Neoadjuvant Chemotherapy Without Radiation for Locally Advanced Rectal Cancer: A Meta-analysis of Surgical Outcomes After Total Mesorectal Excision
Bibliographic record
Abstract
BACKGROUND: Neoadjuvant chemotherapy alone (with radiation omission) for locally advanced rectal cancer has been evaluated in several randomized controlled trials. Although oncologic outcomes have been well described, the impact of this treatment strategy on surgical outcomes is unknown. OBJECTIVE: To evaluate how important surgical outcomes were reported in previous trials comparing neoadjuvant chemotherapy to chemoradiation therapy for locally advanced rectal cancer and to perform a meta-analysis of available data. DATA SOURCES: A systematic review was conducted using MEDLINE, Embase, and the Cochrane Library Databases. STUDY SELECTION: All published randomized controlled trials that compared neoadjuvant chemotherapy to chemoradiation for MRI-staged rectal adenocarcinoma. INTERVENTIONS: Neoadjuvant chemotherapy alone (with radiation omission). MAIN OUTCOME MEASURES: Postoperative surgical outcomes, including anastomotic leak, diverting ostomy use, ostomy nonreversal, 30-day postoperative morbidity, and postoperative bowel function. RESULTS: Four randomized controlled trials met eligibility criteria and were included for data analysis. Oncologic outcomes demonstrated that neoadjuvant chemotherapy was equivalent or noninferior to chemoradiation therapy. Anastomotic leak and use of diverting ostomy were reported in 3 of the 4 trials, whereas 30-day postoperative morbidity and ostomy nonreversal were reported in only 2 trials. Bowel function was measured in 3 trials but was measured and reported differently in each trial. On meta-analysis, neoadjuvant chemotherapy was associated with a significant reduction in anastomotic leak (relative risk [RR] 0.54; 95% CI, 0.35-0.81), use of diverting ostomy (RR 0.79; 95% CI, 0.70-0.88), and ostomy nonreversal (RR 0.37; 95% CI, 0.15-0.93). There was no association between neoadjuvant chemotherapy and 30-day postoperative morbidity (RR 0.88; 95% CI, 0.53-1.45). LIMITATIONS: A small number of included trials with heterogeneity in outcome definitions was the limitation. CONCLUSIONS: Important surgical outcomes were not reported in trials comparing neoadjuvant chemotherapy alone to chemoradiation therapy for locally advanced rectal cancer. Based on the limited data available, chemotherapy alone was associated with reduced risk of anastomotic leak, diverting ostomy use, and ostomy nonreversal. See Video Abstract .
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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 | 0.014 | 0.028 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.014 | 0.054 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".