Colorectal Cancer Screening in Canada: Results from the First Round of Screening for Five Provincial Programs
Bibliographic record
Abstract
BACKGROUND: Early implementation of programmatic colorectal cancer (crc) screening for average-risk individuals 50-74 years of age in Canada has used fecal occult blood tests [fts (guaiac or immunochemical)] and colonoscopy for follow-up of abnormal fts. This paper presents results of an evaluation of this crc screening. METHODS: Five Canadian provincial programs provided aggregated data for individuals with a first-round ft processed between January 1, 2009, and December 31, 2011. RESULTS: The 104,750 people who successfully completed a first round of screening represented 16.1% of those who had access to the programs between January 1, 2009, and December 31, 2011 (mean age: 61.2 years; men: 61.4 years; women: 61.1 years). Of those participants, 4661 had an abnormal ft (4.4%). Uptake of colonoscopy within 180 days after an abnormal ft was 80.5%, ranging from 67.8% to 89.5% by program. The positive predictive value (ppv) for adenoma was 35.9% for guaiac ft and 50.6% for immunochemical ft. Adenoma and crc detection rates were, respectively, 16.9 and 1.8 per 1000 screened. Of invasive crcs detected, 64.6% were stage i or ii. CONCLUSIONS: Considering the variation in characteristics and stage of implementation of each provincial program, the collaboration of the provinces leading to this report on the early performance of crc screening in Canada is a major milestone. Targets are met or nearly met for significant indicators such as ppv for adenoma and cancer detection rate. Participation is expected to increase as programs are fully implemented in the provinces. Additional effort may be needed to improve timely access to follow-up colonoscopy.
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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 | 0.002 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.006 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.001 |
| 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".