RADT-11. PROTON BEAM THERAPY (PBT) FOR CENTRAL NERVOUS SYSTEM (CNS) TUMOURS IN CHILDREN: A CANADIAN PEDIATRIC BRAIN TUMOUR CONSORTIUM STUDY
Bibliographic record
Abstract
Abstract BACKGROUND Radiotherapy is important for treating pediatric CNS tumours. The main modalities include photon therapy and PBT. PBT offers potential advantages over photon therapy in children since its precise dose control can limit long-term side effects. However, Canadian patients needing PBT are referred to the United States (US) because PBT is unavailable in Canada. We aimed to describe PBT use and outcomes over time for Canadian pediatric patients with CNS tumours. METHODS Patient demographics, treatment characteristics, and outcomes were extracted from medical records of patients from 10/13 Canadian provinces/territories. Patients diagnosed with a CNS tumour at ≤20 years old between 2001-2021 who received curative-intent PBT were included. PBT plans were compared using Fisher’s exact or Kruskal-Wallis rank sum tests. Overall survival (OS) was estimated using the Kaplan-Meier method. RESULTS Of 195 patients (59.0% male) included in the study, majority were from Alberta (28.7%), Quebec (26.7%), British Columbia (22.6%), and Ontario (20.5%). Median age at diagnosis was 8.0 years. Most tumours (77.9%) were non-metastatic. Medulloblastoma was the most common diagnosis (30.8%). Provinces/territories referred patients to proton centres in the same geographical regions, except Alberta (74.5% referred to Florida). Referral numbers have increased ~180%/year since 2011. Median time from diagnosis to PBT was 126 days [11-5236] for all patients, and 36 days [21-1313] for medulloblastoma. Radiation doses, irradiation site, therapy duration, and time to treatment were not different (p≥0.2) across all PBT facilities for medulloblastoma. 5-year OS were 86.8% and 73.0% for the PBT study population and the Cancer in Young People-Canada reference population, respectively, in those aged <15 years. CONCLUSIONS Given the unavailability of PBT in Canada, pediatric CNS tumour patients were referred to US PBT facilities close in proximity. Further studies are needed to better understand provincial referral patterns and barriers to equitable PBT access across Canada.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".