Re: Canadian National Breast Screening Study-2: 13-Year Results of a Randomized Trial in Women Aged 50-59 Years
Bibliographic record
Abstract
Miller et al. (1) report on the most recent results of a randomized trial of breast screening in Canada. At 16 years after randomization, there were 107 deaths observed among women randomly assigned to receive annual mammography plus physical examination and 105 deaths among a similar number of women randomly assigned to receive an annual physical examination alone. The authors interpret this to mean that that the two methods of screening were equivalent—i.e., that annual physical examination by a trained professional is a viable alternative to annual mammography and should be available to women 50 years old or older. This message has also been highlighted by several media reports covering the publication of the trial results. If this were a trial of mammography alone versus physical examination alone, this conclusion would be rational. However, if mammography and physical examination were equivalent (but not identical), I would expect the combination of the two to outperform either modality alone. In fact, the combination of mammography plus physical examination outperformed physical examination alone by every measure—except death. The tumors in the mammography arm were smaller, on average, than those detected in the physical examination arm and were more likely to be lymph node negative. Miller et al. present data showing that physical examination advanced the date of diagnosis by 1.5 years but that adding mammography advanced it further by 2.1 years. Surely, if physical examination were beneficial, then mammography must be more so. If early detection enhances the prospect of cure, a lead time of 3.6 years must be preferable to a lead time of 1.5 years. But this was not found to be the case. The rational interpretation of this dataset is not that the two screening methods were equivalent, but that neither was effective. I believe that researchers should now devote their attention to understanding why this is the case and should pay greater attention to advancing primary prevention.
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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 | 0.008 | 0.034 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.006 | 0.002 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.011 | 0.007 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".