Predicting acute small-bowel toxicity in patients with rectal cancer treated with neoadjuvant chemoradiation: A comparison of peritoneal space versus small-bowel loop contouring techniques.
Bibliographic record
Abstract
673 Background: In lieu of contouring individual small bowel loops, the peritoneal space (PS) has been suggested as a possible surrogate volume for predicting small bowel toxicity. A dose-volume relationship for the PS has not been firmly established. The aim of this study was to determine whether contours of the PS better predict significant acute small bowel toxicity in neoadjuvant rectal cancer patients when compared with contours of individual small bowel loops. Methods: A standardized contouring method was developed for the PS and retrospectively applied to the radiation treatment plans of sixty-seven patients treated with neoadjuvant chemoradiotherapy for rectal cancer. All patients had locally advanced disease, no evidence of metastases, and received concurrent radiation and infusional 5-Fluorourocil chemotherapy. Dose-volume histogram (DVH) data was extracted and analyzed against patient toxicity. Receiver operating characteristic analysis and logistic regression was carried out for both contouring methods. Results: Grade ≥ 3 small bowel toxicity occurred in 16% (11/67) of patients. Volumes of the contoured small bowel loops correlated with grade ≥ 3 toxicity at each 5 Gray (Gy) dose level from 5 to 45 Gy, with the greatest area under the curve (AUC) measuring .964 (p=.000) associated with the volume receiving at least 25 Gy (V25). Volumes of the contoured PS predicted toxicity from 5 to 40 Gy, with the greatest AUC also at the V25 and measuring .896 (p=.000). Logistic regression analysis demonstrated a less than 15% risk of acute grade ≥ 3 toxicity was associated with a V25 of 215 cc for the small bowel and 710 cc for the PS. Conclusions: DVH analysis of peritoneal space volumes predicts grade ≥ 3 small bowel toxicity in neoadjuvant rectal cancer patients, suggesting the peritoneal space is a reasonable surrogate for contouring individual small bowel loops. However, contouring individual small bowel loops is a more sensitive method for predicting toxicity at each dose increment. For both contouring methods, the greatest sensitivity for predicting toxicity was associated with the volume receiving at least 25 Gy (V25).
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | high |
| gpt | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | medium |
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) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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, unvalidatedLabeled directly by 2 models reading the full record.
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".