Rectal Cancer Incidence is Low Following Rectal Diversion or Subtotal Colectomy for IBD: Results of a Population-based Study
Bibliographic record
Abstract
BACKGROUND AND AIMS: Following subtotal colectomy or diversion for medically refractory inflammatory bowel disease [IBD], completion proctectomy has been recommended to reduce the risk of rectal cancer. However, this recommendation is based on low-quality evidence. Our objectives were to estimate the cumulative incidence of rectal cancer and evaluate if surveillance endoscopy reduces the risk of rectal cancer. METHODS: We performed a population-based retrospective cohort study in Ontario, Canada, of all patients undergoing either subtotal colectomy or diversion for medically refractory IBD over 1991-2015. We excluded patients with a previous history of colorectal cancer or previous rectal resection, and those with <1 year of observation. We calculated the rate of incident rectal cancer using a competing risks model, and evaluated the effect of surveillance endoscopy on the rate of rectal cancer. RESULTS: In all, 3700 patients were included with a median follow-up of 4.3 years. Of this cohort, 47% underwent rectal resection or restoration of gastrointestinal [GI] continuity during the observation period; 40 patients were diagnosed with rectal cancer, with a cumulative incidence of rectal cancer of 0.81% (95% confidence interval [CI] 0.53%, 1.20%) and 1.86% [95% CI 1.29%, 2.61%] at 10 and 20 years, respectively. Surveillance endoscopy was associated with a lower rate of rectal cancer (subhazard ratio [sHR] 0.37, 95% CI 0.16, 0.82, p = 0.014]. CONCLUSIONS: Among patients with a retained rectum following surgery for IBD, the risk of rectal cancer is low and appears to be lower when surveillance endoscopy is performed. Expectant management with surveillance endoscopy may be a reasonable alternative to completion proctectomy in selected patients.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".