Impact of changing from annual to biennial mammographic screening on breast cancer outcomes in women aged 50–79 in British Columbia
Bibliographic record
Abstract
OBJECTIVES: The objective of this study was to compare breast cancer outcomes among women subject to different policies on mammography screening frequency. SETTING: Data were obtained for women participating in the Screening Mammography Programme of British Columbia (SMPBC) for 1988--2005. The SMPBC changed its policy for women aged 50-79 years from annual to biennial mammography in 1997, but retained an annual recommendation for women aged 40-49 years. METHODS: Breast cancer outcomes were compared for women participating in the programme before and after 1997 for two groups: ages 40-49 and 50-79 years. RESULTS: There were data on 658,151 women. Comparing pre-1997 and post-1997, the median interscreen interval increased by 11.1 months in women 50-79 but by only 0.3 months in women aged 40-49. Excluding those detected at initial screen, 6291 breast cancers were identified. Comparing pre-1997 and post-1997: the relative rates (RR) of screen detected cancer increased in women aged 40-49 (RR = 1.32) and the rate of invasive cancers > or =20 mm at diagnosis decreased (RR = 0.83); the rate of cancers with axillary node involvement increased in women aged 50-79 (RR = 1.23). Cancer survival improved after 1997 for women diagnosed at ages 40-49 (hazard ratio = 0.62), but was unchanged for women aged 50-79. Breast cancer mortality rates did not change between the periods in either age group. CONCLUSION: The proximal cancer outcomes considered (staging and survival) improved in women aged 40-49 but this was offset in women aged 50-79 associated with the change in screen frequency. These changes did not result in alterations in breast cancer mortality rates in either age group.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".