30 GY IN 4 STEREOTACTIC BODY RADIOTHERAPY (SBRT) FRACTIONS FOR COMPLEX SPINAL METASTASES: MATURE OUTCOMES SUPPORTING THIS NOVEL REGIMEN
Bibliographic record
Abstract
Abstract We designed a 30 Gy in 4 fractions stereotactic body radiotherapy (SBRT) protocol, as an alternative option to our standard 2-fraction approach, for primarily large volume, multilevel, or previously radiated spinal metastases. We report imaging-based outcomes of this novel fractionation scheme. MATERIALS AND METHODS: Retrospective analysis of all patients who underwent 30 Gy/4 fractions from 2010-2021 identified from an institutional database. Primary outcomes were magnetic resonance-based vertebral compression fracture (VCF) and local failure (LF). RESULTS: We reviewed 245 treated segments in 116 patients. The median number of consecutive segments within the treatment volume was 2 (range, 1-6) and clinical target volume (CTV) was 126.2 cc (range, 10.4-863.5). Fifty-four percent had received at least one prior course of radiotherapy. The cumulative incidence of LF was 10.7% (95% CI 7.1-15.2) at 1 year and 16% (95% CI 11.5-21.2) at 2 years. The cumulative incidence of VCF was 7.3% (95% CI 4.4-11.2) at 1 and 11.2% (95% CI 7.5-15.8) at 2 years. On multivariable analysis, age ≥68 years (p=0.038), CTV volume ≥72 cc (p=0.021), and no prior surgery (p=0.021) predicted for VCF. The risk of VCF for CTV volumes <72 cc/≥72 cc was 1.8%/14.6% at 2 years. No case of radiation-induced myelopathy was observed. CONCLUSION: 30 Gy in 4 fractions was safe and efficacious despite a population at increased risk of toxicity. The lower risk of VCF in previously stabilized segments highlights the potential for a multi-modal treatment approach for complex metastases, especially for those with CTV volume ≥72 cc.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 teacher head, 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".