 77-year-old woman with a radiation-induced, high-grade cerebellar glioma that responded durably to temozolomide. RESULTS: Our patient developed a cerebellar high-grade glioma 9 years after treatment for a stage IV (T4N0M0) supraglottic laryngeal squamous cell carcinoma with cisplatinum and fluorouracil chemotherapy, and subsequently focal head and neck radiotherapy. Patient was treated with radiation and concurrent temozolomide (only partially due to toxicity) and was stable for 1 year without further adjuvant treatment. Subsequently the tumor recurred and the patient had a dramatic and durable response to standard 5 day dosing of adjuvant temozolomide. CONCLUSION: High-grade gliomas are a late complication of radiation to the central nervous system and may respond to chemotherapy.