A FIRST REPORT ON OUTCOMES OF STEREOTACTIC BODY RADIOTHERAPY FOR POSTERIOR ELEMENT ONLY SPINAL METASTASES AND VALIDATION OF RECOMMENDED CLINICAL TARGET VOLUME DELINEATION PRACTICE
Bibliographic record
Abstract
Abstract Spine stereotactic body radiotherapy (SBRT) improves local control and pain response compared to conventional external beam radiotherapy. Consensus stipulates MRI-based delineation of the clinical target volume (CTV) and is based on spine segment sector involvement. The applicability to metastases limited to the posterior elements remains to be validated. We aimed to determine the patterns of failure and safety of treating posterior element metastases when the vertebral body (VB) was intentionally excluded from the CTV. METHODS AND MATERIALS: A retrospective review of a prospectively maintained database of 605 patients and 1412 spine segments treated with spine SBRT was performed. Only treated segments involving the posterior elements alone were included. The primary outcome was local failure and secondary outcomes included patterns of failure, toxicities. RESULTS: 24/605 patients and 31/1412 segments were treated to the posterior elements only. Local failure occurred in 11/31 segments. The cumulative rate of local recurrence was 9.7% at 12 months and 30.8% at 24 months. Amongst local failures, the most common histologies were renal cell carcinoma (36.4%) and non-small cell lung cancer (36.4%) and 73% had baseline paraspinal disease extension. 6/11 (54.5%) failed exclusively within treated CTV sectors and 5/11 (45.5%) with both treated and adjacent untreated sectors. 4/5 cases had recurrent disease extending into the VB, but no failure was observed exclusively within the VB. CONCLUSIONS: Posterior element alone metastases are rare. Our analyses support SBRT consensus contouring guidelines such that the VB can be excluded from CTV in spinal metastases confined to the posterior elements.
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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 | 0.003 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".