Serum insulin-like growth factor (IGF) and IGF-binding protein levels and risk of lung cancer: a case-control study nested in the beta-Carotene and Retinol Efficacy Trial Cohort.
Bibliographic record
Abstract
Recent prospective studies have suggested that insulin-like growth factor (IGF)-I levels are related to risk of some epithelial cancers. We previously reported in a case-control study a significant association between IGF-I level and lung cancer risk, with a 2-fold increased risk in the highest quartile. We now report the results of a lung cancer case-control study nested in the placebo arm of the beta-Carotene and Retinol Efficacy Trial in heavy smokers. We identified 159 cases for whom sera had been collected at least 3 years before diagnosis and for whom 2 suitable controls/case (final number, 297) could be matched from the same study arm on age (within 5-year intervals), sex, ethnicity, year of enrollment into the beta-Carotene and Retinol Efficacy Trial, year of blood draw, and exposure category (smoking or asbestos). The cases were significantly heavier smokers than the controls (mean pack-years, 58.7 and 45.9, respectively; P < 0.001). An inverse relationship between IGF-I level and age was evident only for former smokers, and not for those who were current smokers at the time of blood draw. Both IGF-I and IGF-binding protein (IGFBP)-3 levels were higher in cases than in controls, but none of the differences achieved statistical significance. The odds ratios for IGF-I were around unity, except for subsets of heaviest smokers and those who had quit smoking for the longest period of time, in whom there were elevated risks in the second to fourth quartiles of IGF-I relative to the first quartile (odds ratios, 2.21-2.91), although again, none achieved statistical significance. For younger subjects, IGF-I was inversely associated with lung cancer risk in the models that also controlled for IGFBP-3. Elevated risks for lung cancer were noted in the highest quartile of IGFBP-3 level, and these tended to be higher in current smokers and more recent quitters. These results do not support the conclusions of our prior case-control study. It is possible that current smoking or recent cessation may exert a suppressive effect on IGF-I levels (notably in younger subjects with higher baseline levels) that may obscure a relatively modest association between IGF-I level and lung cancer risk. On the other hand, risks associated with elevated IGFBP-3 level tended to be higher in current smokers and more recent quitters. This trend toward a positive association with IGFBP-3 level is unexpected and requires further investigation. Finally, from these data, we cannot exclude the possibility that risk of lung cancer in nonsmokers may be related to IGF-I levels.
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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) | 0.002 | 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".