Levonorgestrel intrauterine system and breast cancer risk: An updated systematic review and meta-analysis of observational studies
Bibliographic record
Abstract
Objectives: We conducted an updated meta-analysis (larger sample capacity and including Asian data) to explore whether LNG-IUS can increase the risk of BC. Study design: We performed a thorough review of peer-reviewed publications from January 2005 through November 2022 using combinations of search terms for BC risk and LNG-IUS in the PubMed, Cochrane, Embase, Science Direct, and Web of Science databases. Studies reporting BC risk estimates among users of LNG-IUS were included according to the PRISMA criteria. Two authors independently evaluated all studies identified from the databases using Endnote software, and a third author resolved disagreements. The quality of evidence was evaluated using the Newcastle‒Ottawa Scale (NOS). A funnel plot was generated to assess publication bias. Results: We identified 3029 studies; 12 studies were included in our systematic review, and 6 studies involving 261,221 women were included in our meta-analysis. Two subgroup analyses were performed for different study designs. A total of 190,475 women were included in the meta-analysis of cohort studies, and the results were RR = 0.80 (95% CI 0.57-1.11, Z = 1.33, P = 0.18 > 0.05). The meta-analysis of the case‒control studies included 70,746 women, and the results were OR = 1.38 (95% CI 0.98-1.94, Z = 1.85, P = 0.06 > 0.05). Conclusions: Evidence of an increased risk of BC was not observed among LNG-IUS users. Implications: There are inconsistencies in existing studies that prevent us from confirming whether LNG-IUS can increase the risk of BC. Our updated meta-analysis preliminarily suggested that LNG-IUS did not increase the risk of BC, providing evidence for more clinically safe use and thus providing a better choice for contraception.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".