Association of tamoxifen use and reduced risk of contralateral breast cancer for BRCA1 and BRCA2 mutation carriers
Bibliographic record
Abstract
Background: The efficacy of tamoxifen as a breast cancer (BC) prevention strategy for BRCA1 and BRCA2 mutation carriers is uncertain. Patients and methods: Female BRCA1 and BRCA2 mutation carriers, with a personal history of BC since 1970, enrolled in any of the BC family studies, kConFab (Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer), IBCCS (International BRCA1 and BRCA2 Carrier Cohort Study), or BCFR (Breast Cancer Family Registry) were eligible. Those with bilateral disease at first BC diagnosis, tamoxifen use prior to their first BC diagnosis, or another invasive cancer with were excluded. Data were self-reported at entry into the cohort and at follow-up. Hazard ratios (HRs) for development of contralateral BC associated with tamoxifen use after first BC diagnosis were estimated using Cox proportional hazards, modeling time from diagnosis of first primary BC, adjusting for year of birth (continuous), age at diagnosis (continuous), country and bilateral oophorectomy (yes/no, time-varying). Data were censored at contralateral mastectomy, death or loss to follow-up. Results: Of 1642 BRCA1 and 919 BRCA2 mutation carriers, 374 (23%) and 444 (48%), respectively, took tamoxifen after their first BC diagnosis. During 21,344 person-years of follow-up, 596 contralateral BCs were observed. Overall, the adjusted HR estimates were 0.31 (95% CI: 0.22-0.45) and 0.24 (95% CI 0.16-0.35) for BRCA1 and BRCA2 mutation carriers, respectively. After left-truncating the analysis at time of recruitment, the adjusted HR estimates were 0.52 (95% CI: 0.26-1.04) and 0.39 (95% CI: 0.17-0.89) from studying 629 BRCA1 and 412 BRCA2 mutation carriers, respectively, with 4,869 person-years of follow-up. Conclusions: Although biased estimates due to non-random use of tamoxifen cannot be excluded, these results are consistent with tamoxifen reducing BC risk for both BRCA1 and BRCA2 mutation carriers.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".