Associations between glycemic traits and colorectal cancer: a Mendelian randomization analysis

Scientists from the International Agency for Research on Cancer (IARC) and partner institutions have found that having higher circulating levels of fasting insulin increases an individual’s risk of developing colorectal cancer. The results have been published in the Journal of the National Cancer Institute.

The research team explored whether glycaemic traits that have previously been associated with higher risk of colorectal cancer, such as hyperinsulinaemia, hyperglycaemia, and type 2 diabetes, can directly promote disease development or are merely associations with no causative role.

The scientists studied genetic data from 48 214 patients with colorectal cancer and 64 159 individuals who were cancer-free. They found that higher circulating levels of fasting insulin increased risk of colorectal cancer. There was little evidence of effects of 2-hour glucose level or fasting glucose level on colorectal cancer risk. Genetic liability to type 2 diabetes and higher concentration of glycated haemoglobin (HbA1c) appeared to increase colorectal cancer risk, but other elements may have influenced these findings.

These results provide strong support for a causal effect of fasting insulin levels, but not of hyperglycaemia or type 2 diabetes, on increasing risk of colorectal cancer. The findings suggest that pharmacological or lifestyle interventions that lower circulating insulin levels may be beneficial in preventing colorectal tumorigenesis.

Murphy N, Song M, Papadimitriou N, Carreras-Torres R, Langenberg C, Martin RM, et al.
Associations between glycemic traits and colorectal cancer: a Mendelian randomization analysis
J Natl Cancer Inst, Published online 20 January 2022;
https://doi.org/10.1093/jnci/djac011

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