Meta-analysisindependent cross-checkabstract only checked I-DRY-06 standard review
Men with higher IGF-1 levels get prostate cancer somewhat more often
A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk.
Overview
Travis RC et al.. Cancer Res 2016 · PMID 26921328 · DOI 10.1158/0008-5472.CAN-15-1551
Top vs bottom fifth: OR 1.29.
Does the study support the specific claim? Yes · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
IGF and prostate cancer.
- How was the study done?
IPD meta-analysis.
- How many people, animals or samples were studied?
10,554 cases.
- What was actually found?
IGF-I associated.
- How large was the observed effect?
OR 1.29 (1.16-1.43).
- What do the results mean in everyday life?
A real but moderate link.
- What are the study's limitations?
Does not test milk.
- What does it say about Elawady's specific claim?
Supports mechanism half.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
That milk causes cancer.
Scientific in-depth review
1. Full reference
- Authors
- Travis RC et al.
- Journal
- Cancer Res
- Year
- 2016
- Identifier
- PMID 26921328 DOI 10.1158/0008-5472.CAN-15-1551
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Grants listed in PubMed: Cancer Research UK, NCI NIH HHS
2. Research question
Circulating IGFs and prostate cancer risk.
3. Study design and population
- Study design
- Meta-analysis – Individual participant data meta-analysis of 17 prospective and 2 cross-sectional studies.
- Population
Men in 19 studies
- Country
Multinational
- Period
n/a
- Sample size
Up to 10,554 cases and 13,618 controls
- Inclusion and exclusion criteria
Studies with IGF measurements.
4. Methods and endpoints
- Exposure / intervention
IGF-I, IGF-II, IGFBP-1/2/3
- Comparator
Lowest fifth
- Endpoints
Prostate cancer.
- Statistical methods
Conditional logistic regression.
5. Actual results
- Results
Prospective studies, highest vs lowest fifth: IGF-I OR 1.29 (1.16-1.43); IGFBP-1 0.81 (0.68-0.96); IGFBP-3 1.25 (1.12-1.40); after mutual adjustment only IGF-I remained associated.
- Absolute risks
not reported
- Authors' conclusion
Strong evidence that IGF-I is highly likely to be involved in prostate cancer development.
6. Strengths
- IPD pooling
- Prospective sera
7. Weaknesses
- Does not address diet
- Observational
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Strong observational design.
9. Assessment of the statistical interpretation
Moderate OR, precise.
10. Relevance to the specific claim
Supports the IGF-I-prostate cancer link (C-DRY-06, C-DRY-04).
11. Independent contrary findings
None.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Robust biomarker association.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | high |
| Directness | indirect |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Diet contribution.
15. Linked fact checks
- Dairy consumption increases prostate cancer risk (7% per 400 g/day; 34% for more than 2.5 servings/day). – Studies supporting the claim
- Milk intake raises circulating IGF-1, and higher IGF-1 increases prostate cancer risk; this is the mechanism behind the dairy-prostate cancer link ('the same hormone that makes a calf grow'). – Studies supporting the claim