Screening with prostate specific antigen and metastatic prostate cancer risk: A population-based case-control study
Bibliographic record
Abstract
4651 Background: Screening of asymptomatic men with the prostate specific antigen (PSA) is a highly controversial issue. There is little evidence to date that such screening is effective in reducing mortality from prostate cancer. We conducted a population-based case-control study to determine if screening with PSA reduces the risk of metastatic prostate cancer. Methods: The study was carried out in Metropolitan Toronto and five surrounding counties in Ontario, Canada. Cases were men diagnosed with metastatic prostate cancer between August 1, 1999 and May 31, 2002. Controls were randomly sampled from the source population and matched to cases for age, area of residence, and observation time. Medical records and a self-administered questionnaire were used to collect the data. We obtained information on PSA testing, digital rectal exams, symptoms, comorbidity, use of health services, as well as known and suspected risk factors for prostate cancer. Analyses were performed on 236 cases and 462 controls. Results: After adjustment for observation time, the frequency of screening among asymptomatic men was 24.6% in the cases and 33.1% in the controls (odds ratio 0.66, 95% confidence interval 0.47 to 0.92). Self-reported screening was also significantly less frequent among the cases (odds ratio 0.48, 0.34 to 0.67). No significant confounding was found in multiple logistic regression analyses. Secondary analyses including symptomatic and asymptomatic men showed that the cases generally had fewer symptoms and fewer PSA tests than the controls, except for the last year before the diagnosis of prostate cancer. In symptomatic men, the association between PSA testing and metastatic prostate cancer was not significant. Conclusions: The results suggest that screening of asymptomatic men with PSA may substantially reduce the risk of metastatic prostate cancer. Further research is needed to confirm these results in a randomized trial and to assess the economic and quality of life aspects of PSA screening. No significant financial relationships to disclose.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".