Hyper-insulinaemia and cancer, meta-analyses of epidemiological studies.
Level 3 - non-randomized controlled study
Meta-analysis of non-randomized observational/cohort studies
PubMed 18465360 · doi:10.1080/13813450801954451
What was done
Authors searched PubMed for epidemiological studies (primarily prospective cohort studies using baseline or pre-diagnostic blood samples) investigating the relationship between markers of hyperinsulinemia and glycemia (insulin, C-peptide, glucose, HbA1c) and the risk of colon, rectum, pancreas, breast, and endometrial cancers. Multivariate-adjusted relative risks (RRs) and 95% confidence intervals were pooled in meta-analyses.
What was found
The meta-analyses identified excess risks of colorectal and pancreatic cancers associated with higher levels of circulating C-peptide/insulin and glycemic markers. For endometrial cancer (based on four studies), significant heterogeneity was observed, resulting in a summary RR compatible with no association. For breast cancer, while overall risk was higher in upper categories of C-peptide/insulin, this excess was driven entirely by retrospective studies. Specific numerical summary effect estimates and confidence intervals were not reported in the abstract.
Why it matters
It provides pooled epidemiological evidence that pre-diagnostic hyperinsulinemia and elevated glucose levels are linked to colorectal and pancreatic cancer development, helping clarify the metabolic mechanisms underlying obesity-related cancer risk.
Limits
The abstract reports no numerical risk estimates or total participant/study counts. The findings rely largely on single-point baseline blood measurements collected years before cancer diagnosis. For breast cancer, the association was limited to retrospective designs, introducing potential recall or reverse-causality biases, and significant heterogeneity was present across endometrial cancer studies.
Cited by
- supports Insulin resistance is an underlying driver of common cancers, including breast, pancreatic, ovarian, and colon cancer.